: High Oil Consumption, Pulled Headbolts, Blown Head Gaskets, Bars Leak, Unstable Temps



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dkozloski
05-04-05, 11:04 AM
In the absence of any failure rate data to the contrary I am forced to conclude that the head gasket failure rate is substantial. The fact that changes have been made by the factory engineers indicates to me pretty strongly that Cadillac knows it and has reacted. I would also speculate that the bean counters have ruled that it is good enough as it is. Because they have the veto vote it is as good as it is going to get. How this compares to other machines is an unknown. The big complicating factor that turns the whole thing into a PITA is the requirement to Timesert. If it weren't for this factor the whole problem would be flying down below the radar with all the other makes with similar head gasket failures.

Maxoom
05-04-05, 11:26 AM
"The point I am making is that I am not surprised that cars with an overheating history that includes losing coolant, deteriorate to blown head gaskets on a regular basis." -dkozloski

Yep, that's true in my little world as well. Anytime an outboard gets hot enough to set off the overheat warning (temp way above normal), the heads will warp. It's usually not enough to cause an immediate failure, but the heads will be warped nonetheless. The service manual says to retorque headbolts after an overheat, but I say if it's run much or many times at the elevated temp, the heads need to come off to be checked and trued up.

Is there any correlation between N* headgasket failure and overheating (activation of the "limp home" mode)? I would expect to find a greater failure rate among engines that have been overheated.

dkozloski
05-04-05, 11:46 AM
Bbob has made reference to neoprene being used as part of the gasket sandwich for the supercharged North*. A quick check of the CRC Applied Science Handbook shows that the upper temperature service limit for neoprene is 100 Deg C. Maybe this is going to get really interesting. Hot rodders use solid or gas filled copper O-rings laid into a groove in the block or head. Maybe there is something to be learned here.

dkozloski
05-04-05, 12:07 PM
Bbob also mentioned needing a slick surface on the block and heads to implement the printed neoprene gasket. My experience is that unless the surface has some "tooth" the gasket squirts out like squeezing a pumpkin seed between your fingers. To paraphrase ***on of "Oliver Twist", "I think they better think it through again".

dkozloski
05-04-05, 01:13 PM
My solution to several problems of this type was to carefully mask the part to prevent contamination and blast the surface with fine glass beads. This treated the surface with a jillion non-continuous depressions that acted to grip the gasket and hold it in place yet provided no scratches, tool marks or grooves for a leakage path. The downsides are the lost time and the possibility of contaminating the part with the beads.

gtm2u
05-04-05, 03:29 PM
In the absence of any failure rate data to the contrary I am forced to conclude that the head gasket failure rate is substantial. The fact that changes have been made by the factory engineers indicates to me pretty strongly that Cadillac knows it and has reacted. I would also speculate that the bean counters have ruled that it is good enough as it is. Because they have the veto vote it is as good as it is going to get. How this compares to other machines is an unknown. The big complicating factor that turns the whole thing into a PITA is the requirement to Timesert. If it weren't for this factor the whole problem would be flying down below the radar with all the other makes with similar head gasket failures.

dk: Short of contacting Felpro who it would seem may be the only gasket maker for I've done a reasonable search and their's is the only one that keeps coming up I don't know how we as a consumer can determine the failure incidence rate. While it is easy to say every mfg. has their share of failures this is inordinate, short of contacting Rand corp who may have studies of how to extract trends on the Internet and the factory, the gasket maker would be about the only other source. Depart of Motor Vehicles could have some useful info showing a trend of cars getting sold at x miles or being scrapped in comparison to others.

Yes, the Timesert business is probably the red flag along with the expense incurred requiring unit removal to make repairs. The fact that other makers have successfully built aluminum engines where this problem does not exist suggests that their are other factors involved contributing or directly causal. Bolt diameter, thread pitch, and stretch was/is an issue which in many makers have been overcome by using studs. Yet another consideration is the the aluminum alloy used and what processes were used to maintain it's stability or if a process was omitted which would have prevented these failures. I've suggested seasoning was one option and heat treating as another.

I think it would be worthwhile knowing a better breakdown on failures such as the sales person who racks up 100,000 miles a year vs the person who only drives 14,000. My point here is complete heat cycles where the engine cools overnight and then is driven to stabilized operating temps and then parked. Maintenance may play a roll in this with 2nd or 3rd ownership as available funds decrease when it gets sold as a basic transportation.

Cheers,
GTM2u

dkozloski
05-04-05, 03:42 PM
Maybe we can find out how many Timesert kits and refill Timeserts have been sold. Maybe we could see if the company president drives a Cadillac. If it's a publicly held company somebody could buy some of the stock and force a disclosure.

mechanix
05-04-05, 04:34 PM
Not enough thread engagement, and not a large enough diameter for porous, cast aluminum threads. That's the problem as I see it. Even after timesert installation, you still have a steel fastener against cast, aluminum threads. Only now, you have more of it. And viola...problem solved!

For what it's worth, the parts man at my local GM dealership says that almost all the Caddies he sees come in for service are there for oil leaks, and very few for head gaskets.

gtm2u
05-04-05, 04:46 PM
Bbob has made reference to neoprene being used as part of the gasket sandwich for the supercharged North*. A quick check of the CRC Applied Science Handbook shows that the upper temperature service limit for neoprene is 100 Deg C. Maybe this is going to get really interesting. Hot rodders use solid or gas filled copper O-rings laid into a groove in the block or head. Maybe there is something to be learned here.

Hmmm, I've used aftermarket head gaskets which appeared to be a composition including neoprene but not as a laminate, more like homoginized blend. Seat of pants memory has that they started out life thicker than the normal gasket materials with a full metal ply. If your thumbnail is a Rockwell 4 these could be dented easily and did not have the same rigid structure. In all probibility they did crush to designated specs, however no follow up on my part was made to determine if they imposed a greater risk to leaking.

I've heard the arguments for highly machined block and head surfaces along with those who will machine degrees of a wavy texture in the head. Of the hundreds of engines I've done I cannot endorse one over the other. I would want to know more about the N* rigid sleeve vs a removable which could flex. The pictures I've seen of older N* blocks show no attemp was made to include grooves in the sealing face of the sleeve thus the gasket could move as things expanded.

You are right that those who wish to seriously improve the horsepower output of their engine will use an all metal gasket(s), depending on several factors they can select from different thicknesses and layers. However, perhaps because many are installed by DIY shade tree mechanics they do have what I would conclude an increased failure rate. I should also note that in most cases head bolts will have been replaced with studs with increased torque values (10-25%). I have long since passed the performance mods phase of my life and almost never on customer's cars, yet if I thought these were the solution I would have no qualms in using them if they were shown to be an improvement.

I suspect the neophrene used would be well above the 100C since road racing tires surly must exceed those temps on occasion for you don't get 7G's of cornering force without generating heat.

Cheers,
GTM2u

dkozloski
05-04-05, 05:44 PM
Also Neoprene is a specific rubber compound whose name has become generic for a whole host of rubber products. Nitrile, Buna-N, and the lord knows what. I don't think Neoprene has ever been used for tires.

ktills45
05-04-05, 06:03 PM
Has anyone researched CR for repair history on the N*? It should be pretty easy to spot engine problems related to head gaskets in their database.

gtm2u
05-04-05, 06:27 PM
Maybe we can find out how many Timesert kits and refill Timeserts have been sold. Maybe we could see if the company president drives a Cadillac. If it's a publicly held company somebody could buy some of the stock and force a disclosure.

I don't mean to discredit this as a possible source of valid info but we have read here from several participants that they only replace those which had damaged threads rather than a complete set of 20. Unless we can achieve some conclusion on what percent of failures this represents it may not be the best source.

I don't know who here can have a leg to stand on especially if they are like me who bought right. In my case knowing the possibility existed that the water pump failure could have caused a leaking head gasket or the other way around because of neglect. As an original owner with maint. records they would have a legit claim and could mount a class action demanding a writ of duces tacum from the supplier of an involved component such as the the head gaskets. This would probably not be met with much if any resistance since it's not proprietary info. Given that info, then the DOT would have records of vehicles sold which could be compared to other mfg. and gasket sales. I would not expect N* to willingly cooperate in disclosing any info which could expose that clearly a problem does exist. When I entered this thread it was met with that there is no problem, so there is the first stonewall red flag.

Not meaning to be insulting to those who have posted their dealer located in xyz doesn't sell head gaskets could be for a variety of reasons. When I was service manager I was privy to all the reigon's info from approx 40 dealerships. The monthly reports from the region were detailed and could be broken down to show percentages of unit repair. For those who don't know there is little profit in engine work and if a shop can get out of doing it they will pass it off onto other dealers with large shops and more skilled mechanics. Thus warranty or customer pay unit repair would be priced out of the shop or discouraged by stating we can't take your vehicle until next mont (slight exaggeration) but you could try dealer jwx for they may not be so busy. We had a fairly large shop with 22 mechanics and double stalls and I made it a practice of trying to hire only ASE certified mechanics with extensive licenses. This way a mechanic could be working on 2 cars including an engine while waiting for parts he could be doing tune-up so he didn't starve. My point is that the district would have more info than any single dealer on what parts were being sold and to some extent what work was being performed.

There are plenty of other factors including community and proximity to work, rental cars, driver service with pickup which will influence trends. Socio-economics play a roll in DIY repairs so dealers may be competing with chain auto parts and a small independent shops.

Cheers,
GTM2u

dkozloski
05-04-05, 07:00 PM
I think that a lot of this has to do with corporate culture and attitude. Among airline pilots Pan American guys were the very best, they carried themselves that way, and were the comsumate professionals. By the same tokin you could always tell them, but you couldn't tell them much. It looks to me that this spirit is alive and well at Cadillac. The caddy engineers are at the top of the GM pecking order. At the corporate luncheon they eat at the head table and the Chevy guys have a table in the kitchen. They appear to have a serious case of "not invented here syndrome." On the other hand they are the annointed ones and got where they are with results. Me thinks however that they are wrapped around the axle on this one.

gtm2u
05-04-05, 07:31 PM
I don't think Neoprene has ever been used for tires.

Aw c'mon dk don't you remember buying your tires at the local wrecking yard when you were a kid, or even better yet those you could find at the local dump for free, the ones that didn't have cracks on the sidewall always caught your eye. Other than a senior moment with polyester which had taken a vacation I'll be ok. ;)

Cheers,
GTM2u

dkozloski
05-04-05, 07:36 PM
Where in does the solution lie? It goes until the head cheese at Cadillac calls in the chief engineer on the carpet and tells him that he is tired of hearing about all this. It's time to get the best people on the job and if you don't get it taken care of before the sun goes down "I'm going to make your wife a widow and your house into a dung heap". Ben Johnson said, "It concentrates the mind wonderfully to know you are to be hanged in a fortnight". Nothing motivates like fear. Until then the stonewall persists.

ktills45
05-04-05, 07:56 PM
Not to continuously try to introduce statistics into this debate, but all the searches I've done on historical Cadillac Quality are turning up fairly decent reports on 3 year reliability of the drivetrain. By that I mean in the upper 20% of marks.

Again, instead of anecdotal evidence of mounting head gasket failures, has anyone searched for a CR database on Cadillac drivetrain reliability for the last 12 years?

Anyone with a CR account?

dkozloski
05-04-05, 09:15 PM
GTM2u, the tires I got from the wrecking yard had "S" numbers on 'em. The first graybeard doesn't have a chance.

dkozloski
05-04-05, 09:17 PM
ktills45, great idea. Anybody got an account?

gtm2u
05-04-05, 10:03 PM
Not to continuously try to introduce statistics into this debate, but all the searches I've done on historical Cadillac Quality are turning up fairly decent reports on 3 year reliability of the drivetrain. By that I mean in the upper 20% of marks.

Again, instead of anecdotal evidence of mounting head gasket failures, has anyone searched for a CR database on Cadillac drivetrain reliability for the last 12 years?

Anyone with a CR account?

ktills45: I for one don't know what a "CR" means much less have an account????? If you have something to contribute which can move this along to some finite end point I would be happy to hear it. What other options besides reporting their experience here even if it is in anecdotal format can be done in this thread. I'm not sure I would impose any structure or conditions how things get reported since there has been no structure nor was it intended to be a survey.
...................

Yes dk, nothing like High Noon or else, "don't believe me I'll just call 311 information and instantly recruit some engineers in India to replace you. Or I'll dial the 0 operator and be connected with the Philippines where all secondary education is in English."
..........
Whoosh, "S" numbers was that as in Senior... hehehe
..............

My source for a set of free engineering head studs claims that there was some misunderstanding and now wants me to pay almost $300 so I'm looking at other options. In my searches for alloys I came across the hydraulic/gas operated hood and trunk prop rods are made with some exotic metal. Anyone know what the rod metal is?? I just might look for someone to custom roll some threads if I supply the correct diameter rod stock? I also note that some of these new alloys do not have to be rolled to maintain their strength. Can't you just see it... Hello, Ace Hardware can I rent your power feed pipe threader for an hour...

Unfortunately my CNC lathe and mill are still waiting to be found.

Cheers,
GTM2u





Cheers,
GTM2u

ktills45
05-04-05, 10:29 PM
ktills45: I for one don't know what a "CR" means much less have an account????? If you have something to contribute which can move this along to some finite end point I would be happy to hear it. What other options besides reporting their experience here even if it is in anecdotal format can be done in this thread. I'm not sure I would impose any structure or conditions how things get reported since there has been no structure nor was it intended to be a survey.
...................

Yes dk, nothing like High Noon or else, "don't believe me I'll just call 311 information and instantly recruit some engineers in India to replace you. Or I'll dial the 0 operator and be connected with the Philippines where all secondary education is in English."
..........
Whoosh, "S" numbers was that as in Senior... hehehe
..............

My source for a set of free engineering head studs claims that there was some misunderstanding and now wants me to pay almost $300 so I'm looking at other options. In my searches for alloys I came across the hydraulic/gas operated hood and trunk prop rods are made with some exotic metal. Anyone know what the rod metal is?? I just might look for someone to custom roll some threads if I supply the correct diameter rod stock? I also note that some of these new alloys do not have to be rolled to maintain their strength. Can't you just see it... Hello, Ace Hardware can I rent your power feed pipe threader for an hour...

Unfortunately my CNC lathe and mill are still waiting to be found.

Cheers,
GTM2u





Cheers,
GTM2u

CR refers to Consumer Reports, the biggest collection of the most anal automobile owners on the planet.

If the N* is running higher rates of head gasket failures then other engines, this is where you'll find the information.

However, it is not a free site. You need an account to access historical data.

JD power indicates that through the 90's the Cadillac brand did pretty well with drivetrain issues relative to the auto industry in general, however the data isn't easy to compile in one report from that source.

I put alot more stock in statistical information then personal experiences when it comes to issues like auto reliability. Everyone has a horror story, however all that could mean is that we were victims of bad luck, not conspiratorial manufacturers.

dkozloski
05-04-05, 10:42 PM
Gotcha, "S" numbers as in a WWII coding system for tires that indicated the percentage of natural rubber contained therein. CR = Consumers Research.

dkozloski
05-04-05, 10:52 PM
ktills45, I agree that satistical evidence is required to quantify the problem but at least as the anecdotes keep rolling in Cadillac can't continue to claim that it's all a few isolated cases. Eventually they'll have to 'fess up. It seems like all these things like the Ford SUV's with Firestone tires, the Pinto gas tanks, and Chevy pickup tanks all started out this way. What we need is a rabid lawyer to start advertising on TV for people to sign up for a class action. He'll fight it right down to your last dime.

turbojimmy
05-04-05, 10:58 PM
CR refers to Consumer Reports, the biggest collection of the most anal automobile owners on the planet.

I have an account. Cadillac is well below average in reliability across the model line up.

Makes that rank above Caddy, in order from top to bottom are:
Scion
Lexus
Toyota
Subaru
Honda
Acura
Mitsubishi
Infiniti
Hyundai
Suzuki
Pontiac
Buick
Chevrolet
Jeep
Ford
Mercury
Mazda
Kia
Nissan
Chrysler
Dodge
Volvo
GMC
and Audi

Below Caddy, in order, are:
Porsche
Saturn
Saab
Mini
BMW
Lincoln
Volkswagen
Hummer
M-B
Jaguar
and Land Rover

I checked the Deville specifically and it's not spectacular. What's funny is that there is a category called "Engine". We all know the Northstar was substantially redesigned in 2000 and hasn't changed since then. The "Engine" ratings from 2000 to 2004 are as follows: Good, Fair, Very Good, Very Good, Excellent. All for the same engine.

I'm one of those anal automobile owners CR surveys every year.

Jim

edit: Forgot Scion at the top: all 3 Toyota brands round out the top 3 in reliability

ktills45
05-04-05, 11:09 PM
I have an account. Cadillac is well below average in reliability across the model line up.

Makes that rank above Caddy, in order from top to bottom are:
Lexus
Toyota
Subaru
Honda
Acura
Mitsubishi
Infiniti
Hyundai
Suzuki
Pontiac
Buick
Chevrolet
Jeep
Ford
Mercury
Mazda
Kia
Nissan
Chrysler
Dodge
Volvo
GMC
and Audi

Below Caddy, in order, are:
Porsche
Saturn
Saab
Mini
BMW
Lincoln
Volkswagen
Hummer
M-B
Jaguar
and Land Rover

I checked the Deville specifically and it's not spectacular. What's funny is that there is a category called "Engine". We all know the Northstar was substantially redesigned in 2000 and hasn't changed since then. The "Engine" ratings from 2000 to 2004 are as follows: Good, Fair, Very Good, Very Good, Excellent. All for the same engine.

I'm one of those anal automobile owners CR surveys every year.

Jim

How does the N* rate over the entire 90s?

Perhaps anal was a bit harsh....:p

turbojimmy
05-04-05, 11:13 PM
How does the N* rate over the entire 90s?

Perhaps anal was a bit harsh....:p

Not at all. They only ask me because I subscribe. I am anal about automobiles so I like to think I'm a good respondent. A car is a huge investment so I take the time to answer the surveys.

I'll see what I can dig up on the N* in the 90s.

Jim

Stoneage_Caddy
05-04-05, 11:21 PM
I have an account. Cadillac is well below average in reliability across the model line up.

Makes that rank above Caddy, in order from top to bottom are:
Scion
Lexus
Toyota
Subaru
Honda
Acura
Mitsubishi
Infiniti
Hyundai
Suzuki
Pontiac
Buick
Chevrolet
Jeep
Ford
Mercury
Mazda
Kia
Nissan
Chrysler
Dodge
Volvo
GMC
and Audi

Below Caddy, in order, are:
Porsche
Saturn
Saab
Mini
BMW
Lincoln
Volkswagen
Hummer
M-B
Jaguar
and Land Rover

I checked the Deville specifically and it's not spectacular. What's funny is that there is a category called "Engine". We all know the Northstar was substantially redesigned in 2000 and hasn't changed since then. The "Engine" ratings from 2000 to 2004 are as follows: Good, Fair, Very Good, Very Good, Excellent. All for the same engine.

I'm one of those anal automobile owners CR surveys every year.

Jim

edit: Forgot Scion at the top: all 3 Toyota brands round out the top 3 in reliability
All the toyota brands are at the top , but only one (scion)doesnt have the V6 that toyota has had to swap out or repair on a almost epidemic basis for oil sludgeing or the early to mid 90s fisaco ont he v6 engines int he trucks with serious headgasket issues , one service writer recalls one t100 need a headgasket before its first oil change LOL ....

scion ....arent they less than a year old ....

so they arent all "clean" ...

and there is still an issue with the headgaskets thats about as odd and freqent as the 2.2 turbo chrysler headgaskets (ok thats a bit harsh)...which you could set your watch by ....well maybe not but 3 i encoutnered all blew out at 107k...

so the northstar could be worse ...it could be a beemer nikisil or a 2.2 chryler that destorys the head when it blows the gasket .....

blb
05-05-05, 12:02 AM
All the toyota brands are at the top , but only one (scion)doesnt have the V6 engines int he trucks with serious headgasket issues , one service writer recalls one t100 need a headgasket before its first oil change LOL ....



Toyota is at the top, not because their cars are all flawless, but because when there are problems, the dealer will replace and/or repair whatever needs to be done, without charge and without hassle when common and chronic problems are known to exist. My coworker had his '94 V6 Toyota pickup at the dealer for an oil change back in 2000 when the dealer noticed a slight problem (nothing apparent to the owner) with one of the headgaskets and replaced both free of charge......and this is when the vehicle was 6 years old with 124,000 miles! The vehicle now has 285,000 miles with no issues.

Now try taking a 6 year old, 124,000 mile Northstar to a GM dealer that is overheating and leaving plumes of white smoke out the exhaust and ask them to repair it for free. They will either laugh at you or tell you "they all do that". (maybe not that far from the truth after all..... LOL)

That's why folks, GM is now in serious financial trouble and Toyota is enjoying double digit sales gains for the year.

dkozloski
05-05-05, 02:40 AM
One thing about it, this problem is not anything that is going away soon. I'll bet the Cadillac engineers go into the morning meetings sweating like Jim Bakker's cell mate. They have to know there is one hell of a problem and the lid is coming off sooner or later. Meanwhile the company strategy is, Deny! Deny! Deny!

turbojimmy
05-05-05, 06:29 AM
Toyota is at the top, not because their cars are all flawless, but because when there are problems, the dealer will replace and/or repair whatever needs to be done, without charge and without hassle when common and chronic problems are known to exist.

First let me say that I don't necessarily agree with the rankings, I had access to them so I reported them. The rankings I put up are for new car reliability. Getting at older stuff is difficult because you can't compare manufacturer vs. manufacturer. You have to pick a make and model and then view the results one at a time.

Like I said, I fill out the surveys every year. These aren't magazine writers, industry 'experts', manufacturers or anyone else who could potentially be biased. The results are from real people who bought the cars and who filled out the survey. Some folks might have a particular affection for a certain brand, but I think overall the results are a pretty good indication of what to expect when you buy a particular car.

That being said, it's apparent that the US automakers still aren't doing it right in the eyes of the consumer. It's the consumer who will ultimately determine their fate - not magazine writers or industry experts.

Jim

ktills45
05-05-05, 07:37 AM
I also know of someone who owned a Toyota who had a control module go bad and the dealer replaced it free of charge after the car was out of warrenty.

However, since most of us are in some type of business where we get paid for the work we do and have to charge for the cost of parts and labor, I would like an explanation of how Toyota dealers, not the manufacturer, but the guys selling and maintaining the cars, can absorb all these extra costs without comment or complaint.

And I'll admit to some confusion over the issue being debated here.

Is the contention that N* that are over 100k miles blow head gaskets, and that this is a design flaw? Or that N* which are under warrenty routinely need service for this problem?

ktills45
05-05-05, 07:41 AM
BTW, regarding unstable temps....


My N* runs between 190 and 230, depending on whether I'm idling in traffic on a hot day, or I'm out moving on the open road.

My CTS temp indicator spins up to 1/2 on the gauge and doesn't move at all regardless of whether I'm going 60 on a winter day or sitting on the Schullkyll in the middle of the summer.

You tell me which is more accurate. :suspect:

gtm2u
05-05-05, 07:47 AM
One thing about it, this problem is not anything that is going away soon.
...
They have to know there is one hell of a problem and the lid is coming off sooner or later. Meanwhile the company strategy is, Deny! Deny! Deny!

You got that right, as more of these thing rack up miles or stress it's not going away. I would like to see warrany claims vs units produced vs years involved. Blown head gaskets, oil leaks, are all considered smog related along with leaking hazardous waste on our roadways. I might try the Calif. Bureau of Automotive Repair for they handle customer disputes with shops and dealers.

What I have never understood is how mfgs. keep things like this from being a recall. I know sometimes when grave problems exist which could possibly bankrupt a company they will not enforce the laws. A very famous case involving GM back in the 1940's(?) was kept from the public until the 60's was the conspiracy with GM, Standard Oil, and Goodyear tires (think I have all the names right) who bankrupted the passenger rail system here in Los Angeles so they could sell more cars, tires and gasoline. The courts determined that had they imposed fines for the loss of public transportation would have ruined all three companies and bankurpted them. This is the reason why LA has the worst public transit system in the country.
................

I think the denial we have seen here is just what can be expected at all levels. The bean counters know how long they can stall / delay to the point cars can safely be excluded from any legit claim on the Federal mandate of 5 & 50. Most assuredly the Japanese makers have bent over backwards in comparison to Detroit's approach where it seems everything is met with a fight when it's obvious something is wrong.

How many major block and head revisions are there, 93-94, 95-97-99, 00-04? And the parts are not interchangable as best I can determine.

Cheers,
GTM2u

ktills45
05-05-05, 08:01 AM
"The lid is going to come off...???"

Perhaps turbojimmy could explain better, but I believe an average rating for CR indicates a 5% or so rate of problems with a specific part on a car.

The 2000-04 model run of the N* seems to be well below that for mechanical problems, so I'm not entirely sure what lid is coming off where.

turbojimmy
05-05-05, 09:08 AM
"The lid is going to come off...???"

Perhaps turbojimmy could explain better, but I believe an average rating for CR indicates a 5% or so rate of problems with a specific part on a car.

It's not obvious to me what the average rate of problems is based on their chart. What they do is set the average number of problems at '0' and plot everyone around that center point. Again, what the average is I don't know. It's really pretty interesting. They slice and dice the data all different ways - not just by manufacturer but by size of the car, type, etc. They also provide longer term reliability projections. For example, their data shows that minivans and large SUVs deteriorate at a faster rate than cars and pickups.

They also show an 8-year reliability trend. Asian cars are way ahead with about 70 problems per 100 vehicles after 8 years; American cars show about 135 problems per 100 vehicles after 8 years. Average is 120 problems.

Anyhow, I don't think I answered the original question with all the data. Sorry if I've muddied the water even further. After checking out the various Cadillac models for the past 5 years, engine complaints don't seem to be significant. CR even calls the Northstar "superb". Overall reliability is low, but it does not necessarily seem to be engine-related.

Jim

gtm2u
05-05-05, 09:08 AM
I also know of someone who owned a Toyota who had a control module go bad
...
I would like an explanation of how Toyota dealers, not the manufacturer, but the guys selling and maintaining the cars, can absorb all these extra costs without comment or complaint.
...
And I'll admit to some confusion over the issue being debated here.
Is the contention that N* that are over 100k miles blow head gaskets, and that this is a design flaw? Or that N* which are under warrenty routinely need service for this problem?

I'll take a stab at some of this. First, there may have been some sort of a unwritten recall on the item which for some reason the customer was informed the car could have this done at no charge. There are advantages to taking a car to a dealership for repairs or service. That aside if it's a loyal customer the service manager has the descrition of checking that little box that says "customer good will", now he can do this with or without prior approval from the District Service Manager. If the DSM rejects the claim he has the choice of appeal or just eating the loss for he just won a customer.

The Japanese when they moved into the US market knew they had to compete with Detroit and besides including a heater and radio for free, they had to woo their customers they just stole away from Detroit. Their profit margin was very low and warrany claims were high so they didn't loose that newly won customer. And as basic as it may seem they have pride in their work which is a cultural heritage. That's a broad sweep of the brush but for the most part still accurate since day one.
...............................

To some extent the 100k-130k miles seems to be where a lot of failures are occuring. There are some with 75k and less which have reported failure, these were covered under an extenced warrany or customer good will. Without a doubt it is a design problem which can be repaired but at horrible expense... $2,500 - $4,000+ which is more than some of the cars are worth.

No, not something which is just going to be done because you came in for a tune up unless you reported problems with overheat and/or coolant loss. I don't think there is any solid info on what brings this on other than driving the car. The problem is the bolt size and thread pitch when used on an aluminum block was not adequate to hold the heads down tight. Standard engineering practice of using a coarse thread into aluminum was ignored and thus the aluminum tore out the threads. By no means do I mean to suggest I am a Cadillac expert, however I have been working on all aluminum engines for over 40 years and know what engineering standards should have been used. In theory the design engineers should have learned this in their 1st or 2nd year of school.

Cheers,
GTM2u

ktills45
05-05-05, 10:02 AM
GT, I agree with your Asian analysis completely.

My friend with the Toyota has reported problems with every one he's owned, yet the service he recieves convinces him that his car is fantastic. Customer service is the single biggest problem with Detroit imho.

However, I would have to disagree with your analysis of the N*. According to Turbojimmy, CR rates this engine very highly, with few mechanical problems. Apparently, design flaws are not the primary culprit behind the head gasket failures, and those failures are not showing up in the numbers that have been suggested by members of this forum.

ktills45
05-05-05, 10:28 AM
I believe the N* was designed from the get go as an all aluminum engine which could and would survive a complete loss of engine coolant without destroying the engine. At the time of it's introduction, was there any other engine in the world of similar design making that claim?

My point is that to assume that the engineers made 2nd year mistakes in designing the bolts or thread patterns of same when they had set out to specifically study engine performance absent cooling liquid, of which the major manifestation would be head failure, defies belief. Maybe bbob's N* was the one and only engine that they ran dry, and maybe it was the one and only engine that they based the entire research program on, but I think that we could agree that this scenario is also straining the limits of credulity.

We now have some data regarding the historical reliability of the N*. CR hands out the word 'superb' in describing American cars about as often as comets strike Manhattan, so I believe that we can infer that the N* does not suffer a higher degree of head gasket failure then any other engine, and most likely it has fewer problems then most.

mechanix
05-05-05, 11:06 AM
N* engines are prone to head gasket failure at any time. I know one individual who lost his engine at 5,000 miles! GM simply replaced it with a new crate motor, free of charge.

It is common knowledge that magazine articles tend to favor the products that advertise with them or give other compensation. Consumer Reports, as I understand, claims to be unbiased, but do we really know for sure? I guess the only way we will ever know what percentage of N* engines fail is to conduct our own, independent study.

The percentage on this forum seems to be very high. But it must be remembered that almost all of the contributors to this forum are Cadillac owners who are experiencing problems. The contented owner who has never had a problem with his Caddy would probably have no reason to seek out this forum and contribute to it.

dkozloski
05-05-05, 11:42 AM
The idea of designing out random troubles in an engine is pretty rediculous but here we are describing the same scenario over and over and over. This is exactly the kind of trouble that you try to uncover by keeping failure data and having it analyzed. What has happened at cadillac is that they have decided that the design is "good enough", they can keep a lid on it, and spare the expense and loss of face of an admission and fix. Because some minor changes have been made they are aware of and are trying to address the problem under the radar with questionable effectiveness. Good is the enemy of great. Where you would think that Cadillac would like to have the reputation of putting out great engines, thay have settled for good. The really pitiful part is that they are just one failure mode away from a great engine but are content to let it all slip away in the chase for the almighty dollar.

ktills45
05-05-05, 11:45 AM
N* engines are prone to head gasket failure at any time. I know one individual who lost his engine at 5,000 miles! GM simply replaced it with a new crate motor, free of charge.

