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



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Tommy Deville
05-30-07, 08:32 PM
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.


Perhaps your temp guage isn't working right, its possible.

charles smith
09-07-07, 07:28 PM
I went through this high oil consumption problem with my two past Cadillacs and the solution was the same for both of them. My 1996 Concours owners manual says "do not use 29W-50 oil in this car. My 1985 Seville started excessive consumption at about 50K. My 1996 Concours started it at about 150K. In both cases, I switched to 20W-50 oil, problem solved. Cadillac does not want a lots of old Cadillcs on the road loaded with "servant class" people, they want their cars in the junk yards asap after the warrenty has expired. My Concours exihibited excessive temperatures, and exhibited the tendency to accelerate on it's own when the temperature was high. I took it in to get the problem fixed, and it burst the radiator while in the Cadillac dealers checkin area. They fixed the radiator and gave me a 'cussing out' when I came to get it back, and told me I should immediately take it to a junk yard, leaving my wife in tears. A few days later, I opened the hood when it got hot again and got hit in the face with a spray of hot water. I discovered the water hoses had delaminated internally and was stopping up intermittently, causing it to run hot. I have found that all Cadillac dealers service shops have been openly hostile after I drove the cars beyond their warranty. I now drive a Mercedes.

dkozloski
09-07-07, 07:51 PM
I went through this high oil consumption problem with my two past Cadillacs and the solution was the same for both of them. My 1996 Concours owners manual says "do not use 29W-50 oil in this car. My 1985 Seville started excessive consumption at about 50K. My 1996 Concours started it at about 150K. In both cases, I switched to 20W-50 oil, problem solved. Cadillac does not want a lots of old Cadillcs on the road loaded with "servant class" people, they want their cars in the junk yards asap after the warrenty has expired. My Concours exihibited excessive temperatures, and exhibited the tendency to accelerate on it's own when the temperature was high. I took it in to get the problem fixed, and it burst the radiator while in the Cadillac dealers checkin area. They fixed the radiator and gave me a 'cussing out' when I came to get it back, and told me I should immediately take it to a junk yard, leaving my wife in tears. A few days later, I opened the hood when it got hot again and got hit in the face with a spray of hot water. I discovered the water hoses had delaminated internally and was stopping up intermittently, causing it to run hot. I have found that all Cadillac dealers service shops have been openly hostile after I drove the cars beyond their warranty. I now drive a Mercedes.
Take it easy! You're giving us grouchy old fart conspiracy theorists a bad name.

cadillacmike68
09-11-07, 10:07 PM
I don't get the same response at my local dealer. I don't take my 95 Fleetwood with 190,000 miles on it there for much - because I can replace most accessoroes on my own and any decent shop can replace a steering or suspension component on this car, but when they do see it they always compliment me on it and my other cars.

Jesda
09-17-07, 06:54 AM
You know what gets old about this forum? People making excuse after excuse for design flaws. If you venture out to other automotive forums, you will find that indeed, forums are an exaggeration for the rate of real-world problems. However, there is a consistency of certain types of problems across various brands and models.

The Infiniti Q45, Lexus LS400, and Fords-Lincolns-Mercurys with the DOHC 4.6 have EXTREMELY RARE occurrences of head gasket failures, especially compared to FWD Northstar Cadillacs and Oldsmobiles. There is a regular and unusually high occurrence of this kind of failure with the Northstar. No, not every one of the many thousands of Northstars on the road will have problems, but a larger percentage certainly do compared to other DOHC aluminum V8 engines.

I'm tired of the excuses from fanatics. Hopefully GM made some improvements when converting the Northstar for RWD use. I'd like to have an XLR one day.

blb
09-17-07, 04:00 PM
You know what gets old about this forum? People making excuse after excuse for design flaws. If you venture out to other automotive forums, you will find that indeed, forums are an exaggeration for the rate of real-world problems. However, there is a consistency of certain types of problems across various brands and models.

The Infiniti Q45, Lexus LS400, and Fords-Lincolns-Mercurys with the DOHC 4.6 have EXTREMELY RARE occurrences of head gasket failures, especially compared to FWD Northstar Cadillacs and Oldsmobiles. There is a regular and unusually high occurrence of this kind of failure with the Northstar. No, not every one of the many thousands of Northstars on the road will have problems, but a larger percentage certainly do compared to other DOHC aluminum V8 engines.