It is common knowledge that magazine articles tend to favor the products that advertise with them or give other compensation. Consumer Reports, as I understand, claims to be unbiased, but do we really know for sure? I guess the only way we will ever know what percentage of N* engines fail is to conduct our own, independent study.

The percentage on this forum seems to be very high. But it must be remembered that almost all of the contributors to this forum are Cadillac owners who are experiencing problems. The contented owner who has never had a problem with his Caddy would probably have no reason to seek out this forum and contribute to it.

But do you know a statistically meaningful sample of people who have suffered head gasket failures to offer anything except personal experience to the debate? Do you know anyone driving a N* without having head gasket failure? Do you know 5? Does that matter?

The reason I asked for data from CR (Thanks for your time, TJ) was because CR doesn't take advertising dollars. A cursory read of their auto reviews would make you believe that if they did it would all be in yen and not greenbacks. However, absent some other reliable metric, they are the database of record. Your personal experiences may vary, however when a large cross section of owners are polled, the apparent answer is that head gasket failure is so rare as to not show up on the most critical of automotive surveys.

As for this forum having a high number of head gasket failures, according to the limited participation in this thread, it would not appear as if this is a huge problem even for the forum members. Perhaps a poll is in order, or has one already been taken?

ktills45
05-05-05, 11:47 AM
The idea of designing out random troubles in an engine is pretty rediculous but here we are describing the same scenario over and over and over. This is exactly the kind of trouble that you try to uncover by keeping failure data and having it analyzed. What has happened at cadillac is that they have decided that the design is "good enough", they can keep a lid on it, and spare the expense and loss of face of an admission and fix. Because some minor changes have been made they are aware of and are trying to address the problem under the radar with questionable effectiveness. Good is the enemy of great. Where you would think that Cadillac would like to have the reputation of putting out great engines, thay have settled for good. The really pitiful part is that they are just one failure mode away from a great engine but are content to let it all slip away in the chase for the almighty dollar.

I honestly don't know how you can post this, unless you have data that is contrary to the limited amount that has already been offered.

dkozloski
05-05-05, 11:57 AM
ktills45, I admit the evidence is circumstantial but it is all there for the world to see. First we have the identical failures that go on and on. Then we have the limited response and minor modifications. Finally we have deny, deny deny. For motives I have selected greed, self preservation, and vanity. This same scenario has been played out on the world's stage countless times. It remains to be seen how badly it bites them.

turbojimmy
05-05-05, 12:11 PM
As for this forum having a high number of head gasket failures, according to the limited participation in this thread, it would not appear as if this is a huge problem even for the forum members. Perhaps a poll is in order, or has one already been taken?

I don't think it would be a very objective poll. Many people do come here looking for help with problems. I'd guess you'd wind up with a figure for failures that doesn't really reflect reality among the hundreds of thousands of Northstars sold whose owners don't come here.

It is hard to ignore what seems like a comparatively high number of head gasket failures in this population, though. I'd say fewer members of turbobuick.com have popped head gaskets which is pretty incredible (a byproduct of increased boost is often a blown head gasket).

On the other hand, as one of those people that CR surveys, I have faith in the CR data and frankly I'm surprised that the Northstar engine ratings were so high. They don't rate any make or model without a minimum of 100 completed surveys. Again, while Cadillac quality in general is below average, respondents indicate that the reliability problems are in areas other than "Engine", primarily electrical, brakes and suspension.

We have 3 N* engines in the family with varying miles on them. I'm keeping my fingers crossed anyway.

Jim

ktills45
05-05-05, 12:15 PM
ktills45, I admit the evidence is circumstantial but it is all there for the world to see. First we have the identical failures that go on and on. Then we have the limited response and minor modifications. Finally we have deny, deny deny. For motives I have selected greed, self preservation, and vanity. This same scenario has been played out on the world's stage countless times. It remains to be seen how badly it bites them.

Saying something you believe to be true does not make it so.

As a counterpoint, I offer the data from CR. That data is there for the world to see, and they call the N* superb. I highly doubt that an engine with an inordinate amount of head gasket failures would earn that superlative.

GT says that most hg failures occur 50 to 80k miles after the warrenty runs out on the vehicle. :hmm: And even then, it's certainly not EVERY vehicle. However, based on no more information then this, he says that this failure rate is the result of a design flaw.

Look, I'm not calling anyone's mechanical competence into question on this issue, I'm certainly not expert enough to do so even if I wanted to. What I am trying to find out is what the vast majority of owners experience. The only two credible resources for that type of information are JD Power and CR. Both tend to give the N* high marks for reliability, so I'm inclined to believe that the design of the engine was pretty good.

dkozloski
05-05-05, 12:24 PM
I read years ago in CR that the most reliable engine ever put in a car was the Phase II Mazda RX-7 Rotary(1986+). O.1%(1 in 1000) of the owners reported engine troubles of any kind including running out of gas. The average milage that the trouble was reported at was 168,000. This was reported following a long term study. If CR is getting 100 responses for a typical model year they could completely miss a 1% failure rate for the same problem which is deplorable. A 1% failure rate if the failures are random is one thing, but if they are all the same it's a scandal but also easily missed with a limited sample.

ktills45
05-05-05, 12:34 PM
I read years ago in CR that the most reliable engine ever put in a car was the Phase II Mazda RX-7 Rotary(1986+). O.1%(1 in 1000) of the owners reported engine troubles of any kind including running out of gas. The average milage that the trouble was reported at was 168,000. This was reported following a long term study. If CR is getting 100 responses for a typical model year they could completely miss a 1% failure rate for the same problem which is deplorable. A 1% failure rate if the failures are random is one thing, but if they are all the same it's a scandal but also easily missed with a limited sample.

Fair enough, but by the same token you're accepting anecdotal evidence as a basis for making conspiracy claims against Cadillac while ignoring the only factual information available.

dkozloski
05-05-05, 12:38 PM
The big stickler is that the failures are the same and thus with a little effort could be addressed. A low failure rate is of no consequence until it happens to you. What galls is when you ask around and find out you are not alone but because it doesn't make the 6:00 news you are stuck with a turkey that will be difficult to justify the repairs. Cadillac tells you that you are an isolated case when in the office and a mechanic tells you out back that you have been a pigeon as you prepare to drag the carcass home for a DIY project.

turbojimmy
05-05-05, 12:40 PM
If CR is getting 100 responses for a typical model year they could completely miss a 1% failure rate for the same problem which is deplorable.

They require a minimum of 100 in order to post the data. I would venture to guess that they've gathered substantially more than 100 responses on just about any make, model or year they select. You have to set a minimum somewhere.

Jim

mechanix
05-05-05, 12:44 PM
Personally, I don't really care what the percentage of N* failures are. Mine failed, and I had to fix it. I also know that a lot of others do too. So what? End of story.

But I certainly agree with what DKoz says about GM, and (Detroit in general) selling out quality for profit. There was a time, in the thirties, when quality mattered. But automakers like Duesenberg, Packard and LaSalle went broke doing it. We are not likely to see American automakers make that mistake again in our lifetime. Unfortunate, but that's life in the corporate world! *lol*

ktills45
05-05-05, 12:44 PM
BTW, I just did a search on Cars.com.


Within 100 miles of my house, there are 300+ Cadillacs for sale under 10k dollars. There are 5 RX-7's for sale at any price in the same area.

When it comes to statistical sampling, I think Cadillac will have more accurate reporting data under the CR method then the Mazda.

Stoneage_Caddy
05-05-05, 01:10 PM
well comapreing the very trusty non turbo 13b rotary to a Northstar isnt fair to boot....think about how many more parts that old northstar has comapred to a rotary ....turbo rotarys are a diffrent story , i dont see many running around witht he original engine , theve pretty much been replaced at some point ....whatever happens hurts the rotor houseings because i hardly find one with a rebuilt .....

I would would venture to say that the more parts the more chance of a failure as far as a numbers game is conerned ....

but if that was the case alone the pushrod 4.9 would be more prone to failure than the northstar ....

blb
05-05-05, 01:36 PM
What has happened at cadillac is that they have decided that the design is "good enough", they can keep a lid on it, and spare the expense and loss of face of an admission and fix. Because some minor changes have been made they are aware of and are trying to address the problem under the radar with questionable effectiveness. Good is the enemy of great. Where you would think that Cadillac would like to have the reputation of putting out great engines, thay have settled for good. The really pitiful part is that they are just one failure mode away from a great engine but are content to let it all slip away in the chase for the almighty dollar.

Very well said!

1996deVille
05-05-05, 01:36 PM
It is the sample that disturbs me.

Most of these cars are still purchased by "older" drivers. Now, that curve is changing b/c of the Babyboomers, so the 40's group has become more active in buying a Caddy...

So the question becomes length of ownership vs. longevity over time (with engine problems) - in other words, if you rate your N* from 0 to 50K the numbers will be good. But most buyers trade these cars in before 50K and the used market takes the brunt of design characteristics, like head gasket failure, A/C failure, blower motor failure, and on and on.

That's our problem as buyers, let us beware!

BUT, the challange I see is the mean, mode, and median of how Caddy designs these cars. The Bell Curve that exists for us to deal with sets in motion the set of design flaws we find after 50K - in fact, they have determined that since most people purchase new cars and trade in at mile "X" then the design must work for "X" miles. After that point, well, here we are 14 pages into problems with the N* platform.

I want a car that runs w/o major problems for 100K. Just basic maint. My dad's '68 GMC was the last GM product in our family to do this - unfortunately, he later bought Japanese and these cars went well past 100K w/o major problems.

I will do everything I can to drive an American car, but with the attitude and designed limitation built into my '96 Caddy, I don't know how long I can afford to stay with American mfg. I don't like dealing with depreciation near 50% in a couple years to avoid problems. I guess that's the ultimate decision when we step foot on the Caddy lot.

These are adequate cars for 50K or about 4 years, no longer.

dkozloski
05-05-05, 01:39 PM
I wasn't holding up the Mazda as a standard but as an example of the available data and to provide a little perspective.
Any production engineer will tell you that the very cheapest way to produce anything made from metal is with pressure die castings(permanent mold). The down sides of this process are porosity from trapped air, unstable metal grain structure from the metal being disturbed in the cooling process, cracks, distortion, mixed hardness, built in stresses, and probably a lot of others. He will also tell you that if you want the highest quality aluminum castings you better plan on sand casting. The metal cools much more slowly and is better able to move around and fill the voids. The porosity of the sand allows the air to escape everywhere to control porosity and you don't have the sudden chilling that promotes warpage and distortion. Some of the downsides are it is expensive and labor intensive. Instead of trapped air you can have trapped loose sand which rips the tooling. The end product requires more machining and there is a higher scrap rate. Plus there is the sand inside to break up and remove. That being said, long and intensive research and developement can produce a permanent mold casting line that produces good engines but for an investment of tens of millions if not hundreds of millions of dollars. Where the cheese binds is if very late in the game you find a problem that requires redesign of the mold. This can cost millions with permanent molds and a few swipes of a pocket knife with a sand mold. Each process has its advantages and disadvantages. Cadillac chose the bigger investment with the prospects of a payoff in the long run but also a big chance of trouble cropping up. Making these choices is why they make the big bucks.

dkozloski
05-05-05, 02:01 PM
1996 DeVille, a very good take. The pressure is to make it last "long enough". Rather than quality for qualities sake it is all broken down to economics and the bottom line. This is what makes America great but it hurts when it is your car in the driveway with a pool of liquid under it.

BeelzeBob
05-05-05, 02:11 PM
dkoz...I forget....have you personally had a head gasket problem with a Northstar or are all the comments you make about failed head gaskets from what you read on the forum, here?? I honestly don't remember if you posted about a problem you had or if you even have a Northstar. Just too many posts under the bridge...LOL.

dkozloski
05-05-05, 02:51 PM
Bbob, I have a CTS with a 3.6L VVT. It has been flawless. One of my coworkers has a North* with the infamous head gasket problem that he is about to tackle. I'm sure there is much to be learned there. I have to admit however that I really don't have a dog in this fight. My sympathies to those that do. BS aside, Cadillac must have torn down enough of these things, examined the pulled threads with an electron microscope, sawed them up with a bandsaw, x-rayed, measured clamp loads, chemically analyzed gaskets at the point of failure, and every other testing process known in the civilized world to the point that they know exactly what's happening just like the FAA and NTSB do after an air disaster. At least I would hope so. I also know that this is proprietary information that they are free to keep under control because it doesn't involve safety. It's the secrecy that disturbs the public and the feeling that the public is being "played". The fact remains that even if the failure rate is low there is a commonality that indicates it could be made to be go to zero with the proper motivation. It's all a matter of economics. You can never find a good whistle blower when you need one. LOL

ktills45
05-05-05, 03:07 PM
Hehe, I go out running with the dog and come back to this. :D


Mech, the idea behind a design flaw is that it will result in a much higher then average failure rate. An average failure rate or below average failure rate would invalidate the claim of a design flaw. Therefore, the absolute numbers of head gasket failures relative to the industry in general is critical to the understanding of the problem. Also, do a google search on JD Power. GM is currently ranked 4th in the world for quality, out of 20 manufacturers. If they would dump Saab and Hummer they would probably be in first. :canttalk:

dkozloski
05-05-05, 03:07 PM
One of the beauties of having quality and process control as good as Cadillacs is that when the problems show up they can be quickly evaluated, narrowed down and identified. That is the whole idea of data collection and analysis. Now the trouble shooters, who are usually your best people, are put to the task of stomping out the brush fire before it gets out of hand. Meanwhile the bean counters decide if it's all worth it. All manufacturers have to decide for themselves how far they are willing to push the issue of quality. Some day this will all blow over when the next issue arises and takes the heat off the head gasket group.LOL

dkozloski
05-05-05, 03:16 PM
ktills45, your premise holds true only if you accept as fact that there is no way to cure a recurring failure just because no one before you has succeeded. With this attitude we'd still be doing tuneups every 10,000 miles and there'd be people alongside the road patching their own flat tires just like we did when I was a kid. It seems to be a part of life that the better you do the more is expected of you. In that regard, Cadillac has become a victim of their own success.

ktills45
05-05-05, 03:57 PM
ktills45, your premise holds true only if you accept as fact that there is no way to cure a recurring failure just because no one before you has succeeded. With this attitude we'd still be doing tuneups every 10,000 miles and there'd be people alongside the road patching their own flat tires just like we did when I was a kid. It seems to be a part of life that the better you do the more is expected of you. In that regard, Cadillac has become a victim of their own success.

:)

Ok, I can agree with the sentiment here.

However, I'll offer your and my 'flawless' 3.6L CTS's as proof that Cadillac is taking what you say to heart.

Bbob, thanks to you and all the folks at Lansing Grand River for making such a great car. :thumbsup:

dkozloski
05-05-05, 04:33 PM
It must come as a pretty solid blow to an engineer when a project that he puts his heart and soul into hits a snag. The tendency to become defensive and blame the end user is only natural. I know how I felt when someone had trouble with an aircraft engine that came out of my shop. It fact one of the reasons I got out of that racket was that I no longer wanted the exposure of the possibility of having blood on my hands from a mistake. I succeeded and came out clean. That being said, the concept of zero defects is a good one. It looks to me like Cadillac has the goal within their grasp and only needs to finish the deal.

ktills45
05-05-05, 04:38 PM
It must come as a pretty solid blow to an engineer when a project that he puts his heart and soul into hits a snag. The tendency to become defensive and blame the end user is only natural. I know how I felt when someone had trouble with an aircraft engine that came out of my shop. It fact one of the reasons I got out of that racket was that I no longer wanted the exposure of the possibility of having blood on my hands from a mistake. I succeeded and came out clean. That being said, the concept of zero defects is a good one. It looks to me like Cadillac has the goal within their grasp and only needs to finish the deal.

Hehe.

An aluminum engine which will run without coolant for an extended period of time and was designed 14 years ago which occasionally blows out head gaskets after 100k miles would hardly be called 'hitting a snag".

But I agree that if there is a fix, let's do it.

BeelzeBob
05-05-05, 04:50 PM
What has happened at cadillac is that they have decided that the design is "good enough", they can keep a lid on it, and spare the expense and loss of face of an admission and fix. Because some minor changes have been made they are aware of and are trying to address the problem under the radar with questionable effectiveness. Good is the enemy of great. Where you would think that Cadillac would like to have the reputation of putting out great engines, thay have settled for good. The really pitiful part is that they are just one failure mode away from a great engine but are content to let it all slip away in the chase for the almighty dollar.




Please don't take my previous question in the wrong way...(about whether dkoz has had personal experience with a Northstar head gasket failure)....I just wanted to bring the interesting facts to life that the two biggest proponents of bashing Cadillac for Northstar head gasket problems, dkoz and gtm2u, that have kept this thread alive all this time have neither had a problem with a Northstar head gasket.....hmmm.....now who was just accusing ME of being an "internet expert"....

I know dkoz hasn't had a problem because of his honest answer and I have asked gmt2u twice and the fact that he hasn't lambasted me with the story of his failure indicates that he hasn't had one either. So....eliminating the "noise" from this conversation would tone things down a bit.

I don't mind a good arguement...in fact I like to argue. You learn a lot that way especially if you take the time to argue to opposite case to see what they have up their sleeve....LOL I just don't like the incessant piling on in this thread and repeatitive nonsense about how Cadillac "cheaped out" and how they are perpetrating a hoax on the public by selling Northstar engines, etc.

There are really not that many head gasket failures on Northstar engines out in the field. I have said this time and time again. It is backed up by my own experience and the circumstantial warranty and service parts sales rates of certain parts. There are millions of Northstar engines in the field. Many of them have WAY over 100K on them with no problem what so ever. They are NOT the weak kneed, head gasket blowing engines that some would portray. In fact, the fact that they still run like they are brand new with 100K and 150K and 200K on them is almost to their disadvantage as people seem to think that they should ALL run forever. Making statements and accusations and drawing conclusions from what you come across in this internet forum is NOT scientific. All you see is the majority of posters that are seraching out this forum because now they have a problem. So all you see are the problems.

Head gasket failures on Northstar engines are NOT epidemic. Yes, some engines , depending on their service history and maintenance procedures will start to loose a head gasket with 100K and 150K and 200K on them. Do they ALL do that...??? NO. Do many of them do that...??? NO. Does this indicate that Cadillac "cheaped out"...???....NO. Does it condemn the engine...????...NO.

People read this thread and get worked into hysterics about head gasket failures being rampant and what it will take to REDESIGN the engine to make it stop blowing head gaskets. And some of the most hysteric and voiciferous about it have never even had one......LOL LOL. All the other 99.9% of Northstar owners are out driving around enjoying the weather.

There has been ample recognition that the head gasket joint in the Northstar can be improved upon as evidenced by the increased head bolt thread engagement in the block, revised head bolt thread pitch change for the 2004 concurrent with the RWD engines, the use of the multilayer steel head gasket design for the Supercharged Northstar for the STS-V and XLR-V.

This is a funny deal...damned if you do and damned if you don't. Improve the joint thru ongoing product improvement and increasing HP levels and some say it is proof that the design was flawed. If we didn't change it then people would say we were not accounting for the additional power we were making in the engine...LOL All designs evolve and improve over time. If they didn't , cars would not get airbags because it would "prove" that they were unsafe before them, etc.... Get used to it. It doesn't mean that things were bad before but that things can get better.

When the Northstar engine went into production in 1992 calender year it was still a bit of a stretch to expect all engines to last 100K miles without a hiccup. Today, 13 years later it is more expected. And the engines of today, manufactured today, will last much longer. But that doesn't apply retroactively to 13 year old engines in the field. Most of the people doing all the bitching have bought the cars for a fraction of what they cost new with close to 100K on them and they complain about a conspiracy....LOL. Get real. The fact that the engine inside is like new and is easily repairable when it breaks should be a feather in the cap of the engineers that worked on it yet some would tar and feather them for an occasional failure in a gasket after 100K.

Sorry for this rant. I just read one too many posts about this..... LOL

dkozloski
05-05-05, 05:02 PM
Bbob, you're as right as you can be. As I said in an earlier post, Cadillac is a victim of their own success. Now we expect perfection. FWIW, as far as running a liquid cooled engine without the coolant. Teledyne Continental makes a liquid coooled aircraft engine called the LIO-550. It passed the full certification testing with all the coolant drained out of it. This included all the full power runs. They were as surprised as anyone. The object of the exercise was to find out how long the pilot would have if all the water was lost which is a certification requirement. It turns out that the complete loss of coolant is a non event. The engine is partially aircooled with water jacketing on the cylinder heads and upper cylinder areas and aircooling fins near the cylinder bases.

dkozloski
05-05-05, 05:23 PM
Bbob, because the North* head gasket fix requires the use of an expensive and hard to find Timesert kit that compensates for a known weakness in the original design and because as you state there are only a few isolated failures, why wouldn't Cadillac want to meet the unfortunate customers with failures halfway with a program where the dealer would Timesert for free any block brought in by an individual owner. This would go a long ways towards making the customer whole again. This is not without precedent. Many years ago as a kid I worked in a service station. My boss's wife had a six year old Caddy. One morning on startup it threw a rod that stapled the block to the pan with the big end. I disassembled the engine and found that a nut had unscrewed from a rod bolt. I gave the pieces to my boss and he mailed them to GM just for the hell of it. Six months later after I had picked up a junkyard motor, rebuilt it, and installed it he got a call from the local dealer to come get his new motor. GM had shipped him a fan to flywheel crate motor free of charge even though it was years out of warranty.

haymaker
05-05-05, 05:41 PM
Thanks for the model and picts, my '94 has a head thickness of 3.0" from washer seat to head gasket. My bolt hole depth is 3.17" with a bolt length of 5.48".

I see no reason to not use as much of that 3.17" depth as physically practical. The Timesert is .500" O/D so why not to forget the insert and tap for a 1/2"x13 N/C stud 6.75" long? It's not violating the block anymore than the insert, it's in keeping with the later coarse thread which should have been employed in the beginning, however it does require drilling the head bolt out .038". What's your take on this?
Ok gtm2u I was analyzing your plan to replace the 11 mm head bolts with ½”x13 NC studs and found these potential problems.
1. The recommended drill size for an ½”x 13 N/C tap is 0.422” and the original 11 mm x 1.5 female threads in the block, at their O.D. are at a minimum of 0.440”. So just removing the old threads in preparation for the thread tapping will make the hole oversized. Then of course you may have the head bolts that bring the female block threads out of the hole as they are removed during disassembly making the diameter of those holes even larger than the 0.440” dimension. Both instances above would result in less than ideal thread engagement, in other words the stud would be a loose fit in the female block threads.
2. The area of the bolt hole just above the female threads up to the block deck is factory drilled to a larger diameter 0.475+” and useless as an area for additional threads to increase the thread engagement for use with the ½”x13 NC stud. It looks as though to increase the thread engagement in the block one would need to drill then tap the area below the original female block threads (the area below the bottom end of the original head bolt) and by doing so possibly gaining 5/16” or so of additional thread engagement for your stud. IMHO the original threaded portion of the hole is too large for a good fit of the ½” x 13 NC tap and may not yield any real gain toward strengthening the joint. The only way to prove the studs will or will not work is to install them. Worse case, the new female threads in the block fail, you pull the engine again and install the big-serts or you could save some time and money by installing the big-serts the first time. After reading your posts I get the impression that you feel the original 11 mm head bolt is the problem because it’s too weak but I on the other hand think it is the problem because it is too strong. IMHO it would be interesting to try a new head bolt sized at the original 11 mm in the threaded area then reduced in diameter to 9.5 mm for the entire length of the shank in hopes the head bolt would then yield enough to save the head gasket and female block threads during a 270 degree overheat yet be strong enough to survive a few hundred thousand miles of normal driving. BTW the original head bolt shank diameter is 10 mm but the threads are rolled at a larger 11 mm diameter, just in case anyone was wondering. Guess that’s enough of the armchair engineering for one day. Like I said before in an earlier post the dimensions I have posted are biased on measurements from my ’97 N* and all drill/tap sizing from one of my drill/tap charts. The N* dimensions and drill/tap sizing chart you have may differ slightly

ktills45
05-05-05, 05:48 PM
Bbob, because the North* head gasket fix requires the use of an expensive and hard to find Timesert kit that compensates for a known weakness in the original design and because as you state there are only a few isolated failures, why wouldn't Cadillac want to meet the unfortunate customers with failures halfway with a program where the dealer would Timesert for free any block brought in by an individual owner. This would go a long ways towards making the customer whole again. This is not without precedent. Many years ago as a kid I worked in a service station. My boss's wife had a six year old Caddy. One morning on startup it threw a rod that stapled the block to the pan with the big end. I disassembled the engine and found that a nut had unscrewed from a rod bolt. I gave the pieces to my boss and he mailed them to GM just for the hell of it. Six months later after I had picked up a junkyard motor, rebuilt it, and installed it he got a call from the local dealer to come get his new motor. GM had shipped him a fan to flywheel crate motor free of charge even though it was years out of warranty.

The known weakness you're referring to is the bolts, I assume?

While you're at it, Bbob, my suspension needs work. How about having Cadillac pitch in for some new shocks? I only have 131k on these, I suspect you all can do better then that. :histeric:

dkozloski
05-05-05, 07:08 PM
The weakness is the threads in the block which the Timeserts address.

BeelzeBob
05-05-05, 10:43 PM
The Timesert kit is neither hard to find nor that expensive. Really, now. Tell me how much you paid for that last set of Snap-On combo wrenches and then, with a straight face, tell me how expensive the timesert kit is. Something that a mechanic that is qualified to work on these engines should have I would say....just like a torque-angle wrench or any other tool. The mechanic should buy the kit and charge the customer for the inserts used.

Repairing threads in tapped hole is not something that can be predicted as a failure. There are many heads removed and reinstalled without timeserting...I have seen a LOT of them done that way during development. I would assume that timeserting the holes after 100K is part of normal wear and tear in my personal opinion. Have "Cadillac" timesert blocks that people bring in...??? That would be more difficult and expensive than just doing the job in the garage it is in in many cases.

Besides...until I mentioned Timeserts on this forum several years ago no one had even heard of them...much less some of the dealer techs that chimed in. Even though they are clearly called out in the original Northstar service manuals and were/are available from Kent Moore (GM specialty tool supplier) I still get arguments that "GM said to use helicoils" which we know don't work in this case and is NOT what GM said. So...who are we going to send them to to have them timeserted...??? Bring them to Detroit so I can do them in my garage...??? LOL LOL

I still think that the instance of actual failed threads is much lower than you expect. I really do not believe from what I have seen that the block threads failing are the root cause of the head gasket leaking. It may happen in one or two cases here or there but it is not the overwhelming problem thatn you suppose. Whether the head gasket fails from corrosion, excess thermal fatigue a severe overheat, whatever...I suspect that the head gasket starts to leak and then the engine comes apart and a head bolt hole is damaged or the threads are damaged at removal from galvanic action causing the thread to stick and gall and remove some of the female aluminum threads. We have plowed this before. This phenomenon happens in ALL aluminum threads if the joint is together long enough. Normal wear and tear. That is what mechanics do...fix things. If it involves repairing a thread so be it. I have personally watched techs ruin the threads in the block by "cleaning" them out with a cutting tap and ruin them by running a round wire brush into them with a drill motor to "clean" them. They are often ruined by not cleaning at all and galling old material into the aluminum threads with the new bolts. Of course, when this happens, the tech blames the crummy threads in the block...

Granted, with 10-12 years on the engine and 100K on the clock I think that it is good insurance to timesert the block but it really isn't required all the time. You guys have created as much hysteria over timeserts as you have over head gaskets in general with all the talk. There are timesert experts on here that have never SEEN one....LOL.

BeelzeBob
05-05-05, 11:01 PM
Believe me, the weakness is NOT in the bolts. Those are excellent bolts that are carefully controlled metallurgy and heat treat to provide the high loads required to seal the head and hold the combustion loads. Their length is designed for adequate stretch during thermal cycling so as to not overload the head bolt and crush the gasket substraight. I would LOVE for someone to show me a broken head bolt. They do not exist.

Unless....the owner puts straight DexCool in the system. We did have a rash of broken head bolts from one specific operation that was traced to pure DexCool in the cooling system of those cars. In that case the head bolts actually snapped in two right in the middle of the bolt. We were dumbfounded seeing one as no one had ever seen a bolt fail like that or a broken head bolt period. Usually a bolt will break in the thread section if it is overloaded. In this case, after examination, the failure was due to a stress corrosion failure causing a pit in the shank of the bolt resulting in a stress riser that lead to the failure. The pure, acidic, DexCool leeched sufficient acidic vapor into the head bolt cavity thru the pores in the gasket to create a corrosive environment that lead to the stress corrosion failure that is common in high alloy bolts under high stress. It was purely due to the neat DexCool that was not mixed 50/50. I guess that operator thought that straight coolant , DexCool or otherwise, was better than 50/50 specified. Those were very unusual cases (they had more than one car with neat DexCool in it...) and were restricted to the cars with the staight DexCool.


The head bolt load balance is the thing that I keep warning about with the idea of changing to studs or some larger bolt. The head gasket can only take a finite amount of load...about 70 to 75 kiloNewtons per bolt without permanently deforming and collapsing or loosing its resiliency or ability to spring back and maintain load as the engine thermal cycles. The load changes during thermal cycling are well understood and the gasket and bolts are designed to provide enough load to seal and contain combustion, stretch during heat cycles and retain sufficient resiliency to seal cold. If that balance is upset, like with stiffer "stronger" studs the head gasket will fail that much faster. Try it...you'll see.

There are special head gaskets made that have pzieso-electric transducers mounted throughout them so that it is possible to map out the loads in the gasket as the head bolts are pulled down and the block is thermal cycled. Those were used extensively, as well as the sonic bolt length measuring equipment to measure the bolt stretch, to quantify the parameters required for sealing the head gasket on the Northstar.

This type of work lead to the multilayer steel gasket on the supercharged engine. Due to the increased cylinder pressures the loads on the gaskets from the bolts needed to increase which would have over-loaded the existing compacted graphite gaskets. The MLS gaskets can take more initial preload from the bolts and maintain their resiliency so they were incorporated into the design. The compacted graphite style gaskets are still desireable as they provide superior micro seal for containing liquids (coolant) and they do not need as fine a surface finish as the MLS gaskets do which makes it easier to prep the deck surface on the NA engines.

BTW...per an earlier comment made...I would NOT consider glass beading or "roughing up" the deck faces for better gasket retention. That will tear the gasket up ver quickly as the parts thermal cycle.

gtm2u
05-05-05, 11:27 PM
Ok gtm2u I was analyzing your plan to replace the 11 mm head bolts with ½”x13 NC studs and found these potential problems.
1. The recommended drill size for an ½”x 13 N/C tap is 0.422” and the original 11 mm x 1.5 female threads in the block, at their O.D. are at a minimum of 0.440”. So just removing the old threads in preparation for the thread tapping will make the hole oversized.
...
The N* dimensions and drill/tap sizing chart you have may differ slightly

Hopefully the attachment made it, if not I can upload to my "Webshots" picts.