I'm tired of the excuses from fanatics. Hopefully GM made some improvements when converting the Northstar for RWD use. I'd like to have an XLR one day.

Jesda......well said, and I agree 100%.

It's just amazing to me that so many people will justify this Northstar design flaw in various ways, and then actually go out and buy another one.......especially at a time when there are so many other great cars and powertrains to choose from.

97Concours1
09-20-07, 10:12 AM
Jesda......well said, and I agree 100%.

It's just amazing to me that so many people will justify this Northstar design flaw in various ways, and then actually go out and buy another one.......especially at a time when there are so many other great cars and powertrains to choose from.

What is strange is they had a chance to fix it in the redesign for 2000(?), and didn't. I see discussions of problems with those too. Oh well, this just gives me the opportunity to buy one with the problem really cheap, and correct it for myself.

kaykirk
09-21-07, 03:17 PM
What is strange is they had a chance to fix it in the redesign for 2000(?), and didn't. I see discussions of problems with those too. Oh well, this just gives me the opportunity to buy one with the problem really cheap, and correct it for myself.

actually, they did change the design some, at least on the head gaskets...they made the head bolts longer. :yup:

clarkz71
09-21-07, 04:26 PM
The Infiniti Q45, Lexus LS400, and Fords-Lincolns-Mercurys with the DOHC 4.6 have EXTREMELY RARE occurrences of head gasket failures, especially compared to FWD Northstar Cadillacs and Oldsmobiles. There is a regular and unusually high occurrence of this kind of failure with the Northstar. No, not every one of the many thousands of Northstars on the road will have problems, but a larger percentage certainly do compared to other DOHC aluminum V8 engines.
.

I think this just proves that cooling system maintenance is more important
on the Northstar and the others resist lack of maintenance better.

Spend the $20 or $30 it costs for coolant every 2 years and you'll be fine.

blb
09-21-07, 09:13 PM
I think this just proves that cooling system maintenance is more important
on the Northstar and the others resist lack of maintenance better.

Spend the $20 or $30 it costs for coolant every 2 years and you'll be fine.

Coolant maintenance isn't going to prevent the headbolts from pulling out of the block. Many failures are occuring before the first scheduled coolant change. The issue here isn't lack of maintenance, it's lack of a robust design.

clarkz71
09-22-07, 07:31 AM
Coolant maintenance isn't going to prevent the headbolts from pulling out of the block. Many failures are occuring before the first scheduled coolant change. The issue here isn't lack of maintenance, it's lack of a robust design.

You need to do a search on the topic, it is lack of maintenance
There is nothing wrong with the design.

Research it before you speak.

97Concours1
09-22-07, 10:08 AM
Clarkz71,

You are making Jesda's point from his previous post shown below. It can't be stated any more clearly:


You know what gets old about this forum? People making excuse after excuse for design flaws. If you venture out to other automotive forums, you will find that indeed, forums are an exaggeration for the rate of real-world problems. However, there is a consistency of certain types of problems across various brands and models.

The Infiniti Q45, Lexus LS400, and Fords-Lincolns-Mercurys with the DOHC 4.6 have EXTREMELY RARE occurrences of head gasket failures, especially compared to FWD Northstar Cadillacs and Oldsmobiles. There is a regular and unusually high occurrence of this kind of failure with the Northstar. No, not every one of the many thousands of Northstars on the road will have problems, but a larger percentage certainly do compared to other DOHC aluminum V8 engines.

I'm tired of the excuses from fanatics. Hopefully GM made some improvements when converting the Northstar for RWD use. I'd like to have an XLR one day.

"Research it before you speak." you say.

If YOU research it, you can only come to the conclusion that it is underdesigned (for the real world).

97Concours1
09-22-07, 10:46 AM
There is a term in the engineering world called "Factor of Safety". It is a value that describes how overdesigned (or underdesigned) something is. In other words, how "safe" is the design against failure. Bridges have a Factor-of-safety value of something like 100. That means they are 100 TIMES (not 100%) overdesigned for the maximum load that they will ever carry. Cranes have a Factor-of-safety of five (5) I believe. I think the Factor-of-safety for the aluminum Northstar head bolt threads is about one (1). So yes, you can say that it is an adequate design, but if anything happens there is no reserve strength to resist failure.

blb
09-22-07, 11:05 AM
You need to do a search on the topic, it is lack of maintenance
There is nothing wrong with the design.