Here are my measurments for the '94 N* STS, using the Timesert which measures .505" O/D but it's still a 1.5 pitch (see attached file) If the new engines are 12mm with a 2.0 pitch that is .472" so a 1/2" would be larger by .028". However the head fastner hole needs to be drilled to a fat .500" for bolt or stud.

Measurments [G] and [H] may not give full thread contact for the entire length of the re-thread if taken to the 1/2" bolt/stud. Before I commit to any of this I want to put my Borescope down the holes and examine the existing thread integrity.

Cheers,
GTM2u

dkozloski
05-05-05, 11:38 PM
Bbob, I need a little more explanation about the bolts. I realize the bolts don't break but it looks to me that since they are the same minor thread diameter the entire length that when they are stressed in the block the load will not be evenly distributed down all the threads in engagement. Something has to give between the threads in the top and the bottom of the hole just as if the thread pitch was wrong in order to load up the threads at the bottom. What I am used to seeing is cap screws that have a much reduced diameter between the head and the first thread so that the major part of the stretch will take place there and there will be a much smaller stretch through the thread engagement section because it is much stronger. This makes the stress on the threads more equal. These bolts have rolled threads and are made from forged blanks. An example of their use is aircraft wheel halves and R-3350 Curtis-Wright cylinder hold down bolts. It's probably a cost issue.

BeelzeBob
05-06-05, 01:08 AM
Theoretically I agree with you. Practically it doesn't seem to be a problem. We talked about this before mentioning the aircraft ($$$$) fasteners that actually have a variable pitch on the threads so as to perfectly load each thread. That also requires a very specific tap to make the female threads to match and it is extremely impractical with our method of rolling or forging the female threads in the block. We have tested different bolt shank diameters during development for the engine back in the late 80's and early 90's and found excessive elongation with smaller shanks. The bolt sizes that we have today were the result of that work.

I agree to some extent that as the bolt is loaded or tensioned the thread area must elongate somewhat to accomodate the stretch but that hasn't seemed to be a practical problem. I suspect that we are probably near the limit of the thread engagement that we could use (about 3 diameters currently) without going to that type of scheme. One that that does work around that to some extent is the fact that we prestress the aluminum threads in the block by pulling the bolts down to a slighlty higher load and then spinning them back out and retensioning for the final time. The aluminum threads are very tight due to the rolling form and the design of the threads so they are close to an interference fit the first time the bolt is run down and tensioned. After the "pretenioning" step the threads accomodate the different stretched lenght along the thread due to the working of the aluminum thread form during the pre-tension step. We found a noticable improvement in pullout loads by doing the pre-tension step and then loosening and repulling the bolts down.

Circumstantial evidence of this is frequently/always seen when we destructively test head bolt threads in the engine plant. All 20 Head bolts are installed thru a dummy spacer plate and torqued to failure. If the aluminum thread pulls out it is an obvious bad sign. This is not the only check on the threads but serves as a go/no go on each machined lot of blocks to quickly check for anything going amiss during the head bolt thread machining operations. It has proven to be very good at catching problems as we will always snap the head bolt at the top first thread as it is pulled into an over-torque situation. Appearances are from this that the threads are loading fairly uniformly in the aluminum as one can usually take a screw driver and remove the broken piece of bolt. The bolt breaks where predicted and the aluminum threads are not deformed so that the piece comes out easily. I have seen LOTS of head bolts snapped of like this in auditing blocks. If the heat treat on the bolts is faulty you will typically see the head of the bolt snap off but I have only seen that on specific lots of bolts with alternate hardening during developement.

gtm2u
05-06-05, 01:09 AM
Please don't take my previous question in the wrong way...(about whether dkoz has had personal experience with a Northstar head gasket failure)....I just wanted to bring the interesting facts to life that the two biggest proponents of bashing Cadillac for Northstar head gasket problems, dkoz and gtm2u, that have kept this thread alive all this time have neither had a problem with a Northstar head gasket.....hmmm.....now who was just accusing ME of being an "internet expert"....

I know dkoz hasn't had a problem because of his honest answer and I have asked gmt2u twice and the fact that he hasn't lambasted me with the story of his failure indicates that he hasn't had one either. So....eliminating the "noise" from this conversation would tone things down a bit.

I don't mind a good arguement...in fact I like to argue.
...

Sorry for this rant. I just read one too many posts about this..... LOL

bbob:

Selective reading and retention will keep getting you into trouble.

Someplace in the first 2-3 posts I suspect a blown headgasket mention existed, that not withstanding it could be inferred from several other posts.

I have a blown head gasket!

A 2 mile stretch of 4% uphill grade after the engine is at operating temp will use _2_ gallons of water. By the time I get to the next off ramp the temp is 250-253 degrees, never went into fail safe mode. I no longer make any trip over 5-8 miles on flat level streets. Market, Post Office, hardware store runs with traffic signals the water use is confined to 1-2 pints and temps below boiling. I have yet to install the 180 T'stat which may or may not help reduce this usage. The fact that when driven in traffic conditions with these short runs is limited water use I am prepared to replace the bolts with larger studs with or without inserts. I have succesfully done it before on other engines and am willing to do it again. I think my mechanic skills are vastly superior to yours especially since I do things rather than say it can't be done. I notice you had no retort when I contradicted your shade tree block check method that I've only seen suggested by rank amatures.
.......................

There is a hell of a big difference from mounting personal attacks and a good argument, you obviously missed that class in school. I'll eat your merda when you can prove that the failure rate on these torn threads and blown head gaskets is 1%. It isn't an accident that the 11mm 1.5 pitch bolt diameter has been changed to a 12mm and a 2.0 pitch. I can't imagine that with a 1% failure rate they would consider such a drastic change IF there were NOT a problem. Goodness knows they tried everything else but the obvious.
.................

I've asked before what _is_ the tensile strength of the aluminum block?? If it is not the repeated bolt stretch tearing threads then WHAT is causing them to get torn... crankshaft?? Act decently and you will get a response, act as you have, put it where the moon don't shine. You can fool some of the people some of the time ~

GTM2u








There

BeelzeBob
05-06-05, 01:16 AM
GTM2U....I keep responding to you politely and I get a tirade back from (if I get a response at all) about how stupid I am. I have news for you... I am not stupid. And I don't need caps yelling at me or two foot high letters to read your occasional responses. Just type it out nice and plain and we can all read.

Just cut the chatter and BS at me and stifle your attempts to clean me up and talk about the engine and parts.

First that I have read anywhere that you have a head gasket problem despite asking twice before.

BTW...the bolt diameter wasn't changed ...just the thread pitch. As I indicated , if you read my post above, the thread pitch was upgraded to accomodate increasing power levels (some of us knew about the supercharger before the public did). It does not imply that the joint was bad before. It is just an ongoing improvement as the motor makes more power. If you use your logic no one could ever change a design because it would be "proof" that the previous design was flawed. Improvement in a part does not mean that the previous generation piece was bad.

BeelzeBob
05-06-05, 01:26 AM
You know, GMT2U , you are the one that continues with the incessant barbs and attacks. You can't even let up in your last post without putting several in there. I am really trying to be nice and respond to you accurately and civily. Please do the same.

As far as retorts....I must have missed that one. Exactly what shade tree block check was I proposing that you castigated. Maybe we can start there if you could simply describe it to me. Speaking of a selective memory....what about all the nonsense about the head bolts not having enough load to hold combustion and such....LOL Maybe we both have selective memories.

You must realize that you are not the only one that has been around the block a few times. Just because what I say or propose does not fit YOUR preconceived notions does not mean that it is wrong or that I am making fun of you. I get crap from people on here constantly that like to dish it out on me because they have a beef with GM so I get pretty good at dishing it back at people like you . Lighten up and talk about parts and engines and we can communicate but I will not continue to listen to your lecturing me.

BTW....I scanned back thru your posts looking for the block check that I was an idiot for suggesting and I haven't found it nor any mention by you about your head gasket failure....so that is why I kept asking. It isn't my selective memory in that case...it was lack of mention and no response by you.

BeelzeBob
05-06-05, 01:59 AM
So...gmt2...I read back thru all the posts and I'm still at a loss...

" I notice you had no retort when I contradicted your shade tree block check method that I've only seen suggested by rank amatures."

What are we talking about here??


BTW....click on your name and click on "find all posts" and read thru yours in order. And you are chastising me for name calling and such. Really. You need to look in a mirror. LOL LOL

gtm2u
05-06-05, 02:01 AM
Theoretically I agree with you. Practically it doesn't seem to be a problem. We talked about this before mentioning the aircraft ($$$$) fasteners that actually have a variable pitch on the threads so as to perfectly load each thread. That also requires a very specific tap to make the female threads to match and it is extremely impractical with our method of rolling or forging the female threads in the block. We have tested different bolt shank diameters during development for the engine back in the late 80's and early 90's and found excessive elongation with smaller shanks. The bolt sizes that we have today were the result of that work.

I agree to some extent that as the bolt is loaded or tensioned the thread area must elongate somewhat to accomodate the stretch but that hasn't seemed to be a practical problem. I suspect that we are probably near the limit of the thread engagement that we could use (about 3 diameters currently) without going to that type of scheme. One that that does work around that to some extent is the fact that we prestress the aluminum threads in the block by pulling the bolts down to a slighlty higher load and then spinning them back out and retensioning for the final time. The aluminum threads are very tight due to the rolling form and the design of the threads so they are close to an interference fit the first time the bolt is run down and tensioned. After the "pretenioning" step the threads accomodate the different stretched lenght along the thread due to the working of the aluminum thread form during the pre-tension step. We found a noticable improvement in pullout loads by doing the pre-tension step and then loosening and repulling the bolts down.

Circumstantial evidence of this is frequently/always seen when we destructively test head bolt threads in the engine plant. All 20 Head bolts are installed thru a dummy spacer plate and torqued to failure. If the aluminum thread pulls out it is an obvious bad sign. This is not the only check on the threads but serves as a go/no go on each machined lot of blocks to quickly check for anything going amiss during the head bolt thread machining operations. It has proven to be very good at catching problems as we will always snap the head bolt at the top first thread as it is pulled into an over-torque situation. Appearances are from this that the threads are loading fairly uniformly in the aluminum as one can usually take a screw driver and remove the broken piece of bolt. The bolt breaks where predicted and the aluminum threads are not deformed so that the piece comes out easily. I have seen LOTS of head bolts snapped of like this in auditing blocks. If the heat treat on the bolts is faulty you will typically see the head of the bolt snap off but I have only seen that on specific lots of bolts with alternate hardening during developement.

bbob that is worth quoting the complete post for it represents what should have been stated weeks ago. I am capable of reading between the lines and also note the mention of current production context and tongue in cheek in other places.

I refused to answer because you could not distinguish between personal attacks / hung on evey word to screw with me rather than a rational discussion. Act with respect and you will receive respect.
..............

I am surprised at the breaking with the last thread and I would ask for clarification. I'm not exactly clear if the break was at the last thread on the shank or where it actually engaged the block?? You indicated you could tease it out with a screwdriver suggesting that the current design(?) is able to hold the bolt 90,000(?) psi tensile without distorting even the first thread.
........................

BTW Shouting is using all caps, stressed is CALLING attention to specific content just _as_ using underscore can be just as effective.

GTM2u

dkozloski
05-06-05, 02:04 AM
Bbob, I am now satisfied with the bolts and the block checking process but I have to ask if you have tried cadmium plate with a chromate wash for the bolts to minimize corrosion in the threads. You just never see this in aircraft engines except in exhaust studs. I disagree with GTM2u's estimate of a 1% failure rate 1 per 100. Estimating from the number of members on the forum and the number of posts complaining it looks more like 0.1% or 1 per thousand. I suggested that Cadillac help the people with failures with the Timeserts because this is the one step that makes the head gasket repair different from the ordinary and would present some difficulty to the average bear DIYer. Also there is some evidence that there was or still is something going on here to create the pulled threads that is a little beyond the normal wear and tear. If I presumed wrongly that Cadillac should feel some obligation to a customer in a world of hurt from a process that quite likely they are responsible for please pardon me all to hell.

BeelzeBob
05-06-05, 02:10 AM
gmt2u...you're right, I wasn't clear on which "last thread" When torqued to failure the head bolts will snap at the thread adjacent to the shank of the bolt...the farthest thread from the end of the bolt. Usually it will snap thru the closest thread starting at the root of the thread about 2/3 of a turn from where the thread originates.


dkoz...no, cadium and chrome are no-no's for environmental reasons. They have been out for years on automotive fasteners. Just don't consider them because they are not allowed. Geez...now you are getting touchy...you mentioned one approach to the timesert issue, I suggested another. I guess at some point one has to draw the line and move on.

gtm2u
05-06-05, 02:34 AM
Bbob, I am now satisfied with the bolts and the block checking process but I have to ask if you have tried cadmium plate with a chromate wash for the bolts to minimize corrosion in the threads.
...

I suggested that Cadillac help the people with failures with the Timeserts because this is the one step that makes the head gasket repair different from the ordinary and would present some difficulty to the average bear DIYer.
...
Also there is some evidence that there was or still is something going on here to create the pulled threads that is a little beyond the normal wear and tear. If I presumed wrongly that Cadillac should feel some obligation to a customer in a world of hurt from a process that quite likely they are responsible for please pardon me all to hell.

dk, I was of the impression there is a problem with Cad plating and aluminum, not clear on the chromate wash though that might yield an aluminum salt under these conditions. I know chrome primer is used prior to painting because of a mild etch is desirable, however, we have other factors which are going on that might be why it's considered a no no. ??
.......................

While it would be nice if some consideration would be given I know the chances are a snowball chance in hell for 3rd owner. I'm looking to flate rate an ugly job with enough safty margin that I won't have to worry. And the only thing I can count on is my past experience that has not let me down with customer's cars or my own. I am not the only person who has done this and know it's valid. The iffy part is the integrity of the gasket after the few radical overheats that I know of. I know I can feel the loss of compression in power output and hear the difference on 4 & 6 cylr engines but V8 mask these so well it's difficult to spot how bad it really is.

To that end I was wanting as much info as was available, if there is some problem which will guarantee failure then I won't consider it but to this point I've not been presented with those arguments.

Cheers,
GTM2u

gtm2u
05-06-05, 02:40 AM
gmt2u...you're right, I wasn't clear on which "last thread" When torqued to failure the head bolts will snap at the thread adjacent to the shank of the bolt...the farthest thread from the end of the bolt. Usually it will snap thru the closest thread starting at the root of the thread about 2/3 of a turn from where the thread originates.


That's what I thought you meant and close examination with an eye loupe suggests that if it had been faired over 2-3 threads might have changed results. Wasn't that Lord Witworth's research as well as the radius on the underside of bolt heads to prevent failure?

dkozloski
05-06-05, 02:40 AM
Bbob, I'm not being touchy, just a wise ass. At least I am now convinced that cad and chrome is the answer so we can blame the whole deal on the EPA.
Gtm2u, look for NAS studs if you want to go down that road. They have fine threads on one end, coarse on the other and are made in a multitude of lengths and sizes. Rolled threads and 180,000PSI on up. Cad plated with a chrome wash. See your banker for a loan first. They match up with 12 point nuts with equal strength.

BeelzeBob
05-06-05, 02:45 AM
So...gmt2...I read back thru all the posts and I'm still at a loss...

" I notice you had no retort when I contradicted your shade tree block check method that I've only seen suggested by rank amatures."

What are we talking about here??




Maybe I figured it out.... I mentioned the check for a blown head gasket of pressurizing the cylinder with shop air thru the spark plug port using an old spark plug as an adapter.

Is that the "block check" that you are referring to as shade tree...??? Am I getting warm..??

Then you propose the poster use one of three checks that you like , the colored solution, the sniffer in the surge tank or the expensive sniffer in the surge tank.

And I didn't retort.


Guess I didn't think I needed to. All of them will work to some extent. In my experience with several different engine development programs the order of accuracy in determining a head gasket leak is 1. pressurize the chamber 2. use a sniffer in the rad or surge tank 3. Don't bother with the colored solution as it doesn't work with some coolants, it has false positives and false negatives that I have seen myself. That test is basically worse than a waste of time as it is misleading sometimes.

The standard gasketing industry test is to pressurize the joint. Period. That most closely replicates what the joint is doing. Pressurizing the head gasket thru the spark plug port to establish leak rate is a standard check at any point on a development engine. Ask anyone in the gasket industry that does that type of work. We typically use nitrogen at 2000 PSI regulated to the appropriate pressure for the specific gasket. Any gasket development lag in the world will have dry nitrogen bottles around for leak testing. 2000 PSI nitrogen can make anything leak....even the tightest head gasket. Usually a check is made at 700 PSI nitrogen but even at that level the head gasket can be damaged or misleading leak rates can be established as the combustion pressures are so short lived that true leak rate at the joint is best approximated by a lower pressure holding for a longer period of time.

Is pressurizing the head gasket joint with shop air thru a chopped up spark plug shade tree. Hell yes. That IS what we are talking about here when someone asks how to check their head gasket. Since most posters on here are working under a shade tree (figuratively or really) then a simple check like that is very appropriate. Is that an accurate check...YES...shadetree or not. It is the single positive test of head gasket integrity. Do it with the engine cold as that is when head gasket leaks are the worst due to the engine being cold and the load on the head bolts being mininum due to the shrinkage of the block and head structure. Pressurize it and watch the cooling system for bubbles. Works flawlessly every time. You should try it.

The nice thing is that it is so easy. Grind the rolled ring off of an old spark plug shell. 90 seconds on the grinder the porcelean is out and in your hand. On a Northstar plug you can run a 1/8 pipe tap into the plug shell from the backside without even drilling it. Screw a length of 1/8 pipe nipple in for an extension and pop an air quick connect on the end and you're done. I made two the other night for spares as I had given my last ones away.


The issue and inaccuracy of the sniffer tests for combustion gases is that the engine must be running and will get hot so the block/head structure expands and adds load to the gasket. I know that most head gasket leaks manifest themselves pulling a hill but that is because the cylinder pressure is the highest, not because the engine is hot. You cannot replicate the high cylinder pressures idling in the garage. If the head gasket leak is very slight, it will probably not show up on a sniffer due to the hot engine and the light load idling in the garage. It may show up but it is NOT conclusive. Been there, done that. Seen it happen. Clean on the sniffer and bubbles at 120 PSI in the chamber.

The colored liquid and test strips for combustion gases work sometimes but they are not conclusive from what I have seen. Our guys just do not bother with them as they will end up doing a pressure lead test of the chamber for positive results so we just go straight to that. Several of the test strips like that specifically say to not use with DexCool or other OAT coolants as the coolant color and the coolant acidity throws the test off.

Granted, our pressure checks might be a bit more scientific with nitrogen at higher pressures and such but 120 PSI shop air thru the spark plug port is just as effective, simple, easy and cheap. No reason not to like it. If it is shade tree to you so be it.....but it works and works well and I will continue to recommend it as the ONE way to validate the head gaskets for leaks or not.

That is the point of checks like this, isn't it?? It might be shade tree in description but it has sound engineering logic behind it and it has sound practical experience behind it. It is something that anyone that has a compressor and can change spark plugs can do, it is easy to describe and convey and it is dead reliable. The other checks require expensive equipment and are not that reliable from what I have seen and for sound engineering logic in that you cannot duplicate the high cylinder pressures underload sitting in the garage.

Lots of mechanics use leak down checks to establish the health and sealing capability of rings and valves. The test proposed is simply an extension of a leak down check...albeit with highe pressure and not orificed restriction and using the coolant ssytem much like you would use the wash tub for finding the leak in a tire. Works every time. Yet to see it fail.

Later dudes. Good chat. Got to go to bed. Michigan time here and I have to go to work tomorrow. LOL

dkozloski
05-06-05, 03:04 AM
GMT2u, the cad plate folowed by the chromate wash protects the bolt without the aluminum sacrificing to the plating. This has been standard practice in the aircraft industry since the late 1920's.

1996deVille
05-06-05, 12:17 PM
Bbob,

To be clear, my '96 has just turned 115K with no head gasket failure. Unless the head gasket was changed before I bought this car (probably not) this is still the original part. No complaints from me on this... I got my 100K+ so anything from this point on is money in the bank!

I'm a fosil, I want to just pull the carb (shows my age) and intake, loosen the exhaust manifold and pull the head - slap the new head gasket on, retorque everything and drive off! I don't want to pull the body off the frame to get to the head gaskets.

So, engineer me a switch that reconfigures the car to RWD when I need to do this job, and back to FWD upon the last torqued bolt... that's all, just a little button somewhere, anywhere.

I'm just whinning...

Much success!

BeelzeBob
05-06-05, 02:08 PM
Having to pull the engine/trans/cradle is part of the deal with the current generation of FWD cars. When those cars were being engineered eons ago the serviceability issue was a big concern. Service engineering considered them "un serviceable" and so did the dealerships. They got over it. Todays generation of mechanics considers it "normal" to drop the cradle. It is certainly not the easiest thing to do at home but it is actually not that difficult with a hoist and the proper equipment. The greater difficulty in service is more than offset in my mind by the added durability and reliability of the overall packages. There is just precious little need to pull the drivetrain anymore. Not like it needs an "overhaul" every 50K or so.

As an understanding also of the RWD/drop the cradle mentality....don't think it is any easier with todays RWD cars. You aren't going to go in there and pull the heads or remove the engine easily. Cars are built differently than they were decades ago.

Across the automotive industry there is a distinct shift in the way the cars are assembled which affects the serviceablity and dictates the service procedures. In the ancient times, when cars had full frames and such, the chassis was assembled with all the running gear and the engine was dropped in from the top. In some cars the body went on first and then the engine/trans and then the front fenders and in others the engine was in the chassis before the body was dropped onto it and then the fenders/hood were installed. This ended with the last of production of the RWD Fleetwood/Chevy Caprice type cars. Trucks and SUV's are still assembled this way. Cars, however, are universally frame integral or "uni-body" construction. The engine compartment structure is part of the body and the front structure/radiator cradle/fenders/etc... are all "there" when the body is welded and bonded together. The engine/trans or engine/transaxle is subassembled to the engine cradle and the entire engine/trans/front suspension is stuffed into the engine compartment from below. Everything on the engine/trans/cradle has to fit thru the opening in the lower part of the engine compartment so that it can clear when it is installed from below. since this is the way it is designed and the way it is assembled it is naturely the way to service it. Trying to design a frame integral structure for the engine compartment in a car that would allow installation of the engine/trans/driveline from above is virtually impossible. So it isn't just some engineer's nightmare to make it hard to service. The whole thing is driven by the vehicle architecture that has the least compromises for the task at hand.

BeelzeBob
05-06-05, 02:58 PM
At least I am now convinced that cad and chrome is the answer so we can blame the whole deal on the EPA.


Yep, the EPA certainly did put the stop to any use of chrome or cad in the auto industry. Especially on fasteners and other engine parts. Lead (as was used in bearing shells) is also taboo.

I am still not quite sure of what you are blaming on what or what is going to fix what...??? The coating you mention might or might not help with any bonding of the bolt to the theads in the aluminum. I don't have any direct experince with the cad or chrome finish described (by default since we don't use it) but the head bolts are finished with a phos and oil coating that provides a reasonable level of protection on normal fasteners that are exposed to the elements otherwise. The head bolts are not simply plain steel that are uncoated. They are coated with the phosphate and impregnated with oil prior to having the microencapsulated loctite compound applied to the threads. The loctite compound acts as a high pressure lubricant AND then a thread locking agent. The loctite product used is an anearobic compound that only sets up after any oxygen has been sealed out of the joint. So....the head bolt joint as it is today has a reasonable anti-corrosion coating on it AND it is sealed at the thread interface with the loctite sealante AND it is in it's own sealed/dry cavity. I just don't know exactly how much better you are going to get or expect the thread interface to be with another coating only. ( we covered this aspect before, right??)

gtm2u
05-06-05, 04:13 PM
...
Is that the "block check" that you are referring to as shade tree...??? Am I getting warm..??

Then you propose the poster use one of three checks that you like , the colored solution, the sniffer in the surge tank or the expensive sniffer in the surge tank.
...


I would be interested to know if any _factory_ produced manual endorses the use of compressed air to check for a head gasket leak. ?? I have taught/trained dozens upon dozens of mechanics in classroom and in the shop on the job and never endorsed this procedure as being reliable.

What must be remembered is that mechanics cannot afford to be wrong for their very bread and butter is based on accurately diagnosing any problem. The shop's reputation is dependent on this accuracy, peer pressure, jub security are all on the line. Sure you can find "mechanics" who may try to diagnose a blown headgasket using this method, I've seen the shot gun approach as well where an incompetent mechanic will misdiagnose a blown head gasket only to pull the head and find it's not been leaking and then has to "sell" another repair. You want to see a service advisor go through the roof, pull that crap on them.

Not meaning to be contentious but there is a line from the guy that has to fix these problems and the people that design them. The engineer's lab is not the same as the real world whereas we have a whole population who are resentful that they have to spend money on their car. I cited one failure to properly diagnose a car which eventually required them to leave it overnight. This is not the standard of the industry, a car comes in complaining of water loss and you do a block check on a customer wait basis. Some shops including radiator specialty may or may not charge for this service. I have never worked for any repair facility where the customer was told the car had to be left so it could be checked with a cold engine. Some shops own the tools, some require the mechanic to own them. The fact that now some of the chain parts stores rent them because it's in their interest to sell parts should be an indicator.

I've tried injecting freon into the system with no success, I should also mention that using the compressed air method requires that every cylr must be checked. So you are not talking about a 5 minute test which may prove nothing. Sure having a reliable 2,000 psi air source but would you want to turn that loose on the average mechanic. Go to a scuba dive shop and see what the law requires... What happens when you have a blown gasket and the cooling system sees this continuous 2,000 psi rather than the fraction of a second from combustion. The water column inertia would probably blow the radiator into hundreds of pieces.

The real world depends on what we do to make the day for both customer and the mechanic. This country needs competent PROFESSIONAL mechanics and not parts changers, this may not be as profitable to the mfgs but the day will come again.

Cheers,
GTM2u

BeelzeBob
05-06-05, 04:13 PM
It isn't an accident that the 11mm 1.5 pitch bolt diameter has been changed to a 12mm and a 2.0 pitch. I can't imagine that with a 1% failure rate they would consider such a drastic change IF there were NOT a problem. Goodness knows they tried everything else but the obvious.




gmt2u....back to this topic. There must be some confusion from what you saw and from what I said.

The head bolt size has not changed. I meant to elaborate on that last night but forgot about it. So...some of your conclusions here about what a "drastic change" might be indicating are a bit premature or erroneous.

The head bolts that have been in use on the Northstar from 1993 thru 2003 are roughly 11 mm bolts. As are any custom made bolts they are slightly outside the normal range of "standard" sizes for shank diameters. If anything, they are on the large side of an 11 mm bolt. They are 11mm X 1.5 mm pitch.

The headbolts on the Northstar beginning in 2004 model year are still 11 mm bolts but with a 2.0 pitch which is a "non-standard" pitch for this size bolt so they are bastards in a fashion. The bolt size has not changed to 12 mm as you state. If fact, when you take one of the 11 X 1.5 bolts and measure the shank diameter you will find that (gasp) the 11 X 2.0 bolts are actually slightly SMALLER than the earlier bolts. This is because the thread rolling form and the amount of material upset with the coarser 2.0 thread pitch.

So...any conclusions about Cadillac "admitting" that the bolts were too small was a bit premature. The bolts are still the same size, albeit incrementally smaller in the shank with the 2.0 pitch.

Least everyone jump on the bandwagon of the coarse pitch fastener and think that it is a panacea understand that it creates it's own issues with a much greater propensity to loosen during thermal cycling...it requires a more aggressive loctite material to hold it in place. Also, since the thread pitch is more coarse the "angle" part of the fastening sequence becomes more stringent due to the greater percentage of stretch associated with each degree of rotation of the bolt.


Which brings me to something else stated earlier in one of your posts that needs clearing up. You mentioned that Cadillac was using the torque angle procedure which the fastener industry had abandoned long ago. I since verified and posted that the fastener industry was still "on that bandwagon" as you put it....and no retort from you...!!! What means of fastener tightening strategy do you like or trust or feel is in vogue at the current time that we should be using or investigating. Seriously. Everyone that I know of uses torque-angle for critical fasteners as the angle of tightening can be directly correlated to the bolt stretch whereas pure torque is very dependent on friction in the threads and under the head of the fastener and can be very misleading. There are some thru bolts that are tensioned by dimensional criteria...i.e...direct measurement of bolt stretch with a bolt mic (typically things like con rod bolts) where access to both ends of the fastener is available. Other than this, the standard method is torque-angle and is the only method that I know of that can be utilized in volume production for tensioning fasteners accurately in blind holes. Comments....???

dkozloski
05-06-05, 04:38 PM
Bbob, there was an article published in Scientific American magazine several years ago submitted by an Australian engineer in which he stated that he had identified so many variables associated with tightening bolts with a torque wrench that the whole idea was an exercise in futility. In fact he stated an argument could be made that it was dangerous because it gave you an undeserved confidence. One of the more egregious examples I ran across was an engine where several of the connecting rod nuts were found to be torqued to the required value on the bolts but the bolt/nut combination could be twiddled in the rod because the nuts had galled to the bolt before clamping and some clown let them go out the door that way. The miracle was that they didn't break in 1700 hours of operation. Until something better comes along torque-to-angle is my choice.

mechanix
05-06-05, 04:48 PM
[QUOTE=bbobynski] I have personally watched techs ruin the threads in the block by "cleaning" them out with a cutting tap and ruin them by running a round wire brush into them with a drill motor to "clean" them. They are often ruined by not cleaning at all and galling old material into the aluminum threads with the new bolts. Of course, when this happens, the tech blames the crummy threads in the block...[QUOTE]

So...it's the mechanic's fault? I guess I "ruined" the threads in my block because I foolishly expected them to withstand the trauma of a tap. Shame on me. :hitstick:

BeelzeBob
05-06-05, 04:55 PM
Yea....my take on that type of thing was expressed above about the one type of testing for the antifreeze for combustion gases...."It is worse than useless....it is misleading". I use that statement a lot about different things. Using torque to tension fasteners is much like that, I agree. Torque can be worse than useless......it can definitely be misleading in MANY cases.


One one of the bike forums someone recommended anti-seize on spark plug threads. I got flamed, of course, for saying that this was not a good idea for a number of reasons....primarily because it changes the torque characteristics SO much that it is now very easy to overtighten and crack the plug and/or strip the threads in the aluminum head. The torque required to tension a bolt when antiseize is applies is cut in half in many cases.

I have seen several cases like you describe personally. Many years ago we were investigating a spate of intake gaskets leaking on a group of test car engines. The bolts were "torqued" correctly.....but...upon closer examination the heads of the bolts were about 1 mm from contacting the manifold boss. The holes in the prototype heads had been mis-machined too shallow and the bolts had bottomed out just as they came in contact with the manifold boss. Soooo close that it was not apparent at all visually but all the torque was going into bottoming the bolt....not stretching it or tensioning it.

This CANNOT happen with our torque-angle strategy. If a bolt bottomed the actual force required to turn it to angle would skyrocket and trip an alarm. All critical fasteners are tensioned with DC drive, electric spindle mulitples with two path feedback. There is a torque sensor in the shank of the tool and the current to the motor is measured and correlated to torque to cross check. For angle there is an angle transducer AND the armature rotations are counted as the DC motor runs the spindles to cross check the angle encoder. Even though the "angle" is the primary means always of tensioning the fastener arriving at that angle for that specific fastener will always generate a characteristic torque curve. Within a given range it is fairly repeatable (despite what I said about torque if the same joint is run down the same way all the time the torque should repeat fairly well for that specific operation) so the torque is always monitored during the angle part of the cycle and if it falls outside of the statistical limits established it sets off an alarm, backs the bolt all the way out and will not pass the engine down the assembly line. Bottomed bolts and untorqued fasteners are a thing of the past with equipment like this.

BeelzeBob
05-06-05, 05:01 PM
[QUOTE=bbobynski] I have personally watched techs ruin the threads in the block by "cleaning" them out with a cutting tap and ruin them by running a round wire brush into them with a drill motor to "clean" them. They are often ruined by not cleaning at all and galling old material into the aluminum threads with the new bolts. Of course, when this happens, the tech blames the crummy threads in the block...[QUOTE]

So...it's the mechanic's fault? I guess I "ruined" the threads in my block because I foolishly expected them to withstand the trauma of a tap. Shame on me. :hitstick:


Read the service manual. Don't use cutting taps on the head bolt threads in an aluminum block.

If it is not the mechanics fault then whose is it for not following the correct procedures...??? The 4.1/4.5/4.9 engines had a sticker on the throttle body extension and/or valve cover that stated, in effect, "this engine requires special assembly and service procedures as outlined in the service manual"....We even tried putting a sticker on it to warn mechanics to follow directions and they still didn't and laughed about the sticker. The information is out there but, you know the deal...."...you can't make him drink"

All the female threads in the heads and block are rolled...not cut. In effect, a rolling tap rolls into the hole and extrudes the aluminum. It doesn't cut the threads. The aluminum is actually extruded or forged in effect by the tap making the thread material very hard by work hardening it and by the improved desification of the extruding force generated on the aluminum. The rolled threads are 1.5 times stronger than cut threads in aluminum like that. They are also very a very "full" class of threads that provide a lot of engagement with the bolts. Running a typical cutting tap thru them removes material from the threads since most cutting taps are a much larger class of thread and , most critically, it removes the "skin" of the thread which is the strongest/hardest part of the thread due to the most work hardening.

It isn't so much the trauma of a tap but the fact that the tap you are using from the kit is the wrong thread form and the wrong type of tap. You do not expect generic bolts in the holes so why expect generic threads in the block.

It is a good practice to NEVER use a cutting tap on threads in an aluminum block. All engine companies that I know of use rolling taps in aluminum blocks and heads due to the superior strength of the thread form generated. This is not just a "Cadillac or Northstar thing"....it is industry wide. Lots to learn about aluminum engines.....

mechanix
05-06-05, 05:29 PM
You sound like the credit card companies who suddenly raise my interest rate to 30% because I missed a payment, then tell me "it's all there and clearly spelled out in the contract." *lol* Maybe it is, but who reads it? There is no sticker on my car and nothing that says you can't use taps in my manuals. I would expect threads to be sturdy enough to withstand a tap if they are going to hold head bolt torque. Remember that little aluminum V8 that GM was putting in the mid-size Oldsmobiles and Buicks in the sixties? I don't recall seeing any head bolt problems then. Northstars are not the only aluminum engines I've worked on. Tapped out a lot of aluminum threads in my day too, Bbob. Never seen nothing like this. A lot of great ideas in the N* engine. Unfortunately, head bolts aren't one of them.

gtm2u
05-06-05, 05:54 PM
gmt2u....back to this topic. There must be some confusion from what you saw and from what I said.

The head bolt size has not changed. I meant to elaborate on that last night but forgot about it. So...some of your conclusions here about what a "drastic change" might be indicating are a bit premature or erroneous.
...
Least everyone jump on the bandwagon of the coarse pitch fastener and think that it is a panacea understand that it creates it's own issues with a much greater propensity to loosen during thermal cycling...it requires a more aggressive loctite material to hold it in place. Also, since the thread pitch is more coarse the "angle" part of the fastening sequence becomes more stringent due to the greater percentage of stretch associated with each degree of rotation of the bolt.
...

Which brings me to something else stated earlier in one of your posts that needs clearing up. You mentioned that Cadillac was using the torque angle procedure which the fastener industry had abandoned long ago. I since verified and posted that the fastener industry was still "on that bandwagon" as you put it....and no retort from you...!!!
...
Other than this, the standard method is torque-angle and is the only method that I know of that can be utilized in volume production for tensioning fasteners accurately in blind holes. Comments....???

I hate typing in this tiny window for much gets lost in thought processes.

I don't think I was the source of the 12mm x 2.0 pitch for I thought someoone else had posted. If I am then I do know where it came from and it's with someone who Cadillac does business. It was in a phone conversation with what I thought was engineering staff.

While I accept your logic re pitch angle considerations the fact is others have been successful with bolts and studs. And in some cases no thread compound was used ("clean dry threads") and they did not work loose. Do consider that some had more strict scheduled retorque intervals.

My source for returning to the torque wrench method rather than torque angle comes from a major stud maker. Since I am not prepared to name those sources from a business relationship standpoint I am sure you also cannot reveal some of your sources. I've fought urban legends all my life and it would be out of character for me to have misrepresented anything I've written.

While thinking about this torque angle it came to mind that when using CNC machines that it may be it's easier to write logic condition A met, advance X degrees rather than a torque value in resistance encountered by the machine equipment. Somebody had to establish what the actual torque really was before they could then plot a graph which the CNC could understand. I doubt that it would be practical to do the math calculating ramp angles vs pitch etc. as an only source of establishing clamp force. I can see why this would be more efficient on the assembly line but back to my world of having a tactility to know when threads are bad and either repair the condition or add additional value overcoming the resistance. This is not the norm but it can happen and judgment calls have to be made.

I was trying to tie this together as a source for contributing to the problem as well as the aluminum.

Cheers,
GTM

dkozloski
05-06-05, 06:10 PM
Bbob, anti-seize on spark plugs was declared verboten in the aircraft industry after it was found that highly trained technicians were dunking the plugs in the anti-seize pot to apply it to the threads. Intelligence is finite and can be measured but there are no limits to stupidity. The norm for aircraft spark plugs is now plain engine oil for lube.

mechanix
05-06-05, 06:22 PM
Look, I don't expect you to look at this from the consumer's point of view because on this issue, you are in the engineer's camp. But please think about this issue the next time you buy a product that breaks, or goes bad shortly after purchase. If contacted, I'm quite sure that the manufacturer of that cheap, poor quality product will tell you that it's your fault because you abused it. Conversely, I realize that you engineers labored long and tirelessy to produce what you probably feel is some of your best work. And you don't take kindly to people bashing the fruits of your labor. Credit must be given where credit is due, and you are not getting much of that from the public. So allow me to go on record as being one of the few who say that the N* engine, indeed the Cadillac car, is one impressive piece of machinery! And I commend you and your colleagues on a job well done - one that I couldn't come close to doing myself.

But it is we mechanics who have to work with what y'all give us to work with. And sometimes it's a mess! *lol* Not all engineering milestones are great ones. I don't mind fixing them because that's how I made my living for most of my life. But the N* head bolts are an engineering faux pas that costs consumers a fortune to repair. It's no "easy fix" as you have stated, and it should not have happened. I think that those of us who have been "stung" with head bolt "venom" would like to see a little accountability on Cadillac's part. We sure DON'T want to hear that it's our fault because we abused the product. If the product won't withstand normal maintenance, then what good is it? I'm not talking about textbook, perfect adherence to maintenance schedules, I'm talking about the routine, normal maintenance that it is most likely going to get in the real world. If a product won't tolerate "industry standard" repair procedures, then what good is it? If it is so delicate that "special care" must be taken not to break it, then that should be made common knowledge - not a footnote buried somewhere in a 2,000 page manual or a sticker under the hood that blows off during the first engine cleaning.

If I sell you a car Bbob, and I fail to tell you that you must never accelerate over 50 mph or else the engine will blow up, who's fault is it when the failure occurs? Mine because I didn't tell you? Or yours because you didn't ask? 'Nuff said 'bout that.

dkozloski
05-06-05, 07:41 PM
Mechanix, I hate to be the one to tell you but your approach to being a mechanic is much like a seat of the pants bush pilot compared to a part 121 airline transport pilot. What separates the old time mechs from the new breed technicians is the acceptance of the fact of life that you can no longer rely on experience alone but instead you must have all the current information at your fingertips and posess an eagerness to use it. If you have the attitude that to read the book is to admit defeat you're in for some tough sledding. That being said I'm glad that I'm now retired so that I have plenty of time to sit back and preach to the current crop.

haymaker
05-06-05, 08:31 PM
I have two questions for any past or present Caddy tech. Have any of you installed a time-sert in an N* before the year 2000? Have any of you heard of the GM “Engine Exchange Program” during the ‘90’s?

BeelzeBob
05-06-05, 11:38 PM
If you want a reliable, repeatable, fail proof test use the 120 PSI shop air. Period. I have seen all the other tests fail for the reasons given. I have seen them test for a head gasket failure when there was none and I have seen an engine with a head gasket failure "pass" those tests. I have never seen the 120 PSI shop air test fail. If the cooling system doesn't bubble then the gasket is sound. If it bubbles...then there is a head gasket failure.

I would NOT recommend 2000 PSI. We use 2000 PSI nitrogen bottles regulated to a MAXIMUM of 700 PSI as I mentioned. You do not want to even test to that level of 700 PSI in the field.

First....combustion pressures are nowhere near 2000 PSI on normal engines. Even our supercharged engine that makes well over 100 HP/liter is at a little over 1400 PSI max cylinder pressure. I called it 1500 in an earlier post for ease of comuting and to illustrate worst case. 1400 PSI is about as high as you are going to see in any engine coming into a shop unless the guy is running a 300 HP NOS shot and he is probably knowing the head gaskets are bad. Sooo...forget 2000 PSI completely whether for leak checking or for illustrating cylinder pressure.

Combustion pressure of 1400 PSI is an extremely brief interval. The head gasket and sealing surfaces only see this pressure for milliseconds...not continuously. If you test a perfectly good head gasket and let it sit there at 750 for 10 minutes it will likely start to leak and you will deform the firering of the head gasket and possibly even blow it out in a section. There is a big difference in the joint seeing 1400 PSI for several milliseconds and sitting there for 15 minutes at 700 PSI.

That is why I recommend using 120 PSI or so for testing a "used" head gasket in the field. It is high enough to find any leak or weakness at all yet it has proven, even in cases where development head gaskets were known to start to fail, to not hurt the gasket further and demonstrate whether it was leak proof or not. Do not test with pressures of 120 PSI in the combustion chamber in the engine in the field. I cannot stress this enough. There is plenty of safety factor doing the test at 120 PSI to find a weak gasket and yet there is also plenty of cushion to not hurt anything or anybody.

Yes....you have to test every cylinder. It is tough doing a good job sometimes....LOL. The advantage, however, is that you know the exact cylinder(s) that are leaking based on which cylinders bubble. A quick and easy test, if you are not concerned too much with accuracy, is to sniff the surge tank/radiator or use the dye strips or liquid. If you are comfortable with those tests, fine. You'll never convence me to change MY head gasket with them, however. Probably the best compromise would be to sniff or dye strip it and if that test indicates a leak then do the cyliner pressure test to positively confirm.

I have seen more than one head gasket removed and the individual left scratching his head trying to figure out exactly which one was leaking.. This is very common on some of the pushrod engines, including the 4.1/4.5/4.9 family when the engine suddenly has coolant in the oil and the shop says...."headgasket". Fact is, 90% of the time, it is the intake gasket that was leaking. There was an individual that experienced this misdiagnosis by a shop on the caddyinfo forum about a month ago. With the pressure test he proved that the head gasket was fine and fixed the intake gaskets instead. Since the intake gaskets need to be replaced anyway with the head gasket the problem gets fixed but the individual is unable to see a problem with the head gaskets and pays WAY too much for the repair.

There is still a live thread in the Seville/Eldo section of an individual with a Northstar Eldo. Overheating. Dealer diagnosed as head gasket via sniffer. Individual did the combustion chamber pressure check per my recommendation and found the head gaskets to be fine. More diagnosis uncovered a plugged vapor vent line. A piece of wire up the hollow bolt at the water crossover fixed his "head gasket" problem. Another individual on this forum posted about 6 months ago from Hawaii with similar diagnosis. Pressure check showed head gaskets were fine. Found plugged vapor vent line from previous owner throtttle body heat bypass mod. Fixed with replumbing.

Trust me. This test works. If you need a text book I just wrote one...LOL. I have never seen it fail. Try it and prove me wrong. It is cheap to make the tools and really doesn't take much time, especially on a Northstar. I would probably allow an hour or so taking my time but I am slow and since your mechanical skills are far better than mine (per your own admission) you can certainly do it quicker. You wrote this, not me...LOL LOL LOL.


gmt2u....I realize that mechanics need to be accurate and such. Just like doctors need to be accurate and such. 3 of them tried to kill my wife with their misdiagnosis 3 years ago so I trust them about like I trust mechanics. Do your own evaluation of the test and see if it works for you. There is sound engineering experience and data behind it and it is used in engineering labs all over the world. I do not even know of a sniffer or dye check that is used in any of our garages or labs. They are too unreliable. Period. And we test parts to failure all the time and need to be absolutely certain.

BeelzeBob
05-06-05, 11:51 PM
Look, I don't expect you to look at this from the consumer's point of view because on this issue, you are in the engineer's camp. But please think about this issue the next time you buy a product that breaks, or goes bad shortly after purchase. If contacted, I'm quite sure that the manufacturer of that cheap, poor quality product will tell you that it's your fault because you abused it. Conversely, I realize that you engineers labored long and tirelessy to produce what you probably feel is some of your best work. And you don't take kindly to people bashing the fruits of your labor. Credit must be given where credit is due, and you are not getting much of that from the public. So allow me to go on record as being one of the few who say that the N* engine, indeed the Cadillac car, is one impressive piece of machinery! And I commend you and your colleagues on a job well done - one that I couldn't come close to doing myself.

But it is we mechanics who have to work with what y'all give us to work with. And sometimes it's a mess! *lol* Not all engineering milestones are great ones. I don't mind fixing them because that's how I made my living for most of my life. But the N* head bolts are an engineering faux pas that costs consumers a fortune to repair. It's no "easy fix" as you have stated, and it should not have happened. I think that those of us who have been "stung" with head bolt "venom" would like to see a little accountability on Cadillac's part. We sure DON'T want to hear that it's our fault because we abused the product. If the product won't withstand normal maintenance, then what good is it? I'm not talking about textbook, perfect adherence to maintenance schedules, I'm talking about the routine, normal maintenance that it is most likely going to get in the real world. If a product won't tolerate "industry standard" repair procedures, then what good is it? If it is so delicate that "special care" must be taken not to break it, then that should be made common knowledge - not a footnote buried somewhere in a 2,000 page manual or a sticker under the hood that blows off during the first engine cleaning.

If I sell you a car Bbob, and I fail to tell you that you must never accelerate over 50 mph or else the engine will blow up, who's fault is it when the failure occurs? Mine because I didn't tell you? Or yours because you didn't ask? 'Nuff said 'bout that.


BS.

I don't take kindly to critisism of the product I work on...!!!....NO $HIT. I could have told YOU that. LOL LOL

There is not a foot note buried in 2000 pages telling the customer on 1993/94/95 Northstars to change the coolant every 2-3 years/24-35K miles. It is clearly stated in the owners manual and the service manual. So they don't and gmtu2 buys the car and the head gasket fails becuase the core of the gasket is corroded away and the gasket has collapsed and he is beside himself trying to redesign the head bolts because someone didn't maintain the coolant.

How many people have posted on here about the dealer ship knowing NOTHING about the coolant supplement pellets in the 4.1/4.5/4.9 engines and there are notes in the service manual and A STICKER ON THE RADIATOR CRADLE and notes in the service manual. READ IT. If you think that that is buried or hidden you are nuts. The information is out there and available and it is up to you to learn how to repair the product. How many shops tear into the engine without even having the service manual to go by for notes and information. A tech in a garage posted on here about a year ago asking for "torques" so he could finish up a customers car. Jeeezzz.... He shoud be paying the customer for using his car for training.

By the way, I released the "stickers" for the service info on the 4.1/4.5/4.9. It will NOT blow off with a pressure washer. That was one of the specific requirements of the sticker on the engineering drawing. Neither will the stickers put on the cradle for emission information, fluid checks, coolant supplement requirements, etc. I have done the testing and know. Besides, I pressure wash the under hood of my own personal cars all the time and the stickers do not blow off so your comments are groundless.

I know that there are a hell of a lot of good and great techs out there but don't give me this "FU Engineering" crap when I have seen engines returned from the field with "incurable oil leaks from the rear main seal" when the problem was a power steering line leaking into the valley and running down the back of the block. The techs changed the rear main seal twice, gave up and replaced the engine. I see stuff this DUMB all the time from the field so the gate swings both ways pal. Both sides need to understand each other's point of view and I honestly see far more concern on the engineering side about service than from the other direction. If you can throw it over your sholder blindfolded and it will end up on the engine correctly you have a better than even chance of successful service in the field if the tech does not bother to read the information provided and learn about new products.

dkozloski
05-07-05, 12:10 AM
Bbob, the cad plating with a chromate wash protects the aluminum as well as the steel bolt. I would hope that it would prevent the intergranular corrosion of the aluminum that is reported as pulled threads that crumble. Intergranular corrosion is also the result of a bad heat treatment so maybe the variable cooling rates in a die casting are coming into play. You just never see these things in an aircraft engine.
I'm with you on the 120 psi with a sparkplug adapter. Observe the KISS principle. Trotting out the exotic test setup is good for impressing the flatlanders but the cost, time, reliability, benefits equation goes to the shop air adapter. I have tested tens of hundreds if not thousands of aircraft cylinders and observed tens of hundreds if not thousands more and was satisfied with the results every time. I even built an adapter to plug the cylinder at the base so I could pressurize the cylinder off the engine and submerge it to test the head-to-barrel screw joint.

BeelzeBob
05-07-05, 12:17 AM
My source for returning to the torque wrench method rather than torque angle comes from a major stud maker. Since I am not prepared to name those sources from a business relationship standpoint I am sure you also cannot reveal some of your sources. I've fought urban legends all my life and it would be out of character for me to have misrepresented anything I've written.

While thinking about this torque angle it came to mind that when using CNC machines that it may be it's easier to write logic condition A met, advance X degrees rather than a torque value in resistance encountered by the machine equipment. Somebody had to establish what the actual torque really was before they could then plot a graph which the CNC could understand. I doubt that it would be practical to do the math calculating ramp angles vs pitch etc. as an only source of establishing clamp force. I can see why this would be more efficient on the assembly line but back to my world of having a tactility to know when threads are bad and either repair the condition or add additional value overcoming the resistance. This is not the norm but it can happen and judgment calls have to be made.




The problems with relying on pure torque have been documented for ages in every text book and article about bolt tensioning written in the last 20 years. Even 20 years ago torque-angle was rapidly becoming the norm for critical fasteners so it is not something new nor unproven. Any fastener maker that relies on torque is a fastener maker I would personally not trust too far. ARP is very strict and to the point about the rod bolts that they sell that they must be tensioned by measuring the bolt stretch and NOT by simply torquing. ARP is one of the premier high performance fastener manufacturers around so I would tend to trust them. Using the torque-angle approach (with the properly developed specs) is far more accurate than simply torquing and is very close to being as good as actually measuring bolt stretch.


I outlined what was involved in developing the torque-angle specs in an earlier post. The Cliff Notes version is as follows. The fundamental start of the spec is to determine the minimal torque that will take all the lash out of the joint and make the joint zero clearance. That is often relatively easy by imperical testing. The fastener load vs. deflection curve is developed by simply pulling the fasteners in a TiniusOlson Machine and plotting the curve of load vs. deflection. Knowing the load desired in the joint is it easy to pick off the necessary deflection of the bolt desired and from that it is easy to calculate, via the pitch, just how many "degrees of angle" are required to stretch the bolt that far. From there, the fastener development engineer assembles joints with the preliminary specs and measures the load in the joint by characterizing bolts (measuring their specific load vs. deflection curves) and then measuring how far the bolts actually stretch using the torque-angle spec. If the joint if open this is easy as the bolt length is easy to measure. In blind holes, like the head bolts, the head bolts are characterized for length by measuring the length sonically with a StressMic or Raymond sonic measuring equipment. The bolts are tensioned with the proper torque-angle and then the length is remeasured sonicaly as the bolt is in place to see how far it stretched. Knowing the load curve of the bolt and the deflection or stretch the bolt load is relatively easy to determine. This sounds a lot more complicated than it is. A good tech can go thru all 20 head bolts and come away with complete bolt loads in about 2 hours of work. We do that work so that you don't have to. If you just use the torque-angle specs given then you will have the correct load. Period. If you change the load/stretch relationship with other bolts or studs or ???? then you are on your own. Period. I honestly do not know how to re-establish this relationship without the correct development tools like a Raymond sonic bolt length checker and a TiniusOlson machine.

Once per week an engine is sent down the production line with special, parrallel ground head bolts (for sonic length checks) and the bolts are measured before they are dropped into the bolt holes. The bolts are tensioned by the automation and the engine is sidelined long enough for the tech to remeasure the bolt lengths (stretched) so as to establish the load in the bolts. The whole complete goal in a bolted joint is to establish the correct bolt tension so this is an "audit" check in addition to the controls on the torque-angle procedure to ensure that the joint is tensioning correctly... So, in effect, we cross check the specs and the loads assumed once per week on production engines thus insuring that the specs are accurate, that the torque-angle specs are accurate and that the desired results are being achieved. I can walk you up to the assembly line and show you this history chart at that station. It is religiously maintained.

Torque-angle is unquestionably the way to go. Anyone who tries to convince you otherwise should be listened to with a large grain of salt. Very large grain of salt.

I have found that this correlates very well to people that have the correct "feel" for a bolted joint. A mechanic with this feel can tell when the bolt is taking up the slack and then can sense that the additional "angle" he is inducing is stretching the bolt. He can also tell that if the torque required to turn the bolt the desired amount starts to fall off that the joint is feeling "soft" and that that is an indication that the threads are failing. Despite my poor mechanical skills I find that I use this technique inherently and that the outlined, specified torque-angle procedures closely mimic real life tensioning of bolts by knowlegeable hands. I have more than once pulled a joint to the "correct" tension purely by feel on a bet only to have it verified as being within 10% of the instrumented desired value when measured with a Raymond Gage. Torque angle is the closest thing to real life and accounts for lubes and other variables very nicely. Certainly if a tech "feels" the joint softening..i.e..the required torque dropping off as angle is reached... then that is cause for alarm. That is why knowlegable techs are desireable. Without them, pure torque-angle is the next best thing. In the real world, for example, if the bolt bottoms, the "angle" cannot be achieved without snapping the bolt off. Better to snap it off than leave it bottomed and not tensioned as torquing can do.

BeelzeBob
05-07-05, 12:29 AM
I even built an adapter to plug the cylinder at the base so I could pressurize the cylinder off the engine and submerge it to test the head-to-barrel screw joint.


I do my two stroke engines this way also. I plug the ports, pressurize thru the spark plug port and dunk the whole thing in the laundry tub to check for case and seal leaks.

Short of that, pressurizing and spraying with soapy water works well too.



In fact, a version of this test is used to verify the sealing integrity of EVERY engine built in production. The engine is pressurized and then vaccuumed and a pressure decay and vaccum decay curve is measured to make sure all seals and gaskets are sealing. Only 2 PSI is used in this case but that is sufficient with air to find even the tiniest leaks. That equipement is common on many assembly and subassembly lines to leak check components.

BeelzeBob
05-07-05, 12:34 AM
I don't think I was the source of the 12mm x 2.0 pitch for I thought someoone else had posted. If I am then I do know where it came from and it's with someone who Cadillac does business. It was in a phone conversation with what I thought was engineering staff.




I don't mean to pin you on this but the only reference like this that I have seen was from your post earlier. I know that I know better and would not have said or written 12 mm unless it was a gross typo of which I am perfectly capable...LOL.

If someone that "Cadillac" does business with told you that then suspect what ever else they may have told you equally for they were very wrong.

Sorry to make a big deal out of this but it is a glaring error and was the basis for some rather negative comments about the engine that really weren't warranted.

mechanix
05-07-05, 02:01 AM
Mr. Kozloski, it sounds like you are making assumptions that are not in evidence. The fact is, I have spent untold hours pouring over these manuals because I know that the technology has changed a lot since I was wrenching at a GM dealership. That is also the reason I support this forum and read all the threads that I feel might teach me something. Your accusations are unfair and I take offense to being analogged as a rank amateur.

Mr. Bobinski, I don't appreciate reading about stupid mechanics any more than you appreciate reading about stupid engineers. I have tried to show respect and give credit where credit is due. If there were something in my manual about not using a tap, I would have seen it. There are no stickers under my hood that elude to that fact. I have seen no threads on tapping the block on here. I have done my research. It is not my fault. I realize you have about five arguments going at once here and are probably a little heated, so I will say nothing more on the matter.

I respect you gentlemen and your opinions. However you feel about me is none of my business. It doesn't bother me to concede a point if the argument is well founded. I have done so several times on here. Can we put our egos back on the shelf please?

dkozloski
05-07-05, 02:47 AM
Mechanix, I did not intend to imply that you are an amateur. Your statements implied that you should not be required to research out all the exceptions to "industry standard" procedures. By my book that is flying by the seat of your pants. Every time I worked on an engine I was required to research the engine logbooks, the manufacturers service bulletins, service instructions, service and overhaul manuals, and all FAA advisory circulars and FAA Airworthiness Directives. The library of research materials that an Airworthiness Inspector is required to have available at all times cost thousands of dollars and requires constant revision, by law. You just assumed as a matter of course that you were in a game where someone had set a trap for you that you were required to find. If the guy ahead of you had screwed up you were expected to find it. You were responsible for finding it. I suppose the difference was that If I missed something some one is dead. If you missed something it's a little embarassment. The time to take care of the research often times was more than the time for the work.
I don't think that you should be held to the same standard but it sure helps if you have the pride in your work to try to research all the nuances of a particular job before you start collecting a customers money in the guise of being an expert mechanic. After all, if you want the big bucks and the respect of your peers you earn it. I had more than one apprentice come to me and offer to work for nothing if he could just be in my shop to see how I did things, based on my reputation for attention to detail.

mechanix
05-07-05, 11:26 AM
OK, thank you for that, dkoz. It's easy to misinterpret things on here, and I am not the world's most articulate communicator. If I came across as a pompous ass then I can understand your taking issue with that. But that was the polar opposite of my intention. A man who proclaims to know it all needs to get out of the business because he is a danger to himself and others. I view today's automotive industry much like a novice because things have changed so much. Perhaps I am a little sensitive when someone slams mechanics because we have always been the "whipping boy" when things go wrong. I have always treated other people's cars as if they were my own, without exception. I love to learn and I have read those Helm manuals almost cover to cover. I have read them while eating, while watching TV, and even read them in bed. For someone to imply that I am too egotistical to do any research is simply absurd.

I love this forum and the free exchange of ideas and information. But when tempers flare and the name-calling, character assassination and swearing begin, it just takes all the fun out of it. To disagree and still remain respectful is sometimes difficult to do. And I certainly apologize if I have ever stepped on anyone's feelings for I try very hard not to do that. To borrow a quote from Rodney King, "Can't we all just get along?" LOL

BeelzeBob
05-07-05, 12:31 PM
mechanix....how can mechanics be blamed for all the problems when engineers are blamed for all the problems...???...LOL Just kidding, really.

I think people take a lot of what I say wrong because I tend to be very direct but most all of it is said somewhat tongue-in-cheek as typified by the frequent use of LOL.... Maybe I should clearify that I am laughing with you and not at you. hmm...maybe I should start using LWY and start a new internet acronym.

Besides, for whatever gtm2u thinks of YOU read what he thinks of ME in previous posts. LALT....Lets All Laugh Together.

Probably the misperception in the service literature is that it states to simply clean the head bolt threads with compressed air and/or "a soft brush". The fact that it is called out specifically was meant to draw attention to how to clean the threads....as opposed to how NOT to clean the threads. Cutting taps are definitely out in any case.

It is frustrating from an engineering standpoint to provide the service info and to engineer systems like the onboard diagnostics only to have the field complain that engineers never think of service... I often wonder why they thought that the onboard diagnostics systems were incorporated back beginning with the digital fuel injection systems in the early 80's...???

dkozloski
05-07-05, 12:39 PM
Mechanix, some of the stuff I saw mechanics try to get by with and some of the ignorance displayed was criminal. But I have also seen work that was so skillfully done that it virged on being artwork. It all depends on how much effort you are willing to put into honing your skills and how much mental discipline you have to never let your guard down. I agreee it's not realistic to expect every mechanic to know every nuance of every arcane procedure but by the same token it's not smart for the mech to try to get along on his instincts and experience alone. I also think that engineers sometimes specify procedures to follow simply to have an argument to fall back on for CYA purposes. The blame game.

BeelzeBob
05-07-05, 01:03 PM
Back to my post above after that interruption...

The thing that gets me going on this forum are the occasional reports of people being ripped off by mechanics and dealerships and then getting told that it is the engine's or car's fault.

Things like being charged $500 or $600 for a Northstar water pump and the charge being justified by "how hard that Northstar is to work on" and "that water pump is buried and the hardest one to change in the world". I have been told this to my face by a tech in a Cadillac dealership....LOL...THAT was a mistake on his part. The water pump is obviously one of the easiest to change in the world if you have done it yourself...and yes I have.