Research it before you speak.


Please expalin to us all how a failed headgasket could possibly be due to the lack of cooling system maintenace when it failed before the first scheduled coolant change as recommended by GM?

clarkz71
09-22-07, 04:01 PM
Please expalin to us all how a failed headgasket could possibly be due to the lack of cooling system maintenace when it failed before the first scheduled coolant change as recommended by GM?

Well first let me say I'm an ASE certified and Mercedes Benz factory trained technician with over
20 years experience , so I'm not a DIY or internet mechanic.

Second, what car are we talking about that failed before the 1st scheduled
cooling system service.

Your car?
A 95 or older caddy with green coolant
A 96 or newer caddy with Dexcool?
How many miles and how many years old?

Give me this information and I'll tell you why I think it blew the HG.
I know many of the members on this forum replaced their HG and posted
picture of the old rusted out HG from depleted anti corrosion inhibitors.
Coolant also gets in the head bolt threads of the block corroding them
causing them to pull.

By the way, I can't tell you how many Mercedes I replaced head gaskets
on while they were in warranty before the 1st scheduled coolant service.
So it can happen on ANY car. Do they all have a design flaw?

As far as having to install time-certs, nothing new here either.
Mercedes first all aluminum sohc V-8 had the same problem with pulled threads.
They had a better system though, instead of a jig like time-cert's that
you have to move to each cylinder MB had a steel plate a half in thick
that looked like a headgasket. So you could do all the head bolt threads
at the same time. This was on the 81 to 83 116 engine. 380SL and 380 SE/SEL
They fixed the problem on those by nickel plating the head bolts on 84 & up.

clarkz71
09-22-07, 04:03 PM
Clarkz71,

You are making Jesda's point from his previous post shown below. It can't be stated any more clearly:



"Research it before you speak." you say.

If YOU research it, you can only come to the conclusion that it is underdesigned (for the real world).


Everybody is entitled to their opinion. .:jerkit:

97Concours1
09-23-07, 07:09 AM
Well first let me say I'm an ASE certified and Mercedes Benz factory trained technician with over
20 years experience , so I'm not a DIY or internet mechanic.

Second, what car are we talking about that failed before the 1st scheduled
cooling system service.

Your car?
A 95 or older caddy with green coolant
A 96 or newer caddy with Dexcool?
How many miles and how many years old?

Give me this information and I'll tell you why I think it blew the HG.
I know many of the members on this forum replaced their HG and posted
picture of the old rusted out HG from depleted anti corrosion inhibitors.
Coolant also gets in the head bolt threads of the block corroding them
causing them to pull.

By the way, I can't tell you how many Mercedes I replaced head gaskets
on while they were in warranty before the 1st scheduled coolant service.
So it can happen on ANY car. Do they all have a design flaw?

As far as having to install time-certs, nothing new here either.
Mercedes first all aluminum sohc V-8 had the same problem with pulled threads.
They had a better system though, instead of a jig like time-cert's that
you have to move to each cylinder MB had a steel plate a half in thick
that looked like a headgasket. So you could do all the head bolt threads
at the same time. This was on the 81 to 83 116 engine. 380SL and 380 SE/SEL
They fixed the problem on those by nickel plating the head bolts on 84 & up.

I guess I should be comparing apples to apples here. It sounds like failed head bolt threads are somewhat common anytime the block is aluminum. I tend to make the mistake of comparing them with the reliability of cast iron blocks (apples to oranges).

I bought a 97 Deville fixer-upper with 94K miles on it. It had a blown head gasket on the right (rear) bank in the back corner (#7 cylinder). That corner head bolt thread was pulled. I thought it may have been caused by the proximity of the hot crossover exhaust pipe to the side of the block near the head bolt threads. Could this have been a corrosion issue instead?

clarkz71
09-23-07, 08:32 AM
I bought a 97 Deville fixer-upper with 94K miles on it. It had a blown head gasket on the right (rear) bank in the back corner (#7 cylinder). That corner head bolt thread was pulled. I thought it may have been caused by the proximity of the hot crossover exhaust pipe to the side of the block near the head bolt threads. Could this have been a corrosion issue instead?

Yes, corrosion is a very likely possibility. I've seen old coolant eat a hole
through an aluminum thermostat housing on Mercedes engine's more then
a few times.