Things like being told that the Northstar engine is a "throwaway" and "unrepairable".....duh.... It is extremely repairable and, in fact, precious little needs to be done to it generally. The tech strips a head bolt for whatever reason, "fixes" it with a helicoil and it pulls again so the engine is "irrepairable". People get told this by a service writer and they take it as gospel as if it came down off the mountain. A simple reading of a service manual would explain otherwise to them but...why bother.

Things like mechanics refusing to work on one of the 4.1/4.5/4.9 engines as they are supposedly "irrepairable".....more duh....they are just different and a number of people on this forum and others have expressed surprise at how easy the engines were to work on after they decided to take on the job themselves. The mechanics just do not bother to learn how to do the job right.

These are not things that have happened once but things that have come up time and time again. Heck, some of the claims people make on this forum would easily be debunked if they spent 10 minutes with the search feature on this forum there is so much info here now.

Not to rant again, but, so you understand, I am about the only stable proponent of the car and engine providing insight on this forum so the defensive posture comes from "years of experience"....LOL LOL

mechanix
05-07-05, 02:25 PM
Point taken, gentlemen. Mechanics and the art thereof is a lot like religion, I've noticed. One tends to be overly-defensive when it is called into question. *lol* And I guess mechanics in general tend to be stereotyped until proven otherwise. I still make mistakes and learn something new on every job I do. We all do. I've had to eat enough "comeback" work in my lifetime to support a family of five for a year! *lol*

I guess I must have a different manual than y'all have. Just to be sure, I re-checked and there is nothing in there about using or not using a tap. Under "Thread Repair Procedure," it simply lists the insert #s and the tap and drill sizes for their respective holes. I can find nothing in there about cleaning out holes...where to obtain inserts...or anything else about head bolt or main bolt holes. In fact, it doesn't even cover block inspection. It starts with the crankshaft and assembly begins from that point.

Of all the various shop owners I've worked for, I can honesty say that only one was actually out to make money and screw the customer. Most of the so-called "rip-offs" were due to mistakes and lack of experience. In any dealership service department, most of the technicians are under 30 years of age. I don't know about you, but I was still making a lot of mistakes and eating a lot of comebacks when I was 25! *lol* There, I think, is where the service industry gets it's stigma. Add to that service writers and service managers who have never wrenched for a living, and it's no small wonder that public opinion of mechanics is in the dirt.

gtm2u
05-07-05, 03:45 PM
...
ARP is one of the premier high performance fastener manufacturers around so I would tend to trust them. Using the torque-angle approach (with the properly developed specs) is far more accurate than simply torquing and is very close to being as good as actually measuring bolt stretch.
...

Torque-angle is unquestionably the way to go. Anyone who tries to convince you otherwise should be listened to with a large grain of salt. Very large grain of salt.

I have found that this correlates very well to people that have the correct "feel" for a bolted joint. A mechanic with this feel can tell when the bolt is taking up the slack and then can sense that the additional "angle" he is inducing is stretching the bolt. He can also tell that if the torque required to turn the bolt the desired amount starts to fall off that the joint is feeling "soft" and that that is an indication that the threads are failing. Despite my poor mechanical skills I find that I use this technique inherently and that the outlined, specified torque-angle procedures closely mimic real life tensioning of bolts by knowlegeable hands. I have more than once pulled a joint to the "correct" tension purely by feel on a bet only to have it verified as being within 10% of the instrumented desired value when measured with a Raymond Gage. Torque angle is the closest thing to real life and accounts for lubes and other variables very nicely. Certainly if a tech "feels" the joint softening..i.e..the required torque dropping off as angle is reached... then that is cause for alarm. That is why knowlegable techs are desireable. Without them, pure torque-angle is the next best thing. In the real world, for example, if the bolt bottoms, the "angle" cannot be achieved without snapping the bolt off. Better to snap it off than leave it bottomed and not tensioned as torquing can do.

I'm not trying to bloody anyone's nose with this block check procedure. I just spent almost an hour with Google and found no credible source supporting the 120psi procedure. However I did find NIASE and their board of governors support the 3 procedures I had listed. I have not searched SAE's site yet and invite anyone to do so or any other recognized authority.

It is important to me to not spread misinformation for it reflects on my credibility with my customers, my peers, and students. Your opinion is well presented along with mounted logic but I'm not about to jump on that steed except back to the shade tree. Said in the spirit of good humor PLEASE. It is an opinion and you have every right to have one, it just seems to be very much in the minority.

I also don't buy into bubbles in the cooling system as certain evidence either for I've seen enough weak water pump seals to know they can cavitate and draw in air when the cooling system pressure is low or open. I've been burned with that one more than once, also with mfgs trend to mount heater cores as the highest point it too is a source for trapped air which can get washed into the system when pressure is released and the rpm increased in short bursts.
.........................

I know who ARP is and what they have _published_ :)
.....................

It is a surprise to read what duplicates my own experiences in finding I can get that magic 10% torque value on many occasions and is almost never exceed given specs. I can also duplicate this with old long time friend air tools especially for staged head bolt and manifold torque. This is nothing I endorse for novice or average mechanics and rarely mention it. I also know that I can torque 15lbs with 1 hand and 25lbs with 2 using a 6" ratchet. I am less comfortable with auto trans valve bodies unless using a 1/4" drive.
................

I do wire brush threads to clean them and also know the difference of taking metal off the threads and removing grunge. (technical term eh) And I also use tap and dies for same with hand only, nothing I'm going to endorse and have been known to jump someone's bones if I hear the motor slowing down. I use a pick to remove aluminum that may have galled and torn out with bolt threads and there was a time when twisting wrenches and boat build that I had 7 rows of calouses on my palms.
...............
Interesting your experience with Doctors for I use them also as a measure for come-back ratios where I calculate .01% to .001% for my own work and I don't know a doctor alive that can make that claim.
......................

Mechanix, for what it's worth I have seen the special thread sticker notice on my Quad-4 Pontiac and the STS, they are also in the manuals and the 5 CD set which covers the Northstar. Yet I can't tell you if they have vacuum routing stickers required by law.
....................

Now I have a question for anyone about the 8mm 1.25 threads, which bolts or studs are special??

I just bought what appears to be the needed Kent Moore kit from eBay.

Item number 4379942236
Previous listing has more info on missing tools 4377723309

The last N* tool kit on eBay was the head bolt only and it went for $189 so I don't think I got hurt with this 3 kit purchase. I have a variety of 8mm 1.25 taps but if these are special then I'll have to replace them.

Cheers,
GTM2u

gtm2u
05-07-05, 05:20 PM
...
Of all the various shop owners I've worked for, I can honesty say that only one was actually out to make money and screw the customer. Most of the so-called "rip-offs" were due to mistakes and lack of experience. In any dealership service department, most of the technicians are under 30 years of age. I don't know about you, but I was still making a lot of mistakes and eating a lot of comebacks when I was 25! *lol* There, I think, is where the service industry gets it's stigma. Add to that service writers and service managers who have never wrenched for a living, and it's no small wonder that public opinion of mechanics is in the dirt.

I've been fortunate and discerning where I worked, you pay your money and you get your thing. I have known and fired those who were intent on fraud, this business has too many bad apples which cause public opinion to be less than stellar. Calif is by no means exempt from these cases especially in some of the well traveled routes such as LA to SF or Las Vegas. I switched vocation for avocation at 24-25 and was in the industry for 10 years when I started identifying myself not as a "mechanic" but as a "professional mechanic". You can find a lot of mechanics in the industry that only stay for a few years and just don't have what it takes. Lets face it many are self made and self appointed experts with few innate skills and have no desire to learn squat much less read technical books. They couldn't tell you the difference between a grade 2 over a grade 8 bolt. They couldn't tell you the alloy by looking at sparks on a grinding wheel much less how to sharpen a drill bit for aluminum or steel.

However if it's any consolation it really is not the highest complaint oriented business in the US for that falls on the carpet installing and cleaning business.

I've worked for service manager and with service advisors some with and some without mechanic skills. The best of them were without for they would not try to impress the customer with their knowledge, they would not stick their foot in their mouth and would only translate what the mechanic told them. If the customer had questions then the mechanic could be summoned for detail or invite the customer to come and inspect. I remember one service advisor who would lay on the BS so thick that he would burry the mechanic and the shop because he had worked on a few cars and m'cyls thus thought he was an expert. It is possible as I am an example of having a vast amount of knowledge and yet know the difference of when to hold the customer's hand and when to let the mechanic have those honors.

In my youth I applied to a large pharmaceutical co. for a sales job which required visiting doctors. I didn't get the job and when asked why I was told I had too many courses in the sciences and their experience was this would cause problems when sales staff would make unsupported claims and misrepresent the product. So I learned an important lesson when dealing with people that the mechanic is the expert, the service advisor is the translator, and service manager is problem resolution.

Cheers,
GTM2u

dkozloski
05-07-05, 05:52 PM
GTM2u, I noticed a reference to students that you made. I used to teach an aircraft mechanics course at a junior college to experienced military mechanics who wanted their civilian ticket. That was an environment where I felt like I was in a shooting gallery. Every statement I made was called into question and I welcomed this attitude because I always answered a question with a question to try to foster individual research. One procedure I encouraged was for a mechanic attempting something he had never done before to perform simulations in his mind. To try to visualize every step and identify pitfalls and responses before they happened. The very best people I am acquainted with do this as a matter of course even with the tasks they have done many times. I also tried to stress the importance of having your brain engaged even for the most mundane jobs like noticing when the simple wire brush you are using is doing damage. It doesn't take long at the job of instructor to realize how much it improves yourself.
Something else I have noticed is the way manuals for German equipment are written. They assume you wouldn't even be fooling with the machine unless you were already a well trained mechanic. The books explain the divergences from standard metods and assume you know all the rest already. They make no attempt to lead the DIYer through the minefield. This comes from their structured apprentice training programs that have a standard curriculum that they all follow. This is also why you don't see too many of them doing crazy things behind the wheel because they all received the same driver training.

BeelzeBob
05-07-05, 11:26 PM
gmt2u...I think you may misunderstand the head gasket check I described.

The test that we use...under varying pressures from 750 PSI nitrogen in the lab to 120 PSI shop air in the car would pressurize the combustion chamber and use any bubbles coming thru the cooling system under that condition as evidence of a head gasket leak.

I have often mentioned to people that they can fill the cooling system and start the engine cold and watch for bubbles from compression entering the system (which is what you seem to allude to with the reference of bubbles and revving the engine and air trapped in the system causing a false reading). I agree that that "test" is poor at best and not something to rely on. There are cases where the system will just erupt with "false boiling" that is a pretty sure indication of a head gasket failure but just watching for bubbles with the engine running is not what I am advocating.

The bubbles I mention are strictly when pressurizing the chamber with 120 PSI shop air. If you pressurize the chamber for 5 minutes and a steady stream of bubbles come thru the system to the radiator or surge tank you can bet your last dollar that the head gasket is leaking.

Just becuase there are no internet references to that test doesn't mean that it won't work , doesn't work or is something to suspect. Is this like "I read it on the internet so it must be true" but "I couldn't find it on the internet so it must not exist" ..... ???? You really need to talk to people that develop gaskets and sealing systems and ask THEM how they do the development testing. Not the local sales rep for the gasket company but the guys in the lab that developed the gaskets. I have worked with several different companies doing just that and I can assure you that the pressurization of the combustion chamber to simulate combustion pressure (albeit at a lower pressure to offset the continous pressure vs. a higher instantaneous pressure) is an industry standard way of quantifying head gasket sealing. The tests you mention are not. They might be the "industry standard" for the people selling the test equipment and I am sure that they have plenty of internet references to "their" tests but I don't believe them because I have seen them fail.


There is another test that often works that is a bit easier for the less equiped shade tree. Get a cooling system pressure tester, put it on the pressure cap fitting when the engine is cold and the cooling system is full and pump it up to 15 PSI and let it sit. Pull the plugs while you wait. Keep the system pumped up to 15 PSI if it drops. Don't worry about a pressure decay or anything...just keep the system pressure up. Leave it that way for 2 hours. Hit the key with the spark plugs out and watch the plug ports for coolant. It helps to put rags over the ports, etc. but you get the idea. This is very conclusive that a head gasket has failed if coolant makes its way into the chamber.

The problem with head gasket failures is that the failure mechanism and how it manifests itself is very hard to predict. Some head gasket failures will leak coolant into the cylinder when the engine is shut down cuasing misfire and steam (and sometimes a hydrostatic lock) and yet the engine will not overheat or have any other signs. Growe3 on this forum had such a failure. It was the head gasket but no combustion leakage into the cooling system so it would never have shown up on one of the tests you described. It showed up on the pressurized combustion chamber and the test where you pressurize the cooling system and wait and check the chambers for coolant.

Some head gasket failures will pressurize the cooling system and others won't. Some leak coolant into the chamber when the engine is running and others only when the car is shut down and the cooling system pressure stays up for awhile. It all depends on the head gasket, it's construction, how it fails, the size of the orifice that is the leak path, etc. If the leak path is very tiny combustion pressure will be held fine but coolant will still seep thru when under pressure the other way.

The air pressure check in the combustion chamber will always catch any head gasket leak that I have come across yet.



BTW...a small bone to pick... You call me "just another internet jock" yet you depend on the internet to research and disprove the test that I have learned via the school of hard knocks and 33 years of experience in the auto industry...???....hmmm....

dkozloski
05-08-05, 12:59 AM
Bbob, I have a small bone to pick with you. You made mention of the old saying about leading a horse to water but you can't make him drink. Here in Alaska we say that three Texans can. Two to hold his head under water and the other one to suck on his A--.

gtm2u
05-08-05, 01:07 AM
GTM2u, I noticed a reference to students that you made. I used to teach an aircraft mechanics course at a junior college to experienced military mechanics who wanted their civilian ticket. That was an environment where I felt like I was in a shooting gallery. Every statement I made was called into question and I welcomed this attitude because I always answered a question with a question to try to foster individual research. One procedure I encouraged was for a mechanic attempting something he had never done before to perform simulations in his mind. To try to visualize every step and identify pitfalls and responses before they happened. The very best people I am acquainted with do this as a matter of course even with the tasks they have done many times. I also tried to stress the importance of having your brain engaged even for the most mundane jobs like noticing when the simple wire brush you are using is doing damage. It doesn't take long at the job of instructor to realize how much it improves yourself.
Something else I have noticed is the way manuals for German equipment are written. They assume you wouldn't even be fooling with the machine unless you were already a well trained mechanic. The books explain the divergences from standard metods and assume you know all the rest already. They make no attempt to lead the DIYer through the minefield. This comes from their structured apprentice training programs that have a standard curriculum that they all follow. This is also why you don't see too many of them doing crazy things behind the wheel because they all received the same driver training.

Mine were high school seniors in a special honors class sponsored by Shell, Mobile, and Standard with a $3 mil annual budget so we had every thing you could imagine. Students were aptitude tested, had to demonstrate basic mechanical skills and interviewed in their junior year. All the selection was done by the oil companies thus I had the best of the best for they all wanted to be there, no attitudes, disruptive behavior, and hung on every word. I inherited the job for a year while the contract teacher was on sabatical. Needless to say not enough money but thoroughly enjoyable experience.
.....................

Yes, this is true also about Italian cars as well. When was the last tool kit included with an American car ... Model T? Those technical editors that write the manuals must be from another planet. Half of them are not laid out in a natural sequence of performing a task. And electrical component schematics are almost non existant for the seem to think no one can read them. The bulb check and warning system has to be the most complicated component besides the ECU on most cars yet to diagnose a problem they have next to nothing, not even pinouts. The DIY crowd are constantly trying to add amplifiers, radios, CD players, or alarms and invariably tap into these circuits and then wonder why their car doesn't start.

Cheers,
GTM

dkozloski
05-08-05, 01:51 AM
GTM2u, my teaching deal was a little different in that it was from 6-10PM and the students had to be up and on the job by 5:00AM every morning. They were a dedicated bunch. I got $72/hr. so I was expected to produce. The graduation rate was almost 100%. One student failed his piss test and was bounced clear out of the military.

gtm2u
05-08-05, 02:08 AM
gmt2u...I think you may misunderstand the head gasket check I described.
...

Just becuase there are no internet references to that test doesn't mean that it won't work , doesn't work or is something to suspect. Is this like "I read it on the internet so it must be true" but "I couldn't find it on the internet so it must not exist" ..... ????

You really need to talk to people that develop gaskets and sealing systems and ask THEM how they do the development testing. Not the local sales rep for the gasket company but the guys in the lab that developed the gaskets. I have worked with several different companies doing just that and I can assure you that the pressurization of the combustion chamber to simulate combustion pressure (albeit at a lower pressure to offset the continous pressure vs. a higher instantaneous pressure) is an industry standard way of quantifying head gasket sealing. The tests you mention are not.

. Hit the key with the spark plugs out and watch the plug ports for coolant. It helps to put rags over the ports, etc. but you get the idea. This is very conclusive that a head gasket has failed if coolant makes its way into the chamber.
...

The air pressure check in the combustion chamber will always catch any head gasket leak that I have come across yet.
...

BTW...a small bone to pick... You call me "just another internet jock" yet you depend on the internet to research and disprove the test that I have learned via the school of hard knocks and 33 years of experience in the auto industry...???....hmmm....

Argh, I'm going to conclude my participation with the 20,000-30,000 cars I've worked on in my life time and the way I have made a living most of my life is a whole lot more real world than what you do in the lab. I started twisting wrenches for a living in '65. If I were such a bumbling idiot I wouldn't have lasted. The problem with you is you can't accept what anyone tells you, this is the problem with so many engineers. Show me the manual, show me anything but your words. Walk into any Caddy dealership and ask the guys that work on the line. Your pressure pump also is not always valid for carbs, intake manifolds, throttle bodies also have water passages which can leak and drawn into the cylr.

You think I have not tried compressed air in the cylr, probably 30+ years ago and found it to be unreliable and that's the name of that tune.

Take your argument up with NIASE and SAE, publish your paper I for one need a good laugh. Get me a phone and a person's name for a gasket co and I'll call, that way you can continue to deny for I must not be telling the truth. I was hoping we had got past that page but I see we haven't.
.....................

Now if you want to do some thing for me tell me the aluminum strength and look at my ebay tool purchases and tell me if the missing tools have anything to do with blown head gaskets? That was 3 posts back. Whether I decide to use studs or bolts I would be a fool to not have a back up plan of attack which includes tools.

Cheers,
GTM

dkozloski
05-08-05, 02:53 AM
gtm2u, my experience with compressed air in the cylinder is just the opposite of yours. I tried it 50 years ago and it has been working great for me ever since. Somehow you have come to the conclusion that you have the only valid experience worth knowing. I found many years ago that there is something to be learned from everyone. I have some automobile repair manuals that go back to the 1930's that describe the procedure in great detail. Surly you are familiar with Audel's. How you can think that because someone can do with a simple setup a job that requires you to have something more elaborate to do the same thing somehow makes them an unreasonable incompetent fool is not logical. You have a very Germanic attitude; why use a simple solution when a complicated one will do the job? Maybe your problem is that using compressed air to test the cylinder for leaks requires analytical thought.

gtm2u
05-08-05, 04:38 AM
...
Somehow you have come to the conclusion that you have the only valid experience worth knowing.
...


This is nonsense, shoot the messenger. I gave you citation and still an argument. You and bbob write a paper, submit it to any recognized publication and see if it gets published. We had cast iron engines with copper head gaskets back in the 30's, we now run 10:1 compression, composition gaskets, computer designed heads, and think your way is the only way. I report my experience as a Master Mechanic, I report with citation industry standards and you want to take _me_ to task and not the authorities. We use to have band brakes, we switched to drum and then to disks because it's called progress and reliability.

Frankly I don't care how you check for a blown head gasket, I do care that the person who asked the question be given information which is recognized as industry standards.

What the hell is the matter with you people, you bored, got closet fever, smoking some funny weed, or bent elbow. Neither of you have proved anything, it's you charge to support with valid current information. I'll tell you just what I said to bbob this is my last.

Cheers,
GTM2u

dkozloski
05-08-05, 02:11 PM
gtm2u, I prefer to give someone information that they can implement with a minimum investment that will give them the results they need at least 99% of the time. An escoteric procedure requiring a capitol investment and training beyond the scope of your average DIYer is not practial advice. It may remove some ambiguity somewhere out there in that questionable 1% area but when that problem arises is the time to pursue that. The average guy with the average case is going to shoot air into a cylinder and see coolant and bubbles come out the filler neck in the highest percentage of cases. That tells him all he needs to know. Granted, there are smaller, harder to detect leaks that will require more stringent measures but we have already eliminated the largest share of these out under the shade tree. You need to get out of the direct sun and get over here with us. Why use a complicated procedure when a simple one will do the job? Why run the bill up with expensive redundant tests like the doctors do? Wait until you have gone through the simple test especially since the possibility of a false positive is nil.

ktills45
05-08-05, 03:30 PM
gtm2u, I prefer to give someone information that they can implement with a minimum investment that will give them the results they need at least 99% of the time. An escoteric procedure requiring a capitol investment and training beyond the scope of your average DIYer is not practial advice. It may remove some ambiguity somewhere out there in that questionable 1% area but when that problem arises is the time to pursue that. The average guy with the average case is going to shoot air into a cylinder and see coolant and bubbles come out the filler neck in the highest percentage of cases. That tells him all he needs to know. Granted, there are smaller, harder to detect leaks that will require more stringent measures but we have already eliminated the largest share of these out under the shade tree. You need to get out of the direct sun and get over here with us. Why use a complicated procedure when a simple one will do the job? Why run the bill up with expensive redundant tests like the doctors do? Wait until you have gone through the simple test especially since the possibility of a false positive is nil.

Amen. ;)

dkozloski
05-08-05, 05:43 PM
One point I didn't mention earlier is that contrary to other methods the compressed air procedure pinpoints the faulty cylinder or cylinders. Now the owner has the option of repairing only the faulty head, especially if it means the engine won't have to be removed. Another money saver. With a little asking around I found out that for $25 Harvey DIYer can make his own adapter, rent an air compressor for a couple of hours, do his own testing , and have money enough left to buy beer to cushion the blow of the results. What more could you want. It's a no-brainer.

gtm2u
05-08-05, 06:22 PM
gtm2u, I prefer to give someone information that they can implement with a minimum investment that will give them the results they need at least 99% of the time.
...
An escoteric procedure requiring a capitol investment and training beyond the scope of your average DIYer is not practial advice.
...


I completely agree with the 1st and a qualified endorsment of the 2nd.

I stated:
the chemical block check (I question if you people know what I'm talking about) may or may not be free from the dealer or independent shop. (It was free at the dealership where I last worked.)

I stated:
the "kit" can be rented or purchased from many of the chain auto parts stores. NAPA sells the kit for $46, so the rental can't be that expensive. Cost of fluid a DIY lifetime supply is $8.
.............

With a little bit of knowledge you could make the hardware for less than $10 including the gasoline to drive to the hardware store and a tropical fish store for an air stone.
........................

The chemical solution (phenophalene & water?) is non toxic, not hazardous and is completely reversable. My 8oz bottle lasted over 20 years as a professional mechanic because I purged air and reversed the reaction.
........................

In summation a phone call to a shop could get the test for FREE performed by a mechanic. DIY block check rental costs less than $46, make your own tool $18, or ownership $46. There is no "training", test takes 5-10 minutes.
Ain't no esoteric about it, an 8 year old kid could perform the test and report results.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Compare the costs of a compressor, fittings, air hose, spark plug adapter made or purchased from Snap On.

......................

Now we have a _very_ serious hazard to life and limb for the DIY or even professional mechanic who is not familiar with the process which has not been mentioned at all. I saw a mechanic loose the first and second joints of 2 fingers when he put 120psi to a cylinder because he left the key on and had not established TDC or BDC and the engine started. He could no longer hold a hammer to remove brake drums for it would fly out of his hand. He lost his job and his livelyhood as a mechanic, how esoteric is that...

I've had an engine rotate on me twice, the first time was I didn't know and the second time was a burned intake valve that allowed air to escape from 1 cylr and into another. I learned to prop the throttle open after that.
.......................

Now I want to see how smart you people are and let someone write a job description on how a DIY can _safely_ perform this test (could include a leak down also). If taken to a shop they will charge at least an hour labor and probably not on a customer wait. This is also well beyond the scope of an 8 year old kid. Hopefull we won't have amatures passing out their blessings as if they knew something I don't.

Cheers,
GTM2u

dkozloski
05-08-05, 06:59 PM
Bbob has already described the procedure of removing spark plugs, putting a stick down the hole, carefully turning the engine to TDC and applying air. It seemed pretty clear to me. If you remove all the plugs to begin with the engine is easily positioned and the odds of inducing an unwanted rotation are pretty slim and of course won't run. I bet a high percentage of DIYers already own a compressor. Plus the added benefit of pinpointing the failed cylinder/cylinders. How do you plan to do that with your block check kit? How do you explain away a false positive?

BeelzeBob
05-09-05, 12:18 AM
You know, gmt2u...I have honestly tired to share information with you. My posts are about 90% technical content and description and that is it. I posted the information and the background and explainations so that it would be understandable by anyone reading it, not just you.

Your posts continue to be a lecture about what you know and how you do it and how experienced and great you with about 10% technical information. You seem to miss the point on the last post by bringing up the test of the bubbles when the engine was running.

I am not sure what set you off in my last post, there. I tried to clearify the test I have commonly used very very successfully as it was obvious from your previous post ,when you spoke about "not trusting the bubbles with the engine running as air can get into the cooling system, etc", that you misunderstood something. If you look back you will find that NO ONE had mentioned looking for bubbles with the engine running until you made that statement so it is unclear to me why you made it and less unclear why you then went on to unload more crap at me because of it.

I find it appalling, quite frankly, that a man of your suppossed experience cannot understand how a test like that could be run very successfully. If you think that it will not work, don't waste my time telling me it is not "published" or there is no reference on google for it. I could care less. Explain to me in common engineering logic how that test would NOT work or how it could be misinterpreted if done correctly. Then we can discuss what may be right or wrong about it. But spouting about how it is not "published" and such so it must be wrong is a waste of everyone's time.

I work every day in an arena where few things that we are doing have been published. We basically write the book on every project we do because it exceeds the prior art by a significant margin. I am quite used to writing setup and test procedures that MUST BE INVENTED because no one has done then yet. I wonder who wrote the throttle body minimum air rate and TPS and idle speed control motor setup instructions when the first TBI system was put into production.....hhhmmmm.....no prior art to search on the internet for that. Same with many procedures and tests that are in our service manuals today. My concern is DOES IT WORK..??? Not, has someone done this before so I can be sure it works right. When we set out to make the Northstar engine capable of running on lower cylinder counts when low on coolant and overheating so as to protect itself do you think we went to the internet to search on google to see if it would work.....hahaha.

Please, from your experience, explain to me how, if air pressure is put into the combustion chamber and the cooling system starts to bubble a steady stream of bubbles, how this could be ANYTHING other than a head gasket leaking....it is infallible. Similarily, if there are not bubbles after 5 minutes or so, explain to me how a failed head gasket could be holding 120 PSI air pressure. It cannot do it. No matter how tiny the leak. THIS is the type of logic and information I would like to hear from someone wise and experienced....not a snide remarks about who endorses the test...


Since when does it require much of a capital investment to take and old spark plug shell (free) and tap it with a 1/8 tap (laying around the garage or $5 at Sears) and put it a 1/8 pipe nipple ($.99 at Home Depot if it is not laying around the garage) and hook it to compressed air?? Really now..?? Most anyone on here that is contemplating doing any work on their car has an air compressor so that is really not an issue. This test is very inexpensive. Compared to buying a sniffer like you recommend it is dirt cheap. The fact is that many folks on here have used that test and confirmed to me that it worked excellently. As far as difficult for a DIY, if they cannot screw a spark plug adapter into the hole and put air to it then they are NOT likely going to be successful changing the head gaskets. It is so simle as to be elementary for most anyone.

Yes, I am aware that it can cause the engine to turn over. That is why the instuctions that I give to people always indicate to put the piston at TDC. This is pretty simple, you take the plugs out, drop a wooden dowel down the plug hole (we are talking about Northstars here, right, so you can do this VERY easily), turn the engine over manually until the dowel stops rising and you are close enough to TDC for that test. That is neither complicated, expensive nor dangerous...and it only takes 60 seconds if you are slow.

Your horror story is BS. First, why would any mechanic be digging into the engine with the battery connected (something has to run the electrics for the engine to "start" when rotated). Secondly, if you remove all the spark plugs as most people would do running this test the engine cannot "start" with the plugs out. At worst, it will turn 1/2 revolution. Not something to be toyed with but not exatly life threatening to me. People will always discover ways to hurt themselves working on engines. Done correctly, the air pressure in the cylinders is not likely to contribute to the harm of anyone. Any mechanic that dives under the hood with the battery still connected and the key on is an accident waiting to happen for a variety of potential causes. The air pressure into the cylinder did not hurt him, his own stupidity did.

I will bet my last dollar and put the pressurized air test up against anything you have mentioned for accuracy, repeatability and it's ability to find the tiniest of leaks. It will find things that your suggestions will miss all day. I have seen it happen.

Please, explain to me how this test is so "complicated" when anyone that is half a shade tree mechanic can make up the fitting for free and run the test without buying any special tools or solutions or anything. They can do it at home at their convenience and get a positive answer on whether the head gaskets are good or not. You go to great lengths to stretch logic to maintain your pride and not admit that someone might know something that you don't.



I figure at this point, from trying to openly discuss things with you that it is going to be very difficult with someone who is obviously such a legend in his own mind to get thru to you. With that chip on your shoulder you'll never accept or admit that anthing I propose to you would work anyway, so I am obviously wasting my time with you. BTW....I wondered who you were or what you might look like so I looked up POMPOUS in the dictionary...and...sure enough....they had your picture right there. If you don't understand this, go back and read all your posts and soak in the condescending BS you have posted time after time.

Use the tensile strength of aluminum from the engineering handbooks you use to prop the door open with. That is as good an information source as any. It is not going to be perfectly accurate for diecast aluminum deep in the block, not, but, without sectioning a block and cutting a test sample from the area you are concerned about, no one knows the specific data you request. You wouldn't believe me if I told you what is was anyway...??? Besides, I am not your lacky to look up the information for you and to look up your e-bay purchases and tell you if they are correct. Do it yourself. As for your homework assignment to write a procedure....does the phrase "pound sand...." mean anything to you...???

gtm2u...I really don't want you to go away mad....I just want you to go away. Period.

dkozloski
05-09-05, 12:59 AM
Hey Bbob, that's me you quoted. I'm on your side on this one.

BeelzeBob
05-09-05, 01:29 AM
Yea, thanks, I appreciate the support.

peteski
05-09-05, 01:45 AM
I have been following this thread so far, but it is getting really silly.

Both you, gtm2u and Bbob are not spring chickens or cocky 20-somethings! You have life experience ahd should have enough smarts to see when a useful conversation turns into a pissing contest.

Gtm2u: you have a big chip on your shoulder - you thing that you are God's gift to mechanics and you also seem to have a strong dislike for design engineers (namely Bbob).

You seem to disagree with most of what he says. And he's been extremely valuable asset to this forum while you really haven't .

Just because you've been a grease monkey since the 60s, you aren't God!

Sorry but from the track record of Bbob and you, I have to say that I'll take his word over yours any day! But I don't blindly follow anything he says either. I apply "my" logic to whatever he says and I use only what I find useful and logical.
But I don't want to constantly question or disagree with him either.

And personally, I don't like your attitude!

Peteski

delzy
05-09-05, 02:42 AM
GTM2U, just pick up your marbles and go home!

mcowden
05-09-05, 10:22 AM
I have been following this thread so far, but it is getting really silly.

Both you, gtm2u and Bbob are not spring chickens or cocky 20-somethings! You have life experience ahd should have enough smarts to see when a useful conversation turns into a pissing contest.

Gtm2u: you have a big chip on your shoulder - you thing that you are God's gift to mechanics and you also seem to have a strong dislike for design engineers (namely Bbob).

You seem to disagree with most of what he says. And he's been extremely valuable asset to this forum while you really haven't .

Just because you've been a grease monkey since the 60s, you aren't God!

Sorry but from the track record of Bbob and you, I have to say that I'll take his word over yours any day! But I don't blindly follow anything he says either. I apply "my" logic to whatever he says and I use only what I find useful and logical.
But I don't want to constantly question or disagree with him either.

And personally, I don't like your attitude!

Peteski


AMEN! GTM2U, you said you were going to quit posting here, so please hold true to your word and STFU. I'm pretty sure all of us "pimply-faced kids" have heard about enough of your incessant whining and, whether you're correct or not, it's clear you're just bent on being right more than you're able to contribute something useful to the community. Sure, maybe you were walking 5 miles to school every day, uphill both ways, before Bbobynski was born, and I'm sure you have significant experience with horseless carriages. So, if it makes you feel any better, I hereby concede that, since you've been around since metal was discovered, you probably have more experience than anybody else and your way is right. There, does that make you feel better? GOODBYE ALREADY! THIS CHILDISH AND STUPID PISSING MATCH MUST END NOW!

RAD
05-09-05, 11:07 AM
I’ve been a reader and occasional contributor to this and other forums for some time now. I started reading with 30+ years in engineering.(Not automotive, but the same disciplines and philosophy applies) Now, applying my years of analytic skills and reading this string from the beginning, I’ve come to a conclusive report.

gtm2u…You’re fired.

dkozloski
05-09-05, 01:21 PM
At this point I would like to publicly apologize to Bbob and everyone else for stepping over the line a few times myself. My motivation was to try to prod some more information out of people that I was sure they knew but didn't feel at liberty to disclose. Maybe some day we'll see a "tell-all" book. Cheers.

gtm2u
05-10-05, 09:41 AM
I have been following this thread so far, but it is getting really silly.

Both you, gtm2u and Bbob are not spring chickens or cocky 20-somethings! You have life experience ahd should have enough smarts to see when a useful conversation turns into a pissing contest.

Gtm2u: you have a big chip on your shoulder - you thing that you are God's gift to mechanics and you also seem to have a strong dislike for design engineers (namely Bbob).

You seem to disagree with most of what he says. And he's been extremely valuable asset to this forum while you really haven't .

Just because you've been a grease monkey since the 60s, you aren't God!

Sorry but from the track record of Bbob and you, I have to say that I'll take his word over yours any day! But I don't blindly follow anything he says either. I apply "my" logic to whatever he says and I use only what I find useful and logical.
But I don't want to constantly question or disagree with him either.

And personally, I don't like your attitude!

Peteski

Peteski:

I don't like my attitude either!

Never have I encountered such garbage from anyone who has constalntly misquoted, misrepresented, provoked, antogonized just about every post I've written. I made a statement that Lancia used inserts and studs in their aluminum engines. I made the statement that they season their aluminum castings for 2 years before final machining. I was called a liar, every attempt was made to discredit anything I wrote, it was subject to ridicule and insult. You are damned right I have a bad attitude, when it's your turn in the barrel and someone is trying to shove it up your backside see how you like it. I for one don't especially from a grown man who's motives are all to clear. When trying to address the problems at hand that was met with denial that there were any problems.

I cite what have been industry standards for detecting a leaking head gasket and again brought under the executioner's hatchet job. Yet no proof from even a Cadillac manual stipulates the process was the acceptable method for leak detection. Again the attempts to discredit me for stating what I know and what the most recognized and respected body has stipulated are the acceptable methods. I've never failed at any repair except cameras and watches so no reason to think this will be any different. However some engineer did fail with this problem and this is hopefully addressed by using a coarser pitch thread with the new cars. But that doesn't help me and the countless others who have and will have the same problem that some engineer did fail to comprehend. It is not true that I dislike all design engineers, I dislike people who behave like what we have seen here who have to resort to abuse and personal attacks rather than address the problems at hand.

I tried ignoring him while he demanded I should tell him I had a blown head gasket for I'd had enough of his abusive shit, yet my asking 5 times what the aluminum strength was only was met with a smart ass reply.

For sure I do have a bad attitude, I'm the only one that seems to be asking questions that pose an obvious threat to what we are told doesn't exist. I know I'm in the top 99% as a mechanic, I don't know and never thought of myself as god's chosen, I do have a gift and the experience that sets me apart from most anyone else I've encountered here. I am capable of understanding that he's a company man who would loose his job if he revealed all he does know about these failures.

For you and those who may not be conversant I can see where you might feel as you do, you can hang on every word he posts as long as it's not you that is the object of his abuse. I'm not so thick skinned that his egotistical crap doesn't bother me, but I guess from his knee jerk reaction it wasn't to his liking when someone contradicted what he would have you believe that he is always right.

In conclusion the problem could have been averted had he or one of his co-workers used a proper bolt of adequate length, diameter, and pitch for the aluminum they had to use. We still don't know what is tearing threads, is it the stretch is occuring in the threads or is the block too soft or lost some properties and will no longer support the calculated engagement. Someone in the bean counting department figured out after the horses are out of the barn that they have to do something since all the block and head design changes were not keeping the failure rate to an acceptable level. We know the inserts are also failing so do you attribute that to novice mechanics not being able to read directions, use a drill, use a tap, use an insert driver, or apply oil and Locktite.

Since I cannot find a longer insert I may be relegated to using what the factory endorses, if you accept my skills are equal to the task and the inserts pull out do I have any remedy... don't hurt yourself laughing. :)

Cheers,
GTM2u

ktills45
05-10-05, 10:46 AM
GTM2u,


It's always fascinating to read how great you are.

Could you please site the statistics you're using to determine the level of failures with the N* head gaskets?

dkozloski
05-10-05, 12:28 PM
gtm2u, you're just like the old tom cat that wandered around the hanger. No matter how many times we ran him out, every time the door was opened to spot the planes he was right back inside.

dkozloski
05-10-05, 01:03 PM
BBob, something has me puzzled. If it is so important that the headbolt threads in the block be rolled threads, how does one get away with cut threads for the Timeserts? Is it the increased diameter that compensates or some other mechanism? It would seem to me that the thread fits between the block and the insert wouldn't be much different than a washing machine. Also, is there any heat treat or accellerated aging process used on the blocks or is all machine work done "as cast"?

delzy
05-10-05, 02:54 PM
GTM2u clearly has a serious case of engineer envy. It does appear that he fancies himself one though. Maybe if he earned the credential he decries, his comments would be worth the time required to read them.

BeelzeBob
05-10-05, 04:14 PM
BBob, something has me puzzled. If it is so important that the headbolt threads in the block be rolled threads, how does one get away with cut threads for the Timeserts? Is it the increased diameter that compensates or some other mechanism? It would seem to me that the thread fits between the block and the insert wouldn't be much different than a washing machine. Also, is there any heat treat or accellerated aging process used on the blocks or is all machine work done "as cast"?


There is much more engagement area with the cut threads for the timesert. The timesert tap is a special tap that makes very "tight" threads for matching the threads on the OD of the insert. I don't remember the specific thread classification but it was suprisingly tight. That is why there is some resistence to installing the timesert inserts into the female threads in the parent aluminum.

It is important to bottom the timesert and the special driver for the timesert. gmt2u noticed in one of his earlier comments that he could only thread a timesert insert onto a head bolt about 2 diameters before it "fouled" and wouldn't go any further. He seemed to state this with a sort of negative connotation but, in fact, the timesert insert is manufactured with a smaller ID thread toward the bottom to the point that it is a heavy interference. The same thing happens when you first put the inset onto the installation mandrel. If he had read the directions he could have avoided embarassing himself one more time. When the mandrel seats the timesert against the parent metal it will continue downward and fully engage the insert. As it drives into the insert it expands it into the female threads and locks it in place. Plus it forcefully seats the timesert into the female threads upsetting material and forming a very tight bond between the OD of the insert and the female threads of the parent material. This locks the insert into the parent metal and greatly contributes to it's strength in the parent metal.

The other thing that helps is the fact that the head bolt threads are now bearing against a hardened steel surface so any wear on the female threads that would have taken place as the head bolt turned against the aluminum female threads is eliminated. By eliminating this frictional part of the head bolt thread dynamic the "cut" thread on the OD of the insert is plenty strong enough.

The timesert has much more engagement due to length and larger OD. Plus, the fact that the timesert is a solid piece (rather than a slinky like a helicoil) allows it to tranfer load from any individual ID thread to the WHOLE length of the OD of the insert that is bearing in the aluminum. This adds greatly to the overall strength of the joint and adds sufficient safety factor to allow the cut threads to live fine.

BeelzeBob
05-10-05, 04:48 PM
gmt2u...per your previous posts you have a head gasket leak and are considering repairing it. You mentioned trying to install inserts and studs and such thru the head to avoid removing the head. Part of this discussion revolved around what really failed....the head gasket or the bolt threads. Your assumption seems to revolve around the head bolt threads failing causing the head gasket leak and that simply "fixing" that would implement a repair. I was trying to get the message across that your head gasket has failed....period. It was not likely caused by the bolts or bolt threads failing.

Your generation of Northstar actually rarely fails "head bolts" in my experience. And I have had a lot of 93/94 Northstars apart. It is always the head gasket that has given up due to repeated thermal fatigue aggravated considerably by corrosion in the area under the fire rings between the cylinders in the siamese area.

The 93/94/95 Northstars were factory filled with the conventional, green, silicated coolant. That silicated coolant only has corrosion protection in an all aluminum engine for about 2-3 years/24-35K miles. If it is not changed per that schedule then the corrosion inhibitors become depleted and things in the cooling system corrode. The most evident damage is generally the head gaskets failing. There are cooling passages in the siamese area of the cylinders and the depleted coolant in those passages can allow the head gasket steel substraight to corrode from the cooling passages outward. This area is very close to the fire rings of the cylinders so when the substraight collapses due to thermal loading exceeding it's weakened resiliency the head gasket starts to leak.

Probably your problem started years ago when someone did not maintain the cooling system adequately with fresh coolant. It likely has nothing to do with the bolts.

Simply replacing the bolts, adding clamp load, changing bolt strength, etc. is not going to solve your problem. You will have to replace the head gasket. I have NEVER seen a composite compacted graphite gasket live after it starts to leak and has exhibited coolant loss. Any move to "save time" by trying to substitute other fasteners will be an exercise in frustration on your part.

When you dissassemble you will likely damage a bolt hole or two due to the galvanic action between the threads of the steel bolt and the aluminum block. Shit happens. Despite the coatings, sealed cavity, and all the development work father time causes it to happen. The threads were likely fine until the bolt ripped part of the aluminum thread away, started to gall and then took out the threads above it. Only thing that cannot be speeded up in accelerated testing is this father time factor. So, after all these years the likely hood of damageing a head bolt thread removing the head bolts is high I would say. Higher than I would have said 10 years ago before 10 years of experience occurred. If you use an strong impact gun to knock the head bolts loose you stand a better chance of removing them with no damage but it is a crap shoot at this point in time.

There is a ready, easy, developed and tested fix for you if you choose to use it. Order the OEM head gasket kit that comes with new bolts and the correct, Northstar timesert head bolt kit. Simply install the timesets per instructions, install the new head gaskets with the new head bolts. Tension them according to the factory recommended torque-angle and reassemble the engine. You will be happy with the outcome and it will outlive you I guarantee.

You are the only person I have heard of yet claiming that the timeserts do not work or fail. Where did that gem come from...?? Other styles of inserts and helicoils have failed, yes. That is because they are not engineered for the specific task of the NOrthstar head bolts. Timeserts are engineered for the joint and will not fail as you suggest. Saying that the timeserts fail is pure BS and speculation on your part.

I would personally recommend the timeserts if it is apart as they are really not that hard nor timeconsuming to install and they are readily available. Cheap insurance to make sure that nothing strips when you pull the heads down again.

Before you pull your heads, though, try the combustion chamber leak check with compressed air. The plugs are easy to get at and the "tools" are simple to make. You might be pleasantly surprised at how well it works. I would be interested in hearing from you if find that it works as advertised OR if it doesn't work....


It is unfortunate that your attitude is the way it is.

Many things and "facts" that you have posted have been refuted (some at your own admission) and your lapse in logic in accepting the leak test description is unexplainable to me. Now that you are reduced to falling back on the Lancia reference it is just about over for you I think. There are no volume engine manufacturers that have ever "aged" castings for two years out of doors before machining. Get real. Manufacturers might accelerate aging of aluminum blocks with a T5 or T6 heat treat but they do not "age" them outside. Besides, the metallurgical references that I see indicate that the magority of material property change in aluminum is accomplished in 30 days or less....why 2 years...????

BTW...no one called you a liar for saying Lancias had inserts. I simply indicated that no one is using inserts in any modern engines. You brought up a low volume antique application and I laughed at it....yes. But I did not call you a liar. You made that up.

Your very first opening posts alluded to the incapability of the "Cadillac engineers" and the use of "inferior products and materials" and the assumption that the joint required redesign because it "only" lasts for over 100K miles in some cases. Yet you complain about some sarcastic posts to you subsequent to that....???... You seem to ignore logic and practical information unless YOU provide it. And your posts are like an epistle of personal attacks against me or anyone that "doubts" you. Read back thru them and have a laugh.

There are many places that I contribute on this forum. I haven't seen you on any topic other than this thread and talking about head bolts. My reputation on this forum precedes you by several years of helping people solve a myriad of problems and helping them diagnose and effect repairs in a reasonable and accurate way....whether under the shade tree or in the garage. At least many of them were armed with the facts when going to the garage or dealer for repair. The subjects in question are far ranging from driveability issues to transmissions to Cateras..... So far your only references on here are your dubious "facts" about head bolts.

Stick to the technical issues, get the chip off your shoulder and join in. Just leave out any attacks on people and they will not bite back.

Stoneage_Caddy
05-10-05, 05:26 PM
The subjects in question are far ranging from driveability issues to transmissions to Cateras......
not to mention suspension controlls for old devilles with pushrod engines !!! thankx again dude !!!!

ktills45
05-10-05, 05:33 PM
GTM2u,


It's always fascinating to read how great you are.

Could you please site the statistics you're using to determine the level of failures with the N* head gaskets?

I'll help you out...

On the Lincolnvscadillac web site, theres a poll going on head gasket failures.

Last I looked, 11% of the owners reporting had this problem.

dkozloski
05-10-05, 05:36 PM
Bbob, after WWI my dad worked for a custom body maker with the stature of Brewster and Fisher named Ehrdmann-Geider(sp). My dad made the front fenders and radiator shell by hand for one of Henry Ford's personal cars. The fenders were hand formed free hand from sheet steel and the radiator shell was made the same way from German silver. He also did gold leaf work and gold pinstriping. He said that it was not uncommon for the heavy iron block castings of the time to have some rough cuts made on them and then they would be stored over the winter to relieve stresses. I have heard the strangest interpretations of this process including that it was the rusting that did the trick. This is one of the more escoteric processes that has fallen by the wayside.

BeelzeBob
05-10-05, 05:46 PM
I'll help you out...

On the cadillacforums web site, theres a poll going on head gasket failures.

Last I looked, 11% of the owners reporting had this problem.


Keep in mind that that is 11% of the people that looked up the forum for some reason....actually a pretty small percentage if you figure that most people only look up the forum when they have a problem and want info or to vent or to commiserate. Besides, only about 124 people had taken the poll so that is hardle a representative sample of the millions of engines out there. All the others are happily driving their cars knowing nothing about head bolts or head gaskets or anything else.........

ktills45
05-10-05, 05:50 PM
Keep in mind that that is 11% of the people that looked up the forum for some reason....actually a pretty small percentage if you figure that most people only look up the forum when they have a problem and want info or to vent or to commiserate. All the others are happily driving their cars knowing nothing about head bolts or head gaskets or anything else.........

Agreed.

The poll started out with 30% saying they had problems, and as others responded it dropped rapidly.

I'm of the opinion that most folks come to the forums to either wax lyrical about their rides or piss and moan about problems.

The overwhelming majority of owners simply put gas in the tank and go without any problems at all.

BTW, the majority of owners reporting problems had over 100k miles.

dkozloski
05-10-05, 06:48 PM
Going by the number of people registered on the forum and an estimate of the number of people reporting trouble I'm betting on about 1/1000 or less.

gtm2u
05-11-05, 04:24 AM
There is much more engagement area with the cut threads for the timesert. The timesert tap is a special tap that makes very "tight" threads for matching the threads on the OD of the insert.
...

It is important to bottom the timesert and the special driver for the timesert. gmt2u noticed in one of his earlier comments that he could only thread a timesert insert onto a head bolt about 2 diameters before it "fouled" and wouldn't go any further.

The timesert has much more engagement due to length and larger OD. Plus, the fact that the timesert is a solid piece (rather than a slinky like a helicoil) allows it to tranfer load from any individual ID thread to the WHOLE length of the OD of the insert that is bearing in the aluminum. This adds greatly to the overall strength of the joint and adds sufficient safety factor to allow the cut threads to live fine.

Would have been helpful had you addressed this weeks ago rather than trying to show me up to the drunks and cheering section.
...
So when you say much more engagement, is there a value you would assign? I seem to recall something on the order of about 25% SWL from my calculations predicated on the insert being very near the bottom. Is one to infer that by increasing the diameter from 11mm to 12.75mm the advantage of a rolled female thread is lost and there will be a net gain in anchoring?? So why not just blind hole tap to a 13mm 2.0 and torque to 120ft/lbs/angle if you could find such a beast? (15/32") I didn't have a flashlight but it seemed the pick/scribe found about 1/2"-3/4" that were not threaded in the '94 block.

The problem I am having from the get go is the insert should be 45mm and not 30mm when I calculate the distance to the first thread is 1.4" and the deck to hole bottom is 3.17" on all 20. Clearly this is not reflected in what I did not read nor in evidence from any other offering posted here.

In it's current configuration the flaired top of the insert would prohibit ever attaining the the desired depth unless there is a tool to which moves the counterbore some 1/2"-3/4" lower in the holes. Rather that, cut a section out of another 20 inserts and realize another 50% insert length.

GTM2u

gtm2u
05-11-05, 07:26 AM
...
BTW...no one called you a liar for saying Lancias had inserts. I simply indicated that no one is using inserts in any modern engines. You brought up a low volume antique application and I laughed at it....yes. But I did not call you a liar. You made that up.
...

Stick to the technical issues, get the chip off your shoulder and join in. Just leave out any attacks on people and they will not bite back.

Addressing your BTW:
you are just so wrong about current production cars not using inserts. There are at least 3 Japanese cars being imported or built in the US that have them.

This is the nonsense which has constantly come from your mouth.

How is anyone supposed to get past this?? It's impossible to have an intelegent conversation and it irresponsible to those reading this forum to constantly be called a liar when you are so out of touch. I have no problem sticking with technical issues, I didn't come here to have cheap shots intending to subject me to ridicule because bbob almighty can't accept anyone else knowing fact from fiction. I was man enough to accept that I had made a math error when calculating total compressive load. The other was right or wrong I repeated what I was told came from the factory in using Helicoils. That is not many, several, some, it's exactly 2,

As for the remainder of this post the opinions expressed are just that laced with the same misreprentations.

I would add that the pressure of corrosion is generally taken as 10,000psi and if the clamp force potential of 90,000 minus say 20,000 it's not the head gasket causing the problem. If that were the case you would have sued FelPro and I would not be considering using studs twice as strong as the factory bolts.

If you get your jollies from reading the peanut gallery to bolster your lack of objectivity and give you moral support then this is pointless.

ktills45
05-11-05, 07:35 AM
Addressing your BTW:
you are just so wrong about current production cars not using inserts. There are at least 3 Japanese cars being imported or built in the US that have them.

This is the nonsense which has constantly come from your mouth.

How is anyone supposed to get past this?? It's impossible to have an intelegent conversation and it irresponsible to those reading this forum to constantly be called a liar when you are so out of touch. I have no problem sticking with technical issues, I didn't come here to have cheap shots intending to subject me to ridicule because bbob almighty can't accept anyone else knowing fact from fiction. I was man enough to accept that I had made a math error when calculating total compressive load. The other was right or wrong I repeated what I was told came from the factory in using Helicoils. That is not many, several, some, it's exactly 2,

As for the remainder of this post the opinions expressed are just that laced with the same misreprentations.

I would add that the pressure of corrosion is generally taken as 10,000psi and if the clamp force potential of 90,000 minus say 20,000 it's not the head gasket causing the problem. If that were the case you would have sued FelPro and I would not be considering using studs twice as strong as the factory bolts.

If you get your jollies from reading the peanut gallery to bolster your lack of objectivity and give you moral support then this is pointless.

GTM2u,

I have no idea whether an abnormally high proportion of N* engines blow head gaskets, but since I own one I am interested. From my own experience, Cadillacs have a 100% failure rate with the transmission mated to the 94 N* engine, however I would hesitate to site that as a reliable metric for evaluating the longevity of this transmission as I am the only one I know who had to replace one.



You offer insights into Lancias and 3 production Japanese cars. Which three? You also claim a higher then average failure rate on N* head gaskets. How high? What are the numbers?

If you insist on referring to us as drunks, at least give us something to drink. Site specifics and increase your credibility.

1996deVille
05-11-05, 12:10 PM
What an interesting thread.

Two worlds being argued. One, are the components "strong" enough to overcome failure to a point of warranty? Two, when and can these components be rebuilt?

Bottom line:

1.) The components in the design are strong enough to be stable to the 3 year/36K point. GM's responsibility ends here.

2.) The components can be rebuilt - but in most cases are not, the car goes to scrap.

Having always been a shade tree mechanic I assumed a few things about this car that shouldn't have been assumed - my fault. I should've done my homework!

1.) Could I get to most of the problematic parts w/o too much disassembly of unrelated parts? Answer, no.
2.) Was this a good car to purchase with the idea of rebuilding it, again no.
3.) The issues with the head gaskets and head bolts applies to anyone having the car past 3 years or 36K. In my case, at 114K, they're still holding - they've done their job. However, if the answer to rebuilding this engine means time-serting, then some design characteristic should have been developed into the new engine upon assembly. I understand this is a moot point because of #1 above.

I don't believe we will see the actual numbers of blown head gaskets - most people buying these cars could care less, they trade 'em in before the problems occur. That being said, if there wasn't a problem with the N* platform it wouldn't come up in the forum. The weak spot rises to the top and will rear its ugly head. This is very much like reading about the CTS-V rear end problem... yep, it's there.

The 45 to 65 age group remembers too much about yesterday's designs in a 20 to 30 age group world. We are in a disposable society, this includes cars along with almost everything else. I'm a fosil, I have to get used to this!

Hey, let's design and build a car like the Martin Guitar company designs and builds guitars - 100% lifetime "bumper to bumper" warranty to the original buyer...

... that's a moot point as well, see #1 above.

BeelzeBob
05-11-05, 01:07 PM
gmt2u....you just cannot leave out the insults, can you...???? I'll show you that I can and simply address your points after this. In the future stick to the facts and let's discuss them to increase our understanding. Example: If you were to simply ask "is it normal for the timesert insert to only screw part way on before fouling" it would elicite an explanation of why that is the case. Since you seem to know a lot about these things and get somewhat inflamed when the explaination "points out the obvious" it is hard to answer you without risking insulting your intelligence. Instead, you make a derogatory comment about the timesert not even threading on the bolt when a simple read of the timesert insert instructions would explain that to you and why it is the case. The insert will not even thread onto the timesert mandrel all the way because it is not supposed to. You have repeatedly told me how expert you are on various thread inserts so I took you at your word. Understand that a) I have no idea how much you know in detail about any of the things we are discussing. So I add detail and you get insulted. I don't add detail and you get insulted. GET THE CHIP OFF YOUR SHOULDER. b) other people than you read the post and I add details that I think are pertinent so that others, that aren't as knowlegable as you, can understand. It is no reflection on you. It is just my teaching approach. If I say something you know....skip over it and don't get insulted.


The timeserts are designed for the top flange to stop or bottom against the top of the new, cut, female threads that were made by the timesert tap. If you counterbore or countersink so that it is flush the top flange on the OD is not going to hold anything on the OD so that is pointless to do. There is plenty of OD thread to hold the timesert in the block with the head bolt loads. I have explained why the insert holds stronger in the parent aluminum than the original head bolts and I have explained that the insert has been tested and validated thru the head gasket thermal cycling, head bolt pullout tests, etc. I am not really interested in redesigning the insert on here because I will not guess at what might work better and I am not going to expend test resources doing something that has already been done. The inserted hole is stronger than the production holes were by a significant margin. It is a solid, well proven repair. There is no evidence that the timesert inserts will ever pull out. Any circumstantial evidence of inserts pulling out involves other brands of inserts. That is why timesert was chosen as the preferred repair technique and that is why they developed and we validated the special length Northstar head bolt timesert insert.

We have found that going beyond 3 diameters in thread engagement causes significant interference in the thread engagement to the point that the bolts can become difficult to drive and have high prevaling torque. High prevailing torque defeats the purpose of the extended thread engagement so the inserts were deliberately limited in length for that reason.

If the block boss is drilled with the timesert dreamer to the specified depth in the kit (a fixture is included to do this) and the insert installed to that depth the insert will have sufficient OD thread engagement in the block and the head bolt will have sufficient engagement into the timesert insert on the ID. The head bolt needs much less engagement into the hardened steel timesert than it did in the aluminum. Industry standards for a steel bolt in a steel female thread is 1.5 diameters generally for that load range. The head bolt will have at least 2 diameters of engagement into the timesert so it is fine. That is the nice thing about the timesert....being a solid insert it spreads the ID thread load over the entire OD of the insert. Since the OD thread is now in larger diameter, tight fitting female aluminum threads and it is expanded in place to actually upset some metal to seat it the insert anchors quite nicely in the aluminum threads and will hold very well.

You mention "...why not just blind hole tap to a 13mm 2.0 and torque to 120ft/lbs/angle if you could find such a beast?..." There is a ready answer. First....what is the "120 ft/lbs/angle" mean.... I am not familiar with that spec. The bolt tenioning is typically expressed as something like 40 ftlb plus 180 degrees. That is a torque angle spec. 120 ftlb is just a torque spec. Second, it is NOT desireable to increase the torque/tension of the bolt/joint. The joint is already stressed to the maximum limit of the head gasket resiliency when it if first pulled down before thermal cycling. Adding clamp load by adding torque, putting stiffer/stronger fasteners in the joint will be ineffective because it will overstress the joint. The compacted graphite gasket is designed for a specific clamp load that is achieved with the production bolts and tensioning specs. If that is exceeded then the gasket will fail much quicker as it will be overstressed. The gasket itself has a spring rate due to the material, fire ring thickness, inner steel substraight, etc...so that MUST be taken into account. Third, if one were to increase the diameter of the head bolt fasteners the clearance holes in the head and the block deck would need to be increased to an even larger diameter for tap/thread clearance. If the bolt were to 12 mm then the clearnace holes would need to be even larger for the tap and nominal true position of the holes in the various parts. The holes are currently at the largest diameter that can be designed and have adequate material strength in the material surrounding the bolt bosses and inside the head. Simply drilling the holes out large will weaken the column strengths and allow more deflection and possible collapse of the columns. Increasing hole diameter for the head bolt holes and clearance holes will damage the block and head structurally so it is not advisable.

If I am wrong about engines in current production using inserts in the head bolt holes I will be the first to admit it. I have reviewed extensive competative engine teardowns most all of which were aluminum block engines from oriental sources, European sources, and some other low volume variants. NONE of them have ever had inserts in the head bolt threads. I religously read competitive engine analysis from the press and technical trade journals including all SAE papers published on different new engine families. I have NEVER seen a reference to head bolt threads in aluminum blocks being installed. I have personally walked the BMW and Ford engine machining lines and assembly lines for their aluminum engines and no head bolt inserts were installed. If there is one out there that uses inserts I do not know about it. You indicate some do. If so, then I am wrong and I will gladly admit it. Which ones use inserts? Specifics please. And I am not interested in what Lancia did years ago. You mention 3 current production engines. Which ones are they??

BeelzeBob
05-11-05, 01:23 PM
Addressing your BTW:
you are just so wrong about current production cars not using inserts. There are at least 3 Japanese cars being imported or built in the US that have them.

This is the nonsense which has constantly come from your mouth.

How is anyone supposed to get past this?? It's impossible to have an intelegent conversation and it irresponsible to those reading this forum to constantly be called a liar when you are so out of touch. I have no problem sticking with technical issues, I didn't come here to have cheap shots intending to subject me to ridicule because bbob almighty can't accept anyone else knowing fact from fiction. I was man enough to accept that I had made a math error when calculating total compressive load. The other was right or wrong I repeated what I was told came from the factory in using Helicoils. That is not many, several, some, it's exactly 2,

As for the remainder of this post the opinions expressed are just that laced with the same misreprentations.

I would add that the pressure of corrosion is generally taken as 10,000psi and if the clamp force potential of 90,000 minus say 20,000 it's not the head gasket causing the problem. If that were the case you would have sued FelPro and I would not be considering using studs twice as strong as the factory bolts.

If you get your jollies from reading the peanut gallery to bolster your lack of objectivity and give you moral support then this is pointless.


Please correct my nonsense by telling me what volume production engines use inserts so that I can more correct in the future. I have looked for them and have not found them. Show me the light.

Not sure what you mean by the pressure of corrosion in this context. The head gasket is a distinct layer in the joint. The corrosion of the inner substraight simply causes the substraight to weaken and eventually collapse. The corrosion doesn't spread the joint. If you pick apart the head gasket after dissassembly you can frequently find the inner, expanded metal core of the gasket corroded and crumbly. That is what happens with depleted coolant that no longer has sufficient corrosion inhibitor potential. The expanded metal core or substraight acts like a spring in compression in the joint to provide the resiliency of the gasket. When it corrodes and weakens and crumbles the gasket collapses.