Your DeVille should have had the coolant replaced at least twice being a
10 year old car. Remember it's every 5 years "OR" 100K miles for Dexcool
Me personally I would be changing coolant in a Dexcool
car at least every 3 years to be safe.

And another thing to keep in mind, just because there are servcie records
stating the coolant was changed doesn't mean it was. There are a lot of
technicians that will only empty the surge tank and not drain the engine
to save time because they are on flat rate. It's all about making money.
I've personally seen this done at several dealers I've worked at.

Ranger
09-23-07, 05:12 PM
There are a lot of
technicians that will only empty the surge tank and not drain the engine
to save time because they are on flat rate. It's all about making money.
I've personally seen this done at several dealers I've worked at.
That's criminal, but I don't doubt that it happens. Hopefully it is very rare.

Chrisllawson
09-26-07, 12:42 AM
I woulds like to reply about the comet about what other mechanic think.........

"It's also seemingly "popular" that if you ask any mechanic what the "weak point" of the N*'s is and what they've commonly seen
thru the past few years, guess what they're gonna say???? Yes, you guessed it...head gaskets. But, it seems most of them will say it's the Dexcool that caused it. On the flipside there's my point on the temps being all over the place and High. Me, I don't see anything wrong with dexcool. I also don't see anything wrong with the design of the mating surfaces or the gaskets or the bolt threads themselves either so far."

I had four different shops tell me that I need new head gaskets, and all four shops was wrong. They were wrong becuase like alot of mechanics do not totaly understand or do not want to understand the N* cooling system. I went to the manual myself ( I am not a Mechanic but I am mechanicly inclined) and it was a $4 fix. You should really red the manual on the N* it really helped me. From what I can see is alot of mechanics out there has herd at one time or the other that the N* engine is just a pain in the ass to work on so they suggest one of the most expensive repairs to fix and the get away with for the most part. That way if they have a problem or they replace the gasket and it still has the same problem they have also bought them sometime to figure it out.

SpiritF4
11-06-07, 08:02 PM
Chrisllawson said:
I had four different shops tell me that I need new head gaskets, and all four shops was wrong. They were wrong becuase like alot of mechanics do not totaly understand or do not want to understand the N* cooling system. I went to the manual myself ( I am not a Mechanic but I am mechanicly inclined) and it was a $4 fix."

Pray tell what on any Caddy is $4 fix instead of a HG ???

SpiritF4
11-06-07, 08:17 PM
Also, Ranger,

How to check purge line for flow, pls?

Ranger
11-06-07, 08:24 PM
Pray tell what on any Caddy is $4 fix instead of a HG ???
Surge tank cap.


With the engine at idle (cold, so as not to burn yourself) pull the 3/8" purge line at the surge tank. If it spits coolant, it is clear. Quickly plug it back on and clamp it. If it doesn't, rev the engine a bit (flow will increase with RPM). If still no flow, shut it down, locate and clear the obstruction.

SpiritF4
11-07-07, 12:42 PM
Ranger,

Let’s see if I can correctly summarize a few things from this incredible thread:

Headgasket Replacement Prevention, Testing, and Replacement Tips.
1. This site is an outstanding resource. BBob had some excellent insider info and a thick hide, being pulled in the wrong direction many times by extraneous comments. Ranger is also way up there toward 150 on a 0-100 scale as a resource in time of need / frustration / confusion. All our input should be Info Q & A, giving links to verification as necessary. Thank you, Ranger (and BBob if you are out there). They are more like experienced doctors (not gurus) and sometimes there is expensive (but excellent) medicine for what needs curing.

2. Corrosion happens when you have two different metals (gasket material between aluminum block and heads), a liquid medium, and electric current. Heat increases the rate of corrosion. There is no poor engineering or faulty advice from these folks; it is simple physics. The tabs, DexCool, etc. are corrosion preventive measures, not “plugs” for a corroded gasket or leak stops. Make sure maintenance procedures and schedule are followed for flushing/adding coolant and add the tabs to old style coolant (sigh… that was where I found out the hard way!)