FelPro is not the gasket supplier......besides, why would we (or anyone) sue the gasket supplier when the customer allows the coolant to deplete of corrosion inhibitors due to lack of proper, specified maintenance?? I am not trying to shift blame or deny....just explain the facts of life. In the 93/94/95 era the best coolant available for corrosion protection was the conventional green silicated coolant. It required changing frequently due to the fact that the silicates deplete with time/miles (the silicates are sacrificial in preventing corrosion). THAT is why GM developed the DexCool coolant in conjuntion with Texaco....to provide longer term corrosion protection for the cooling systems so that things like head cracking and gasket failure due to corrosion would not be an issue. As I mentioned, on your car, the original owners who did not maintain the cooling system instigated the start of the corrosion failure that took over 100K to manifest itself. If the coolant had been maintained the head gasket would have lasted longer....it isn't the bolts or the clamp load or the joint that has failed...it is the gasket itself.


I get my jollies by providing accurate, credible information about the Northstar engine and Cadillacs in general. I enjoy helping people diagnose their problems, fix their cars quickly, simply, correctly and at the least expense possible. I could care less what the peanut gallery thinks. The people that I have helped (and there are many if you review this forum for the past several years) understand this and appreciate my help. The detractors are just noise.

As far as errors detected/corrected (only 2 ??)...what about your assertions that torque angle specs had been abandoned..?? That was a major gab on your part as they are the industry standard specification for critical fasteners. What about the leak check? No one denied that your methods had a place in the industry. I just mentioned two other, simpler approaches for the average mechanic that work, have excellent credibility (since the pressure check is used in the fastener/sealing industry world wide). Whether you believe it will work is up to you but there is adequate background for them and no one called you a liar for the tests you mentioned. If you don't agree, state your grounds for objection on a technical level and move on.

Your whole assumption about what is "going wrong" in the head gasket joint is based on your speculation. That is fine to discuss what COULD be wrong but until you take your heads off you have absolutely no idea what the problem or failure mode is. For you to dig your heels in and assert that it must be the head bolts does not show practical judgement. One member on here (I will send you the CD showing his repair and pictures of the failure if you do not believe it) had similiar symptoms, took the heads off and discovered that the bolts all had tension and the head gasket was fine. HIS problem was a tiny crack in the cylinder liner itself at the top of the bore. coolant had eventualy found a path between the aluminum surround and the cylinder liner and made its way into the cylinder via the tiny crack. It had nothing to do with the cylinder or head gasket or bolt or the design of the engine. The problem was fixed via vacuuming the coolant cavity and letting the vacuum pull an anaerobic sealing agent into the crevice and leak path which sealed up the leak. The engine was reassembled and is running fine thousands of miles later. Point is....you and I have no idea what the problem is with YOUR engine until you take it apart and see. There are a myriad of head gasket failure modes and symptoms. The final answer will be determined when it is apart. Until then, you and I argueing and you hurling insults is pointless until you know exactly what the problem is. Leak checking your engine with the pressure test I described WILL tell you what cylinder(s) are leaking so that when you take it apart you will know exactly where to look. That is about as far as the discussion can go at this point without diverting off into "what if's". Those are fine but treat them as such and allow for error as you or I may be totally wrong guessing what is wrong with your engine.

gtm2u
05-12-05, 12:51 AM
bbob It's unfortunate that you are the only one that remotely knows what really is going on. However, it is obvious that you have no respect for anyone except yourself and I see no reason to allow you to bully me and continue to misrepresent what I have said. I'm wasting my time with you, I got exactly zero out of you, what has been established is there are some gaping holes in what you should have known and that you have no respect for what anyone else knows. You have no idea of the contempt you have generated while you have had great sport screwing with me from day one. I don't give a hoot whether you ever get your head out of your arse but you are the epitome of what is wrong with Detroit.

I'm outta here.

dkozloski
05-12-05, 01:06 AM
Don't let the door hit you in the ass. Where is the list of cars that use thread inserts at original assembly? That guy would lie if the truth would do him more good.

RAD
05-12-05, 01:13 AM
gmt2u, get some help with the extra time you'll have, now that you've left. Maybe a good therapist can help you shore up that extremely fragile ego of yours...

dkozloski
05-12-05, 01:48 AM
Pride goeth before a fall.

Maxoom
05-12-05, 08:50 AM
Hey guys, I just noticed something: gtm2u's profile has changed. He's no longer claiming to be 60-something years old. His behavior was always at odds with his indicated age.

dkozloski
05-12-05, 12:29 PM
We have been H-A-D HAD. He(gtm2u) says his birthday is April 1st.

dkozloski
05-12-05, 12:34 PM
I'm betting he was some jokester collegue of Bbob's on here jerking his chain. Engineers are famous for that too.

Jack Ammann
05-12-05, 12:44 PM
Dang Guy...Why don't you just take a couple of Midol and get over it. :crybaby:



bbob It's unfortunate that you are the only one that remotely knows what really is going on. However, it is obvious that you have no respect for anyone except yourself and I see no reason to allow you to bully me and continue to misrepresent what I have said. I'm wasting my time with you, I got exactly zero out of you, what has been established is there are some gaping holes in what you should have known and that you have no respect for what anyone else knows. You have no idea of the contempt you have generated while you have had great sport screwing with me from day one. I don't give a hoot whether you ever get your head out of your arse but you are the epitome of what is wrong with Detroit.

I'm outta here.

dkozloski
05-12-05, 12:54 PM
Maybe Bbob is schizophrenic and has been writing letters to himself like the Cutoms Agent/Postmaster in "The Spiral Road" by Jan De Hartog.

Stoneage_Caddy
05-12-05, 01:03 PM
but wait my fellow conspiracy theroists .....here is my theory ....dkozloski and bbobynski are the same too !!!

check it out i bet all these are the same guy too!!! :
dkozloski
bbobynski
02Eskiii
94cadooski
Adam Bronikowski
Alski
andrew kowalski
bielawskioh
bjurkovski
bob cackowski
branski76
bruski127
Chester Lapinski
Chibski
Ckozlowski
Ctandeski
Damian Grabowski
daneski70
david plesniarski
Dr.Chris Klobukowski


In the words of One Rosco P Coltrain
I gotca i gotca !!!!
http://www.sign-here.com/gifs/images/cm2070b.JPG

dkozloski
05-12-05, 01:14 PM
Whoever the guy is he's good. Everytime he pushed that "Lancia" or "other manufacturers use threaded insets" button old Bbob would leap to the bait.

dkozloski
05-12-05, 01:35 PM
Hey stoneage, your theory would require a Polack to have several brains and most of us are accused of having half a brain.

Stoneage_Caddy
05-12-05, 01:41 PM
LOL.....amen to that im a polack myself .....

dkozloski
05-12-05, 02:26 PM
Stoneage, we may get some ridicule thrown at us but there are two areas where we can't be matched: When Poland was staring a war with Hitler in the face they chose as their leader of government the finest concert pianist that ever lived, Jan Paderewski; and If you visit a Polish household and you are able to get back out the door under you own power and walk home, they consider themselves to be failures as a host.

ktills45
05-12-05, 02:34 PM
Doh!

Good find. :p

It was still a very interesting debate.

Stoneage_Caddy
05-12-05, 02:56 PM
the finest concert pianist that ever lived, Jan Paderewski; and If you visit a Polish household and you are able to get back out the door under you own power and walk home, they consider themselves to be failures as a host.
i know that all to well ...my grandmother told me im related to that dude

dkozloski
05-12-05, 03:14 PM
During the Viet Nam era, soldiers escorting the bodies home fought over who got to attend the Polish funerals. One guy told me he got a two-fer; after the funeral was a wedding and he almost didn't survive.

Stoneage_Caddy
05-12-05, 03:48 PM
uh oh ...me thinks there is something i may not know about the polish ...or my mind is int he gutter.......i thought it was just the cooking that killed people ......talk about some colestorl rich food .....

dkozloski
05-12-05, 04:37 PM
The booze tends to flow.

Stoneage_Caddy
05-12-05, 04:42 PM
oh ...yah ...know that for sure ....tho weve kinda broken those roots over the years...altho that side ended up in the moonshine bizness somewhere along the line...i wasnt so sure there for a minute about not being able to "get out"...

steelhrd
05-19-05, 01:35 PM
I noticed that bbob without fail blames headgasket failure mostly on owners not servicing their cars. I owned mine almost all of its life had 20k on it when i bought it. had the coolant service perfomed before it was due. and bought coolant tablets every 15000 miles. So what did i miss if i did miss something i will feel better about a 4000 dollar repair bill.

rbrantlee
05-20-05, 01:05 PM
Head gasket failures on Northstar engines are NOT epidemic. Yes, some engines , depending on their service history and maintenance procedures will start to loose a head gasket with 100K and 150K and 200K on them. Do they ALL do that...??? NO. Do many of them do that...??? NO. Does this indicate that Cadillac "cheaped out"...???....NO. Does it condemn the engine...????...NO.

I bought my 98 STS with only 30K miles. Coolant looked fresh(it was DexCool) but replaced it(with tabs) for extra insurance. Started losing coolant at 35K miles out the pipes. Losing about a gallon every 500 miles. Would you help me call 1-800-GM-CARES and get them to help me out? LOL!??

I know you preach against this but do you(just by chance) have any experience with the liquid glass and/or other types of head gasket repair materials? I am only asking because I am trying to decide whether to get it sellable or replace the gaskets.

Concerning the timeserting you did a while back, would you recommend to a first timer not to use the template like you did?

BeelzeBob
05-20-05, 04:13 PM
I noticed that bbob without fail blames headgasket failure mostly on owners not servicing their cars. I owned mine almost all of its life had 20k on it when i bought it. had the coolant service perfomed before it was due. and bought coolant tablets every 15000 miles. So what did i miss if i did miss something i will feel better about a 4000 dollar repair bill.



I think you are misquoting me a bit.

I have said that the failures of head gaskets on the 93/94/95 Northstars are commonly found to be caused by corrosion of the gasket from the inside out due to lack of cooling system maintenance.

That doesn't mean that a high mileage, well maintained 93/94/95 Northstar might not eventually fatigue and fail a head gasket.

Eventually something starts to wear or take the strain of high miles/hours/years of operation and it just might be the head gasket in this case.

Not to say that it is always a corrosion problem in a 93/94/95 due to neglect but that it FREQUENTLY is the cause based on my observations. I have seen head gaskets fail for other reasons such as a fatigue failure of a fire ring and even one "head gasket repair" that was done because of leakage of coolant into the cylinder due to a small crack in a cylinder liner. Very unusual and seemed just like a head gasket but it wasn't the gasket at all.

The 93/94/95 engines were susceptable to corrosion damage from depleted coolant because they were filled with the green, silicated coolant that required frequent replacement to maintain adequate anti-corrosion performance.

Internal corrosion due to lack of cooling system maintenance is pretty much a moot point from 1996 and later due to the introduction of DexCool which, at the very worst case, offers significantly longer anti-corrosion life and at the very best is good for life. So, head gasket failures past that point are not blamed in any fashion on lack of maintenance. Never have been...at least not by me. I know why the DexCool was put into production (to protect things like head gaskets from long term corrosion problems) so I wouldn't blame a head gasket failure on it....

There are a lot of factors involved with the head gasket and head gasket failures. There is no question that one of the most highly stressed parts of an all aluminum engine is the head gasket. It works under intense pressure, is subject to regularily changing loads from thermal gradients, warmup, cooldown, etc.. It is highly stressed in overheat conditions. It is not surprising that a head gasket might be one of the first things to start to show the effects of wear and tear in an all aluminum engine. I just try to put it into perspective by pointing out that the engine is virtually unscathed at 100K for other wear and tear so the things that people have had to replace/rebuild/repair at that point on other engines are no longer a concern. At 100K-150K and beyond, some of the head gaskets are apparently starting to fail based on input from this and other forums. This obviously leaves room for improvement but still is not too bad of a performance for an all aluminum engine with the specific output of a Nortstar.

The collateral damage of the head bolt threads is something that is really more of a learning experience with age than anything else. After operating for 10-12 years with the bolts in place it seems that the threads are being damaged more regularily than not. There is a perfectly adequate, affordable and easy to install repair for this. The engine is not a throwaway because of this nor is it irrepairable.

Failures on the later model engines are certainly regretable but, it is still an all aluminum engine that stresses the head gasket highly and there are going to start to be some failures due to normal wear and tear on the engine as it goes over 100K-150K. For one to fail at a low mileage like 35K as indicated is really abnormal. I have no idea what would have caused a failure at those low miles. Since we do not know the service or use history of the car prior to your purchase it is impossible to speculate.

If you want to try "liquid glass" (never heard of it) or any other head gasket temporary fix in a bottle have at it and let us know how it works out. I have personally NEVER seen any of those products help in the least and there is really no engineering reason to believe that a product poured into the cooling system is going to be strong enough to do what a head gasket couldn't. But, who knows, maybe miracles can happen. I don't preach against/for anything. Just relate my own personal experience and personal knowlege. It gets repeated a lot because people do not know how to use the "search" feature so the same thing gets said over and over. It is the same thing...not me preaching.

As far as "freehanding" the timeserts without the jig... It is really not that hard to do. The existing bolt hole is a pretty good alignment guide as is. If you have a reasonably steady hand, take the time to mark the depths of the drilling and tapping accordingly, I don't see why it couldn't be done by most anyone. But, if you have never tapped a hole before I would recommend using the jig. There is nothing magic about the timeserts. They are simply a threaded bushing. You drill out the old threads, tap, screw in the insert and seat it with the special mandrel that expands the lower threads into the parent material. The crucial item for the jig is that the hole is drilled along the correct centerline so that the head bolt (which is long) threads straight into the insert. So it needs to be "reasonably" straight in the bottom of the hole. The hole is also a stepped hole. The timesert "dreamer" (half drill, half reamer) is stepped accordingly and the jig and collet supplied guarantees that you stop at the correct depth. If you can judge this for yourself, that is not a problem. I simply wrap electrical tape around the dreamer to act as a stop against the deck surface as a depth marker. The main thing about the timesert kit with the jig, collets and such is that it is almost totally idiot proof. It would be hard to mess up the job if you use the jig. I would recommend it unless you have considerable experience as a machinist or drill and tap a lot of holes. If this is the first time you are going to tap a critical hole use the jig. A mechanic friend of mine did a Northstar head gasket job as a side job and he free handed all 20 holes with no problem what-so-ever. But his day job is a skilled trades machine repair man so he does that type of thing frequently anyway...but he had never had a Northstar apart before.


I see a lot of references regarding the timeserts pulling out or the possibility thereof. They will not pull out if done correctly. Timesert makes "Bigserts" not because timeserts pull out but because helicoils and other, non-approved, repairs pull out and then the hole is too large to repair with a normal timesert. Sooo....to save the blocks that were butchered with helicoils or other inferior (for this application) inserts the BigSerts were developed.

There is also another case for bigserts. When the hole is step drilled with the stepped "dreamer" and someone goes in too far the material for the threads is drilled out and then there is a need for a Bigsert to effect a repair....this has happened more than once when someone tries to free hand the repair and forgets to check the drill depth...see above.

As far as using the coolant supplement pellets. As has been reviewed many many times, the coolant supplement pellets are simply a sealer. In a Northstar they are cheap insurance against a nuisance leak in the cooling system. The have nothing to do with the anti-corrosion characteristics of the coolant and using them has nothing to do with head gasket life. They are simply a cooling system sealer to prevent leaks. Head gasket failures and (the use of) coolant supplement pellets are completely unrelated and have no bearing on each other.

dkozloski
05-22-05, 09:26 PM
I think the "liquid glass" is a corruption of the antique name for sodium silicate, "water glass". This makes pretty good sealing glue for exhaust systems when soaked up in boiler insulation. The stuff is water soluble but when it dries looks just like glass and seems to handle heat pretty well. It's easy to come by because it is also used to candle eggs. Ask an old farmer about that one.

Spyder
05-23-05, 01:56 AM
I've seen a "liguid glass" additive that's supposed to seal headgasket leaks and water leaks and such. Sure it doesn't work, but that's what it's suppsoed to be...just another brand of the same 'ol junk.

rbrantlee
05-23-05, 03:32 PM
Failures on the later model engines are certainly regretable but, it is still an all aluminum engine that stresses the head gasket highly and there are going to start to be some failures due to normal wear and tear on the engine as it goes over 100K-150K. For one to fail at a low mileage like 35K as indicated is really abnormal. I have no idea what would have caused a failure at those low miles. Since we do not know the service or use history of the car prior to your purchase it is impossible to speculate.

If you want to try "liquid glass" (never heard of it) or any other head gasket temporary fix in a bottle have at it and let us know how it works out. I have personally NEVER seen any of those products help in the least and there is really no engineering reason to believe that a product poured into the cooling system is going to be strong enough to do what a head gasket couldn't. But, who knows, maybe miracles can happen. I don't preach against/for anything. Just relate my own personal experience and personal knowlege. It gets repeated a lot because people do not know how to use the "search" feature so the same thing gets said over and over. It is the same thing...not me preaching.

As far as using the coolant supplement pellets. As has been reviewed many many times, the coolant supplement pellets are simply a sealer. In a Northstar they are cheap insurance against a nuisance leak in the cooling system. The have nothing to do with the anti-corrosion characteristics of the coolant and using them has nothing to do with head gasket life. They are simply a cooling system sealer to prevent leaks. Head gasket failures and (the use of) coolant supplement pellets are completely unrelated and have no bearing on each other.

BBob - I wasn't even going to try calling GM until you wrote the first paragraph above. My brother was a service manager at a Pontiac dealership and told me I would be wasting my time but you inspired me. I called 1-800-GM-CARES. Told them about losing coolant out the exhaust at 35K on a 98 STS. Ten minutes later she offered me either 50% on a new engine or 50% to just replace the head gaskets and timesert the holes on my engine!!!!! My lower jaw is still on the floor. LOL!!! Is there any reason I should go for a new engine and not fix mine? I know it will still have the cross-hatch marks, etc. New engine installed is about $7800 vs about $3500 for gaskets/timeserts. I have the cash but don't want to throw it away unnecessarily. I guess I could just wait till they break it down to check everything out.

I didn't mean to imply you 'preach'. LOL! I was just making the point that you have always made the excellent point that these engines weren't designed to run with pure water and/or without the thermostat, which is required during the treatment process for some of these head gasket repairs in a bottle. That is why I was asking for any personal experiences. I do use the search feature. I must have missed that one. On the other site, I actually read(or browsed through) every post you ever posted. It took me the better part of a day.

Lastly, when I said for extra insurance, I meant replacing the DexCool with fresh DexCool. That is why I put 'with tabs' in parentheses. Once again, Thanks BBob.

cl1986
05-24-05, 01:19 AM
I've seen a "liguid glass" additive that's supposed to seal headgasket leaks and water leaks and such. Sure it doesn't work, but that's what it's suppsoed to be...just another brand of the same 'ol junk.

Thats statement is wrong!! LOL well sometimes.

My 91 deville had a head gasket out at about 175k and was loosing coolant. A little dose of the liquid glass once a year and it is still going with over 198k on it and i sold it at 190k. The guy who bought it loves the car and thought he stole it from me at $800, which is probrably true, i could have parted it out for more than that.

The one funny thing about that car was the ac woudl always leak and get low on refrigerant and the car would start getting bad milage, like from 24 down to 15 or so. Filling the ac system would bring back the 24 MPG and im not making this up, it did this about 4 times, evey time the ac didnt work so i added a can and back up to 24 MPg it went.

charles smith
06-16-05, 01:41 AM
High Oil Consumption, Pulled Headbolts, Blown Head Gaskets, Bars Leak, Unstable Temps...Seems too frequent not to be an eyebrow-raiser.

Let me start out by saying that I'm the proud owner now of a 96 ETC with the N*. I Love the car, it's looks, it's power and am impressed by the overall engineering of everything on the vehicle Except for one thing... the cooling system. I've noticed firsthand and reading on here thru countless posts that it's "typical" for temps during normal driving to cycle between around 190 to 230(some have even reported up to 250). I may be an "old school" wrench but even as much as technology has changed over the past few years, I am Not surprised that blown head gaskets and high oil consumption are mentioned so frequently.

Over the years it has become a well known fact that aluminum engines are more heat critical. Me, I like to keep my vehicles nice and in excellent working condition(and for a long time). This is why all of this is so bothersome. In the twenty-some odd years of GMs I've owned they've all had stable running engine temps and... I've religiously changed all my stock 195 thermostats out for 180's. I'm sure I'm gonna spark some heated debates here on that subject(and it is Not the subject I'm aiming to drum up some friendly discussion on) but it has worked VERY well for me over the years. I myself wrench and my past experience with this keeps gaskets from getting brittle and losing their seal, oil lubrication qualities high and better power and fuel economy from less detonation. The big thing to me is the longevity. In the many vehicles I've owned I've Never had Any internal mechanical failure, leaks or even oil consumption problems Ever. I've Never had any emissions passing problems either(Except for 2 of my 170,000 + mile vehicles needed a new cat as the pellet type just plain wore out.) I keep my vehicles for a long time and I also like to drive them "hard" from time to time too. So call it just good luck if you want.

Getting back to the subject of my post...
230+ running temp is too high for my liking(that's just my personal opinion). Sure maybe gasket and oil technology has changed over the last few years but that's just plain cooking hot in my book. Rings gummed up with "coked" oil... I'm not surprised. Early & excessive oil consumption...I'm also not surprised. Failing gaskets...you don't say. Just think how much even more heat your engine sees with heat soak(after turning the car off). Also not to mention you'd Never make it home having to put just plain old water in your cooling system from way out in the boondocks after say a hose failure. But OK. Lets just say "normal" it is per GM. What my bother is mostly about is in the stop and go temp fluctuations of this car. Think of it this way... if the aluminum of the engine is constantly changing from 190 to 230 as you idle then drive: 230 - 190 = 40 degrees of CONTINUAL temp fluctuation. If you don't think that's a big deal drop a 30 degree ice cube into a 70 degree glass of soda....but Keep doing it. Sure that's kind of an extreme comparison but that much of a continuous "Swing" CAN'T be good for the expansion of an aluminum engine held together with steel bolts. Bars leak or not, it just seems like a problem waiting to happen from a machinists and a mechanics standpoint. All of my past vehicles had stable operating temps, why not this one I've been asking myself...

So in I jump under my hood... replacing the thermostat(from the dealer), checking the water pump, belt and tensioner, pulling the radiator and inspecting the tanks & tubes, changing the hoses and ultimately the coolant(after a good flush). Everything is A+. Even the coolant lines, restrictors and the heater core all flow well. Still I get temps all over the place(190-229). That's even in the cold Chicago weather here. My fans are functioning(kick on LOW at 225), but still even with the vehicle moving in very cold airflow it's still all over the place. Definitely not stable.

Can someone tell me... am I seeing things or is the thermostat mounted on the coolant RETURN side INTO the block?(cooled water coming FROM the radiator flows thru the thermostat???) Please tell me that's NOT so!

(Unless there's something wrong with my eyesight it looks like the RETURN line from the heater core is the only thing that heats the thermostat up to open. And that would be mixed with the cooled water coming from the radiator too!)

I have had this unstable temperature problem for over a year. I replaced the radiator (the radiator exploded while in the local Cad' dealer's checkin booth), thermostat, water pump, over $500 in all, and the dealer told me the car was unfixable, that I should junk it. Turns out to be a collapsed water hose with a pinhole high pressure leak. $18 and ten minutes and the problem is fixed. I wound up solving the problem myself. My wife has promised to murder me if I ever cross another Cad' dealer's threshhold again. The coloing system design is absolutly moronic, the rubber water hose runs all way across the car transversely and is the weakest part of the system.

Change to 20W50 mo0tor oil to solve the consumption problem. It worked for me on two different Cadillacs. They are designed to turn to shit at 50.001 miles.

nota
06-16-05, 11:23 AM
my two cents after reading this whole thread

the GM guy is usefull but giveing the GM CORP LINE

I have 4 N* in the garage all had head gasket failures AT LOW MILES
I got them in a package deal along with a Fiero with extencive mods
to use a N* in a stick [getrag] with a holly commander CPU
from a head caddy teck who pulled them at his dealership
one has been rebuilt useing the timecerts both the heads and mains

he said that gasket failing is the common flaw of this motor
and happens so often thats about all he does is fix them
as is the needed timecerts to fix it
thats at a small town dealer

droping the cradel is the only way to go about any major repairs

side note about ten pages back the rolls with the merlin is REAL
I saw a artical in hotrod a few years ago with pic on it
more of a drag show car then a real driver and that motor takes up most of the car with the driver in the very back

mcowden
06-16-05, 01:13 PM
Well, charles smith and nota, I think you're both not only wrong, but you're also crazy. The manual specifically says not to use 20W-50. What on earth would give you the idea that you should use it? Do you think you know more about engineering than the people who designed the engine? Your ridiculous ideas suggest that you definitely do not. Good luck keeping that thing on the road. When your 20W-50 engine dies a painful death due to lubrication failures, you'll probably be back to piss and moan about how the oil pump is the major failure of the Northstar, right? The dealer told you it was junk because he wanted to sell you a new car. Here's a little friendly advice: Dealerships are not your friends, you should follow the recommendations in the manual, and both long and short hoses get holes in them. They're all facts of life. To the best of my knowledge, you're the first person to come in here and complain that the length and routing of the radiator hoses is a major weak point of the cooling system.

Hey notas, guess what? The mechanic fixes a lot of Northstars because he's a Northstar mechanic. Dealerships like to fix head gaskets because they live on the warranty money, ESPECIALLY in small town dealerships, whether the gaskets need replacement or not. They'll tell you that your tire is low because of a bad head gasket if it will get them the warranty money, and they'll tell you the motor is shot to get you into the showroom to buy another one if they think you're sold on Cadillacs and have the scratch. Relying on a dealership mechanic for advice about the statistics on repairs is like going to a shoe store to ask for advice on a heart condition. If you want a laugh, ask him why the head gaskets failed. Why don't you ask about the statistics of failures versus following the recommended cooling system maintenance procedures?

JimHare
06-16-05, 02:35 PM
There's a quick and relatively easy way of determining the 'extent' of head gasket failures, but I'm not sure anyone without "Eyes Only" clearance would be able to get accurate numbers.

1) How many Northstar-engine equipped automobiles have been manufactured since Day 1?
2) How many actual head gasket failures have been reported?

The problem with #2 is that I'd bet that a lot of gasket repairs have been done unnecessarily, due to dealer misdiagnosis or whatever. I'm not saying that those of you who have had the HG replaced were dreaming, but from all accounts, that seems to be a fairly common diagnosis for almost any drivability problem reported to a dealer...

"The car misfires and stumbles a bit, plus I can't the the power antenna down"...

"Must be the head gasket. $8000 and we'll have you outta here in a week.."

As BBob and others have noted, the forum is NOT visited by the literally millons of N* owners who have never had a problem with their cars...it's only us nuts and other unfortunates who come here - some to rant and rave, some just to rave, some just to rant...

I would be extremely suprised if even 5% of all N*s ever built have needed a HG replacement.

BeelzeBob
06-16-05, 03:47 PM
If head gasket failures were epidemic then the head gasket kit sales thru service parts would be astronomical......it isn't....

The moronic "long" hose is on the pressure side of the system....what is so moronic about a long hose on the pressure side??? Any hose can get a pinhole leak for a variety of reasons. A simple system pressure test should have found that problem if it was done...or done correctly. A long hose on the suction side of the system might be considered moronic due to it's added propensity to collapse...but the suction side hose to the water pump inlet is short.....for that very reason.

So...other than the hose that is too long for your liking....what is so moronic about the cooling system...??? Besides the fact that you found a service establishment that cannot diagnose problems...???


Funny thing too about those small town dealers....I visited on recently in a small town in Canada. It was a full line GM dealer that sold all the GM products. I talked at length with the tech in the garage that did all the Cadillac work. He had never done a head gasket on a Northstar and indicated just the opposite....that they work well and people liked them because they warmed up fast in the winter. He thought the engine was pretty bulletproof based on his experience since it came out. I guess you have to pick the right small town to get the story you want....LOL.

ktills45
06-16-05, 06:51 PM
I talked to the mechanic at the local Caddy dealer.

He said the N* was one of the best engines ever made, and that he's been working on them for 10 years. The only thing he mentioned was that they used oil.

Sounds like he puts in alot of head gaskets also. ;)

nota
06-16-05, 09:43 PM
well the 4 motors are real
as are the bad head gaskets
and I got them because he was building a autoX racer for his kid
who as kids will do switched intrests to race bikes from cars

and bargan hunter that I am I got the whole lot
inc a like a like new tricked out fiero with 18" wheels with race rubber
13" vett brakes
adjustable coilovers with custom tube a-arms and anti roll bars ect
4 motors 2 trans and a ton of other spare bits
for less then you guys are quoted to redue ONE N*
and way less then 1/2 the value of the parts

prior hunts have found stacks of take out N* motors
being sold as scrap priced lots that I passed on
while looking for the right deal :coolgleam

Supreme97
06-21-05, 01:07 AM
Bar's Leak works, but it eats away at the impellers in the water pump everytime you use it, causing the engine temp to slowly rise when traveling at low speeds or idling.

eldorado1
06-21-05, 01:27 AM
Bar's Leak works, but it eats away at the impellers in the water pump everytime you use it, causing the engine temp to slowly rise when traveling at low speeds or idling.

http://cadillacforums.com/forums/images/smilies/16suspect1.gif

hnettles
06-21-05, 01:33 AM
I found this site (and this thread) via a Google search. It has taken
me a good two hours to read the entire thread, and I did learn a lot.

I have a 1998 Cadillac Sedan DeVille, which was purchased used from a
Cadillac dealer in 2001, with 35K miles (still under factory warranty).
This car has been babied and maintained meticulously -- I always change
oil and filter at 3K miles, not 7.5K. The full 100,000 mile service
was performed at 96K -- I even replaced the radiator, as there were
cracks in the plastic tank. There are new Michelin tires on the ground
(16k miles on them), all 4 brakes were rebuilt less than 20k miles ago.
This car has always gotten 22 mpg on average (documented), and it still
rode and drove beautifully up until very recently.

A few months ago, the "Coolant Level" warning came on, and I added
approximatly two quarts of a 50/50 mix of DexCool and distilled water.
Two months later, it did it again, then one month, then two weeks.
I could not find a leak, and I was NOT familiar with the head gasket
problem, so I took the car in to an independent repair facility.
The mechanic told me he used ultraviolet dye to find a leak in the
water pump, and he charged me $453 to replace the water pump (ouch!).
Two days after I got the car back, the "Coolant Level" warning came on
again, so I returned to the mechanic.