3. The Testing Procedure for whether to replace HeadGasket (previously overheated engine or not) is:

a) Remove Surge Tank cap; check fluid level & color. Add proper color coolant with 60 coolant/40 distilled water ratio. (Any tap water added chemicals will enhance corrosive activity.) Flush cooling system if color is not a “fresh” color (green/yellow for ‘93/’94/’95 or red thereafter). At cold idle, check for bubbles. Bubbles = either compression gasses, or unpurged fluid.

b) At cold idle, pull the 3/8" Purge Line at the surge tank. If it spits coolant, it is clear. Quickly plug it back on and clamp it. If it doesn't, rev the engine a bit (flow will increase with RPM). If still no flow, shut it down, locate and clear the obstruction. If flow is still slow, check water pump belt tension. Proper tension is ____. “Low Coolant” light comes on when system is ____ quarts low. Best to check it often, since mine never came on before I got an “Engine Overheat” light. Once purge line is clear and flows fast, if you still get bubbles in the Surge Tank,

c) Test coolant for exhaust gas, or,

d) With a radiator pressure tester, check cap popoff pressure (mine is 15psi and make sure it holds at least 13psi.) Then apply to surge tank, start cold engine, and watch for any pressure build. If it climbs to 15, shut it down, noting the engine temp and time it took to get there. It is probably time to get a new headgasket if it gets to 15 psi way before it gets to ___ degrees within ___ minutes. (In my case, it got there in only 10 minutes and 135 degrees = new HG time; sigh.)

e) A/C on at any engine temp will get one fan running. Other fan kicks on at 225-235 degrees. If it does not, then that one needs fixing.

f) If you want to make a compression check to see which cylinder(s) leak, go ahead, but once you know you have to replace the HG, that is a waste of time imho. Better to spend your time figuring out the car’s value vs. the cost of new HG R&R, hoses, serpentine, waterpump, (20) Timeserts & drilling out block, etc. (Note: the Timeserts recommendation is a tested tip of what works, which is the whole purpose of this non-“official GM verbiage” forum, as I understand it.)

4. HG replacement tips:
a) Best to drop the engine cradle, so a lift is pretty essential.
b) Use a guide for drilling out and setting the Timeserts.
c) When doing R&R on old style coolant engine, go ahead and switch to DexCool, to be done with the corrosion worries, mate.
d) Other goodies you probably will want to R&R: t-stat, water pump, plugs, wires, hoses, ____, because now is a good time to do it.

I tried to boil it down (no pun intended) to the bare essentials for coolant therapy. Please feel free to add/change any of it as you see fit.

cadillac 17
02-18-12, 01:00 PM
bbob, i read the entire post on this and there is alot of technical info. my 2003 deville has idiot lites or what you people say damped or electronic displays instead of mechanical guages. i beleive only in mechanical guages and every car i owned i installed them. i like auto meter. but this northstar engine is complex and i hate the sideways fwd. do you know what fittings or sender locations i can use for water temp and oil pressure on this engine. i would appreciate it very much. i joined this forum so i could get help, this deville is the most complex engineered vehicle i ever owned. i do alot of out of town driving and i hate idiot lites.

RippyPartsDept
02-18-12, 02:01 PM
I don't think bbob is active here anymore ... if you check the user profile it will tell you when the last post and last login to the site was ... i bet its a few years ago (at least!)

you'll probably get better responses starting your own thread

Submariner409
02-18-12, 05:37 PM
Practically no one who posted in this thread is still here.

The only way to go to either electrical or mechanical oil pressure is to fashion a T at the oil filter adapter. You need to retain the present pressure sensor/sender because it interacts with other car systems. The coolant temp is a real problem - there are NO unused block/water jacket fitting holes.

Oil pressure in these engines is seldom a problem and the above is the only way out. The present switch opens at 5 - 6 psi and sets a DIC message. Don't sweat it. (Yes, I grew up in MG, Austin Healey, Jaguar, Chevrolet - all with real gauges.)

For 12 other gauges that are already monitored in your car, take a look at a ScanGauge-II www.scangauge.com (http://www.scangauge.com). Very handy tool and you can mount it anywhere - mine is over the driver's sun visor - I monitor coolant temp, ignition advance, MAP, and intake air temp........or any of 8 other plus you can code several more yourself.

Actually, this thread is very instructional - it would do many of the newer members a lot of good to read the whole thing, and as you know, Chris, all of it has been re-posted a thousand times in answer to a thousand threads since 2007.

RippyPartsDept
02-18-12, 08:32 PM
yeah... all good info sub

c17 - basically the short answer is that if you can't drive a car without real gauges then you can't drive these cars ... try the performance versions though (concourse, sts, etc, dts, etc ... that have some gauges ... kind of a hybrid digital-analog cluster)