This time, he found dye on the outside of the intake manifold and
diagnosed a leaking intake manifold gasket. He did not want to attempt
the repair, and advised me to take it to the dealer. He also refused
to refund my $453 for the water pump (crook!). At that time I started
searching online, found and read this entire thread, which took several
hours (grin). I parked the car, and started searching for a new car.
After several days, I found the new car I wanted (not another Cadillac,
thank you very much), and attempted to drive the Cadillac to the dealer
for an appraisal as a trade in. The dealer I was headed for is about
50 miles from my house, and I checked the coolant level (full) before
leaving the house.

Approximately half-way to the dealership (25 miles), all hell broke
loose. "Overheating", "Low Coolant", "Turn off AC", "Pull over and
stop engine", etc. My Cadillac finished up the trip on a wrecker, being
hauled to the nearest Cadillac dealer (not where I was originally headed).
That was Saturday afternoon/evening. This morning (Monday), the service
department at the dealer advised me I have a blown head gasket, and the
approximate cost for repairs will be $4,000 (possibly more).

This car is now scrap metal. It is worth somewhere in the vicinity of
$4,000 to $5,000 in trade in value, and will cost approximately the same
to be repaired. Perhaps the reason more head gaskets are not being sold
is because the cars get scrapped?

I do not care how eloquently "bbob" defends this engine, any time it
costs $4,000 to replace a head gasket, something is ROTTEN IN DENMARK!!!

RAD
06-21-05, 02:02 AM
Bars leak (standard formula) is the exact chemical composition as the GM 'pellets'. It's essentially ground up walnut shells and ginger root. There is nothing in it's chemical or physical makeup that will cause harm to the impeller, or any other component.




Bar's Leak works, but it eats away at the impellers in the water pump everytime you use it, causing the engine temp to slowly rise when traveling at low speeds or idling.

Supreme97
06-21-05, 12:47 PM
I found this site (and this thread) via a Google search. It has taken
me a good two hours to read the entire thread, and I did learn a lot.

I have a 1998 Cadillac Sedan DeVille, which was purchased used from a
Cadillac dealer in 2001, with 35K miles (still under factory warranty).
This car has been babied and maintained meticulously -- I always change
oil and filter at 3K miles, not 7.5K. The full 100,000 mile service
was performed at 96K -- I even replaced the radiator, as there were
cracks in the plastic tank. There are new Michelin tires on the ground
(16k miles on them), all 4 brakes were rebuilt less than 20k miles ago.
This car has always gotten 22 mpg on average (documented), and it still
rode and drove beautifully up until very recently.

A few months ago, the "Coolant Level" warning came on, and I added
approximatly two quarts of a 50/50 mix of DexCool and distilled water.
Two months later, it did it again, then one month, then two weeks.
I could not find a leak, and I was NOT familiar with the head gasket
problem, so I took the car in to an independent repair facility.
The mechanic told me he used ultraviolet dye to find a leak in the
water pump, and he charged me $453 to replace the water pump (ouch!).
Two days after I got the car back, the "Coolant Level" warning came on
again, so I returned to the mechanic.

This time, he found dye on the outside of the intake manifold and
diagnosed a leaking intake manifold gasket. He did not want to attempt
the repair, and advised me to take it to the dealer. He also refused
to refund my $453 for the water pump (crook!). At that time I started
searching online, found and read this entire thread, which took several
hours (grin). I parked the car, and started searching for a new car.
After several days, I found the new car I wanted (not another Cadillac,
thank you very much), and attempted to drive the Cadillac to the dealer
for an appraisal as a trade in. The dealer I was headed for is about
50 miles from my house, and I checked the coolant level (full) before
leaving the house.

Approximately half-way to the dealership (25 miles), all hell broke
loose. "Overheating", "Low Coolant", "Turn off AC", "Pull over and
stop engine", etc. My Cadillac finished up the trip on a wrecker, being
hauled to the nearest Cadillac dealer (not where I was originally headed).
That was Saturday afternoon/evening. This morning (Monday), the service
department at the dealer advised me I have a blown head gasket, and the
approximate cost for repairs will be $4,000 (possibly more).

This car is now scrap metal. It is worth somewhere in the vicinity of
$4,000 to $5,000 in trade in value, and will cost approximately the same
to be repaired. Perhaps the reason more head gaskets are not being sold
is because the cars get scrapped?

I do not care how eloquently "bbob" defends this engine, any time it
costs $4,000 to replace a head gasket, something is ROTTEN IN DENMARK!!!That sucks. For that price, you can get a used engine.

BeelzeBob
06-22-05, 12:28 AM
This time, he found dye on the outside of the intake manifold and
diagnosed a leaking intake manifold gasket. He did not want to attempt
the repair, and advised me to take it to the dealer. He also refused
to refund my $453 for the water pump (crook!).

I do not care how eloquently "bbob" defends this engine, any time it
costs $4,000 to replace a head gasket, something is ROTTEN IN DENMARK!!!


FYI there is no coolant in the intake manifold nor any coolant passages thru it so a "leak at the intake manifold" is impossible.

Have you priced replacing head gaskets on ANY engine lately....???

BeelzeBob
06-22-05, 12:30 AM
Bar's Leak works, but it eats away at the impellers in the water pump everytime you use it, causing the engine temp to slowly rise when traveling at low speeds or idling.


This is absolute nonsense. The traditional BarsLeaks products will do absolutely no harm to the water pump impeller. None. Quite the opposite. After 50,000 miles the coolant supplement in the system is rendered somewhat ineffective because the tiny fibers that comprise the coolant supplement/sealer get chopped up by the water pump impeller and it looses it's ability to seal.

RAD
06-22-05, 12:59 AM
Before anyone jumps to any conclusions, I strongly suggest you price the same repair on a Mercedes SL 500, or a Lexus SC. Try any highend overhead cam V8 these days....


[I do not care how eloquently "bbob" defends this engine, any time it
costs $4,000 to replace a head gasket, something is ROTTEN IN DENMARK!!![/QUOTE]

Spyder
06-22-05, 02:13 PM
I'm guessing that they cost just as much...or more?

Dooman
06-23-05, 08:14 AM
For that same $4000, I was able to do head gaskets, water pump, oil gaskets, starter, alternator, hoses, 4 new rotors with factory pads, battery, related gaskets and coolant, oil, and filter, serpantine belt.. All in one visit, on my 99 STS.

Spyder
06-28-05, 01:51 AM
DIY or at a shop somewhere?

Dooman
06-28-05, 10:16 AM
It was done by my local mechanic, who gets the referrals from all the local dealers who do not want the work or whose prices scared the owners away. Him and his mechanic both owned Eldorado models over the last few years..

Leah
07-14-05, 01:23 PM
I've got an idea. Let's all back up a step, take a breath and start over. It's obvious that this is an excellent chance for all of us to learn something from each other. GTM2U, could you give us some background to kind of establish your credentials, so to speak? I'm retired after a long and varied career. I was a journeyman machinist in a custom machine shop at the age of seventeen. Since then I have worked at everything from nuclear powerplants to guided missiles and computers to managing an aircraft engine overhaul shop and finally retired as the facilities and ground equipment manager of a regional airline. Bbob is a very long time Cadillac Northstar engineer who has been in the program since it's inception. Give him a chance to explain where he is coming from. I think he was a little short with you because there has been a barrage of attacks lately from less than credible sources that he has had to defend.
Welcome to the discussion.
Since you worked with aircrft engines, maybe you could offer some insight for me. I am a commercial pilot student and every day we are given little scenarios for fun to go home and work out. The scenario today is that I am the operator of a air taxi service and one of my 4-seater's (just say cessna 172 RG) loses a gasket on take-off. The pilot safely aborts the take-off and stops on the runway. This is the fourth time for this problem in the last month. On the maintenece end of things, how would you deal with this re-occuring problem?
If you could offer some insight, I would appreciate it :)! thx *Leah*

dkozloski
07-14-05, 01:35 PM
If you are an air taxi operator and you have four engine failures on takeoff in a month the FAA will be making your decisions and failure analysis for you. Other than that, you need to have your maintenance department explain the failure mode to you and also explain why they can't fix it. They need to call the Lycoming factory service department and tell them what's happening, ask if anyone else is reporting the same scenario, and what is to be done about it. The FAA will already have contacted you and be all over your rear end like a rash. You then need to see a shrink to find out why you didn't do all this after the second incident.

Fiero STS
02-21-07, 12:02 PM
Wow, that took along time to read.

AlBundy
02-21-07, 03:48 PM
Yes, this is one of my favorite threads. You learn alot.

stutz427
02-23-07, 06:59 PM
Ok just to keep this great thread going. First I have learned a lot and while not a auto engineer, I am a customer of their products and have to ask If GM knew about this problem for years, and the fix is a relatively simple one (when assembling and engine) why in the world would they have not corrected it by now. I love my SLS but also worry about the head gasket problem and maybe this is one of the reasons resale value is so low. From my perspective GM just does not get it. A cheap fix on what is sold for $50,000 just does not make sense to me.What is even worse if to leave the problem go on for year to year. Yes there are many cars that never have this problem, but if I were working for GM I sure would be watching sites like this. My guess is if Toyota had this problem you can bet the next year it would be gone. GM still has a ways to go and the customer is telling them that. I am not so sure they are hearing it as loud as they should be.

Patrick7997
02-24-07, 10:55 AM
Stutz, to answer your question, there are too many lawyers and accountants floating around the halls of these companies.... not just GM....

If at some point, say, hypothetically, in model year 2001, a "new" head gasket arrangement appears on Northstar V8's, that is tantamount to admitting that there was a problem with the old ones. And, again, continuing our hypothetical example, me and everyone else with a mid to late '90's Northstar would file a class action lawsuit to have our defective head gaskets replaced...

I assure you, our hypothetical lawyers would have a field day with the fact that a "new" head gasket design appeared.... basically, GM admitting they had a problem, knew they had a problem, tried to hide it, etc.....

Even if GM wins the hypothetical lawsuit, it will cost them millions to defend themselves....

If they lose, it's a hundreds of millions of dollars nightmare....

Enter the hypothetical accountants, who advise, in the great tradition of one of our former presidents, to deny, deny, deny, deny, and hope for the best....

And so far, it's working very nicely.

Also, very pleasing to the accountants, extended warranty sales are way up, and certified pre owned vehicles are commanding a price premium... all healthy developments, from their narrow perspective....

This is a hypothetical example. I'm not saying..... I'm just sayin'....

And don't be so sure Toyota is any different. They're in an old fashioned cockfight over these sludged engines, and their recalls are on an interesting parabolic trajectory.... Toyota merely enjoys a free pass from the auto press, which may not go on forever....

BodybyFisher
02-24-07, 01:25 PM
You know while many have said this is a great thread, it sickens me to read it. Its like watching CNN, the glass is half empty, the sky is falling, everything is a conspiracy and everything sucks. I couldn't imagine myself even suggesting that the NS was designed wrong, the set of brass spheres a statement like that requires is incredible.. To suggest that GM has NOT redesigned a part as it would admit wrongdoing fits the CNN MO to a T... I came here looking for a higher level of discourse and thought I found it, but I really don't think a higher level exists anywhere anymore. I guess I have to get over this realizing that this country is split 50/50 down the middle and that one out of every two people I meet, will have an opinion out 180 from mine.

dkozloski
02-24-07, 03:49 PM
You know while many have said this is a great thread, it sickens me to read it. Its like watching CNN, the glass is half empty, the sky is falling, everything is a conspiracy and everything sucks. I couldn't imagine myself even suggesting that the NS was designed wrong, the set of brass spheres a statement like that requires is incredible.. To suggest that GM has NOT redesigned a part as it would admit wrongdoing fits the CNN MO to a T... I came here looking for a higher level of discourse and thought I found it, but I really don't think a higher level exists anywhere anymore. I guess I have to get over this be realizing that this country is split 50/50 down the middle and that one out of every two people I meet, will have an opinion out 180 from mine.
Watching CNN will contaminate anybodies brain.

BodybyFisher
02-24-07, 04:24 PM
Watching CNN will contaminate anybodies brain.

So true man, its amazing they can say, "The Most Trusted Name in News" with a straight face :bigroll:

More phony doctored photos arriving all the time to prove our bias views :)

JimHare
02-24-07, 05:41 PM
If at some point, say, hypothetically, in model year 2001, a "new" head gasket arrangement appears on Northstar V8's, that is tantamount to admitting that there was a problem with the old ones.

Not sure you'd be able to prove that point very easily. Incremental engineering changes, especially nine years apart, do not necessarily mean the prior design was flawed - or everyone who ever bought a FM radio would sue the makers of their AM sets.

All I know is that I've got over 325,000 miles on Northstar engines with no failures of any powertrain parts whatsoever.

AlBundy
02-24-07, 05:50 PM
I agree new & improve design doesn't mean flawed old design especially since the old design still works.

Mark Bunds
02-26-07, 11:43 PM
My Mom's 94 Deville northstar needed a water pump at 270000 miles. What a piece of crap!

BodybyFisher
02-27-07, 12:18 AM
My Mom's 94 Deville northstar needed a water pump at 270000 miles. What a piece of crap!

The moon 238,580 miles away! :) I'd be on the phone with GM, you won't make it back!

krimson_cardnal
02-27-07, 01:35 PM
Yes, this is one of my favorite threads. You learn alot.
Hey guys, :thumbsup: thanks for digging this out and bringing it foward, GREAT thread, good info in between the cracks. K_C

stutz427
03-04-07, 01:40 PM
Have had a chance to think about this some more and am digging in my heels a little more on forcing the issue. In my past life I was manager of a tier 1 auto supplier and one of the items we had to learn was continuous quality improvement. Seems like in the late 50's a gentleman by the name of Eugene Demmings worked with the Japanese Auto companies on designing a quality improvement process. Year after year they tried to make things better. It was felt by doing this, their customers would help them increase sales. Unfortunately for us these firms listened and became good at improving. The result of course as we all know was increased sales at the expense of our domestic firms. The American mfgs did not take to this concept and were caught flat footed. Just this week, while they have made great strides Consumers report came out with results saying much of the same thing. Don't get my wrong, I buy American products and do like my SLS, but I just wish GM would ask consumers like us what our main problems are, and in the next model year fix it. I am sure if you asked all of us for the 10 bad things we wish were changed, most would be easy and cheap fixes. I will list a few for example. My frustration is that many of these are from model year to the next and since the body changes are small it should be easy to do. I can understand when the whole platform is changed you might take a while to find problems but!!!. Ok so to keep this thread going

1) Headgasket
2) Trunk seal
3) Cabin air filter (99 & up)
4) Cost of shocks
5) Oil consumption
6) Low beam headlights
7) Shifter in the way of storage compartments and cup holder
8) Front end shimmy
9) Poor braking
10) Fuel consumption

See some of these would not be costly or hard to fix

BodybyFisher
03-04-07, 04:14 PM
The result of course as we all know was increased sales at the expense of our domestic firms. The American mfgs did not take to this concept and were caught flat footed. Just this week, while they have made great strides Consumers report came out with results saying much of the same thing.

1) Headgasket
2) Trunk seal
3) Cabin air filter (99 & up)
4) Cost of shocks
5) Oil consumption
6) Low beam headlights
7) Shifter in the way of storage compartments and cup holder
8) Front end shimmy
9) Poor braking
10) Fuel consumption


What year car do you have you don't mention it. You have over simplified the problem greatly, in terms of why the Asian manufacturers have made inroads into the US market. In my humble opinion its not quality based. In addition, you cite a magazine that I wouldn't wipe my butt with, its highly biased. See this thread > http://caddyinfo.ipbhost.com/index.php?showtopic=12664

You mention the following as problems:
1) Headgasket (you are hearing about and giving too much weight to the engines that have the problem, I don't think its as bad as these boards make it out to be, many NS's have high mileage on them)
2) Trunk seal (I don't hear this as a big problem, my trunk is dry)
3) Cabin air filter (99 & up) (wish I had one, why is this a 'problem', hard to change?, take it to the dealer)
4) Cost of shocks (this is an issue I wish they were less expensive, I guess its the result of the electronics)
5) Oil consumption (the engine has been designed with an aggressive cross hatch and it consumes oil, do the WOT procedure)
6) Low beam headlights (what, does this mean?)
7) Shifter in the way of storage compartments and cup holder (you mean when its in park?), ok GM move the storage compartments
8) Front end shimmy (see this link and notice my response to the member that talked about the "trademark" shimmy, time to get a good mechanic, most can't get out of their own way http://caddyinfo.ipbhost.com/index.php?showtopic=12828&st=0 )
9) Poor braking (the braking is fine, I have a problem with the mechanics or owners that do improper brake jobs, if you don't have FOUR wheel brake jobs done at the same time, including caliper bushings, turn the rotors and flush the fluid and bleed the brakes, lets not talk about bad braking). Owner's that ONLY do front brakes, don't bleed the system and don't replace the bushings and don't turn the rotors to lightly clean them up are looking for trouble... And..I know there is a contingent out there that believe that turning rotors is unnecessary but I believe giving the new pads a non-directional square surface is imperative.
10) Fuel consumption (most NS's get about 22 to 25 mpg on the road and +15 to 17 around town, I dont see that as an issue).

Last year, the CTS was criticized for having a cheap feeling and looking interior by the car rags. If you have ever sat in an AUDI, you know what they are talking about, the finishes in an AUDI are amazing. However GM stepped up to the plate and fixed it, and got kudos for its interior, GM rose to the challenge > http://caddyinfo.ipbhost.com/index.php?showtopic=12830&hl=interior

The Northstar has CONTINUALLY improved since its introduction, see this >> http://autospeed.drive.com.au/cms/A_1569/article.html

Since 1990 the Cadillac has constantly improved, power, dependability, engines, and systems, they are not sitting on their hands. Their marketing has been revamped, they were racing to promote the name, and they now have a 100,000 mile warranty...

boatman
04-11-07, 05:27 PM
Anyone heard form Bezlbob? I need his help desperatly!

JimHare
04-11-07, 07:31 PM
The person to whom you refer, our erstwhile "Guru" left the board some time ago, legend has under pressure from his employers. The jury is still out as to whether he pops in here on occasion with a "nom de keyboard" offering additional pithy advice. Like the Dead Sea Scrolls, all we can do is pore over his earlier writings..

urbanski
04-11-07, 07:52 PM
Anyone heard form Bezlbob? I need his help desperatly!

just post your question for the forum and see who replies.

Ranger
04-11-07, 08:55 PM
He has returned on occasion, under a different name of coarse, but I have not seen him in quite a while.

thatwolfofmine
04-12-07, 04:32 PM
Can someone help me? First of all I LOVE my Caddy. It's a 96 Deville, 1 owner, bought at 86,000 and now has 96,000. We used to run it a lot. It overheated a few times in the beginning because unbeknownst to us, we needed the pellets and the DexCool. Yes, I know it's right on the radiator, but we weren't doing the maintenance ourselves, and needless to say, the person that was isn't doing it anymore. So....we took her to a radiator specialist, cause we thought maybe there was a leak, since it started overheating a lot. I mean, we check the levels daily, and starting out full of fluid, we may go for about an hour and overheat. I don't understand it, and I don't want to take it to a dealer and get ripped. Does anyone have any suggestions? Oh, the gaskets supposedly are not blown, but "leaky".

Ranger
04-12-07, 06:12 PM
If you are talking about the head gaskets being leaky, then you need to replace them. Lack of pellets and using other than Dex, will not cause it to overheat.

Oh, the gaskets supposedly are not blown, but "leaky".
No difference. A "blown" head gasket is just another way of saying that it is leaking.

zonie77
04-12-07, 07:57 PM
Does anyone have any suggestions? Oh, the gaskets supposedly are not blown, but "leaky".

The suggestion is have the gaskets replaced.

It is possible to do it yourself if you are so inclined.

1997seville
04-12-07, 11:20 PM
The person to whom you refer, our erstwhile "Guru" left the board some time ago, legend has under pressure from his employers. The jury is still out as to whether he pops in here on occasion with a "nom de keyboard" offering additional pithy advice. Like the Dead Sea Scrolls, all we can do is pore over his earlier writings..

I dont want to start anything but I came across something interesting. I have been around almost a year and have heard the "Guru" mentioned many times. After reading this thread I finally got to read some of his posts. But here is the interesing part. I was doing a google search on the n* and came across an old post from 2003. He was posting questions that a N* engineer wouldnt ask. So I did a little more searching and it seems in his early days on here, he did not know anything technical about the n*. It just seems that somewhere along the way he suddenly was an expert. Here is the thread that I found in case anyone cares.

http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/226-important-push-northstar-once-week.html

Ranger
04-13-07, 12:14 AM
That was not him. He is not from Ft Lauderdale (assuming that was not changed) and that is not his style of writing.

dkozloski
04-13-07, 12:38 AM
The real Guru went by Bbob and/or Bobinski. Beezlebob was used to refer him in an effort to work around filters that were installed on the forum after he got in trouble. He was a GM Powertrain engineer of more than 35 years. He wrote articles and gave lectures on using the Northstar as a powerplant in experimental aircraft. I had some private communications with him and he was the genuine article. I've done some searches on his real identity and he still gets around in engineering circles. We're lucky we had him as long as we did. Where he got into trouble was giving accurate and engineering based answers to real problems that were at odds with what GM management was trying to put out. My guess is that management was being fed bum dope by production people trying to cover their ass.

1997seville
04-13-07, 06:35 AM
OK that makes perfect sence. I kept seing others in the post call him bbob but that is not what the name said. That just seemed weird, because in this post, he obviously seems to know what he is talking about. It's too bad he had to leave, I know he must have been very helpful to a lot of people (obviously not to a couple it this post).

Ranger
04-13-07, 11:37 AM
He was a virtual encyclopedia and is sorely missed.

Cadillacboy
04-13-07, 01:16 PM
Ranger, you also know too much of great and useful info.
My personal opinion is that he might still be a lurker .Where I get this idea from is that I looked at some of his posts the last time he posted was more than a year ago but he still seemed a supporting member and max supporting member duration is 1 year.

AlBundy
04-13-07, 05:25 PM
I dont want to start anything but I came across something interesting. I have been around almost a year and have heard the "Guru" mentioned many times. After reading this thread I finally got to read some of his posts. But here is the interesing part. I was doing a google search on the n* and came across an old post from 2003. He was posting questions that a N* engineer wouldnt ask. So I did a little more searching and it seems in his early days on here, he did not know anything technical about the n*. It just seems that somewhere along the way he suddenly was an expert. Here is the thread that I found in case anyone cares.

http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/226-important-push-northstar-once-week.html

I also ran across that thread while hangin out in the archives and thought WTF, Katshot giving Bbob advice about how to fix his N*. You must admite given their exchanges it does read kinda funny.:histeric:

Ranger
04-13-07, 10:03 PM
Like I said, I have seen him hear once in a while. I have heard that he does appear in other sections more often, but I don't frequent those sections. Also like I said, he uses a different screen name now.

boatman
04-17-07, 10:10 PM
Well, thing of it is that it is more of a general metalurgy block sealing question more than anything and not much to do with Cadillac itself. If anyone knows of him or his whereabouts, can you tell him to stop by and PM me? This is a very technical question and I can post it, as it has to do with sealing and aluminum blocks, but I dont think it belongs here for the most part. Thanks

AlBundy
04-18-07, 05:32 PM
Post the question as there are a few well knowledged members here who have talked with Bbob and might have asked him the same question.

cadillacmike68
04-22-07, 02:09 PM
this thread is STILL going ???:eek:

I guess that's good, because now my 2000 Eldorado is leakinga small amount of oil. I crawled under it and it seems to be coming from several small bolts that look to be holding the oil pan. The problem is that I can only get a wrench on about 3/4 of them!

It doesn't appear to be losing oil in any noticable amount - couldn't tell from the dipstick and no real loss between changes, but every so often there is a quarter sized sopt on the garage floor.

I re-checked a few times, the bolts I tightened look ok, but the ones I can't get to are still showing evidence of leakng.

This is not the "case halves" problem or is it?? And, can I just leave it alone or will it get worse

Ranger
04-22-07, 09:59 PM
Hard to tell if it is the halfcase or the pan from here, but it will not likely get any worse. If it is the halfcase it will be wet from the halfcase seam down. If it is the pan gasket, it should be dry above the pan. There is a procedure to slow down a pan gasket leak.

thatwolfofmine
04-24-07, 11:58 AM
if there are no warning lights then QUIT WORRYING.

I get a temp reading of 250 and above, then my radiator starts to hiss, the engine gives an "idiot" warning to turn off the engine, then it turns itself off. I don't think it's okay for my lac to run at 250. And she doesn't think so either. I replaced the thermostat, because that's what I was told was wrong. 2 days later, when the weather got a little warm (75 degrees) it overheated again. Any suggestions?

thatwolfofmine
04-24-07, 12:01 PM
The suggestion is have the gaskets replaced.

It is possible to do it yourself if you are so inclined.

Not even!! I will get the labor for free if I get the parts though. And I can get the parts for a little above wholesale. What exactly will I need?

Ranger
04-24-07, 12:41 PM
if there are no warning lights then QUIT WORRYING.

I get a temp reading of 250 and above, then my radiator starts to hiss, the engine gives an "idiot" warning to turn off the engine, then it turns itself off. I don't think it's okay for my lac to run at 250. And she doesn't think so either. I replaced the thermostat, because that's what I was told was wrong. 2 days later, when the weather got a little warm (75 degrees) it overheated again. Any suggestions?
Check the usual. Surge tank cap, purge line, water pump belt tensioner do a cylinder pressure test or have the coolant tested for exhaust gases. Any bubbling (false boiling) in the surge tank when first started?

thatwolfofmine
04-27-07, 05:04 PM
Check the usual. Surge tank cap, purge line, water pump belt tensioner do a cylinder pressure test or have the coolant tested for exhaust gases. Any bubbling (false boiling) in the surge tank when first started?

Actually, the water bubbled out of the surge tank. We don't know why that happened. It was the weirdest thing.

Ranger
04-27-07, 08:44 PM
Time to get a cylinder pressure test or coolant exhaust gas test done.

BlueMoon
05-11-07, 12:30 AM
Wow. My thread still lives on. It's been awhile since I've been on here. Glad to see "the community" is still thriving. Alot of still the same troubles/posts I see tho. :want: Hope you are all out enjoying that 4-valve-per-cylinder aluminum V8 to it's fullest.

I've received a few PMs of people asking me what if anything I've been up to since the start of my thoughts in this thread. Unfortunately I didn't have enough posts to be enabled to PM back. So my apologies to those that tried to contact me. I really wasn't ignoring you. I only drop in here once in a blue moon ya know. :leaving:


For those that are interested, after my last post on this thread, I became So irritated I went out and modified my coolant system and moved on with life. What I did was I moved my(a) thermostat over to the OUTLET side of the block, modified the fan kick-on temps and have been out beating the P#$$ out of my N* and enjoying it for the last 2 years running at 184-187 degrees(187-190 MAX). So far no head gasket/coolant/headbolt issues(although about 74,000 miles from a previous owner @ 220-240 do exist on the clock). I've had no negative issues performance, reliability or emissions wise either. Just positive.

I've never posted a picture online in a thread, but here goes for those that are interested.....(They say a picture is worth a thousand words. Here's two...)

cadillacmike68
05-27-07, 12:44 AM
How did you get your car to display the current engine coolant temp??? What year and model car?? (I have a 2000 Eldorado ELC -convertible) thanks.

AlBundy
05-27-07, 04:58 PM
There is a process in the Tech Tips section. I'm not sure about what years. Check it out.

rd62rdstr
05-27-07, 07:15 PM
I just came across your thread. Late start, also a newbie. Bought a 97 Cadillac Concours DeVille. It ran fine for a couple of months, temps were stable. It started to overheat, badly. I stopped driving it for about 4 months. I replaced the hoses, water pump, thermostat, radiator, pellets, and coolant. I then had it tested for exhaust gases. None present...Thank God! My concern now, is I drive it and it runs perfectly fine and stable at the mid line for about half a day. After that it will wander up and down from half way point to the 3/4 point. This to me does not appearto be right at all. The next morning, I will take a look in the surge tank and it appears to be down a bit lower. I top it off with more coolant. and repeat the same results. I have taken it back again for another exhaust test, and again it passed. I also have a 2000 Chevy Astro, aluminum with electric fans for those of you not familiar with it. It runs a stable 185-190 at all times regardless of temperature or idling.

P.S. I am very interested in your modifications made. Could you please send me a more in depth how to and ictures to my email address? Thanks in advance. Sal rd62rdstr1@aol.com

Ranger
05-27-07, 09:02 PM
Temps fluctuating from 1/2 - 3/4 is not normal. A coolant gas test, if positive, is proof positive that a head gasket has failed. The opposite is not true. Do a cylinder pressure test to be sure.

cadillacmike68
05-27-07, 10:03 PM
I just came across your thread. Late start, also a newbie. Bought a 97 Cadillac Concours DeVille. It ran fine for a couple of months, temps were stable. It started to overheat, badly. I stopped driving it for about 4 months. I replaced the hoses, water pump, thermostat, radiator, pellets, and coolant. I then had it tested for exhaust gases. None present...Thank God! My concern now, is I drive it and it runs perfectly fine and stable at the mid line for about half a day. After that it will wander up and down from half way point to the 3/4 point. This to me does not appearto be right at all. The next morning, I will take a look in the surge tank and it appears to be down a bit lower. I top it off with more coolant. and repeat the same results. I have taken it back again for another exhaust test, and again it passed. I also have a 2000 Chevy Astro, aluminum with electric fans for those of you not familiar with it. It runs a stable 185-190 at all times regardless of temperature or idling.

P.S. I am very interested in your modifications made. Could you please send me a more in depth how to and ictures to my email address? Thanks in advance. Sal rd62rdstr1@aol.com

Ummm, did you check BOTH cooling fans. they both need to be working. a couple years ago, late afternoon, I was driving from Tampa to St Pete and EVERY time i stopped the temp gauge would drift hotter. When I got moving, it went down. When I got to the meeting (the Local Cadillac Club of course) I checked the fans, one of the - the primary one - was not running.

These modern cars are very sensitive to the airflow across the radiator. I can hear the fans switch on and off several times a minute on some cars. If a fan is not working correctly, it WILL overheat.

rd62rdstr
05-30-07, 03:51 AM
I took a look at both fans and they were both working. I did notice today that I left the positive termonal on the battery slightly loose. I tightened it and this cleared up what looked like a short (some lights flickering). I thought perhaps the fans were not working at times due to this as well. However I drove the car afterwards and once again it wandered up and down. I have had the fluid tested for gases twice. Both times it appeared to be fine.

Ranger
05-30-07, 12:08 PM
Check the purge line to be sure that it is clear and flowing.