: Head Gasket Problem



skipper two
12-15-04, 09:17 AM
Newby here. Purchased used 2000 DHS with 41,000 miles. After about an additional 6000 miles started getting “Check Coolant Level” msg. Also, on occasion the engine startup would be rough for a few seconds then run smooth. Advised mechanic at normal oil change interval. Mechanic researched and diagnosed problem as head gasket. Advised repair could cost up to $2,500. Recommended tablets as interim fix and suggested probably better off trading in vehicle for something else. He dropped GM tablets into surge tank and worked fine for last 500 miles. After reading forum articles, understand tablets should have been inserted into hose. Should I obtain more tablets and insert in hose? Any idea how long the tablets are effective? Although I trust the mechanic with both of my vehicles, he has never performed a head gasket replacement on a Northstar engine and therefore estimated cost may be low. Any thoughts appreciated. Is there any chance it may be another problem other than the head gasket?

oldgamer
12-15-04, 04:19 PM
The tablets in a surge tank - bad idea. Just check if it still in a surge tank. May be it's possible to suck it from there.
Put them into the hose.
The tablets will work untill next coolant change.
And more: may be your car's fine. If I was you I think twice before doing head gasket.

caddywhizkid
12-15-04, 09:19 PM
Tablets go in surge tank. Putting them in the hose is absurd. I do agree with oldgamer about headgaskets though, make sure the mechanic is good, and ask him how he knows its the headgaskets.

BeelzeBob
12-15-04, 11:29 PM
Tablets go in surge tank. Putting them in the hose is absurd. I do agree with oldgamer about headgaskets though, make sure the mechanic is good, and ask him how he knows its the headgaskets.



Complete misinformation here.....

Tablets do NOT go into surge tank.


Putting the supplement into the Northstar surge tank directly is to be AVOIDED. At the very least it will be ineffective as it does not circulate thru the cooling sytem and will just lie in the surge tank. At the worst, putting 6 of the pellets into the surge tank has been known to clog the hose leading from the surge tank to the water pump inlet causing pump cavitation and overheating as a result.

ALWAYS PUT THE COOLANT SUPPLEMENT INTO ONE OF THE RADITOR HOSES OF A NORTHSTAR ENGINE.

By design the pressurized surge tank has very little bulk flow of the coolant. It serves as a pressure vessel at the high point in the system to pressurize the water pump inlet to prevent cavitation. There is very little flow thru the surge tank by desing so as to allow deareation of the coolant. Low flow means that the coolant supplement particles that are simply in suspension in the coolant can not be distributed thru the system to work effectively.

The coolant supplement ( as has been discussed many times on the forum) does not really dissolve in the coolant but the tiny fibers or particles of the supplement are carried in suspension thru the cooling system. If a large quantity of the supplement is introduced into the surge tank it will usually just settle to the floor of the surge tank. It can, before it gets dispersed, clog the hose to the water pump and block the feed from the surge tank causing pump cavitation and overheating symptoms.

Best to pop a hose off, put the supplement in and replace the hose. That way the supplement is installed into the bulk flow path of the cooling sytem where it can be dispersed rapidly and effectively. That is where the factory installs it originally.

peteski
12-16-04, 01:57 AM
Looks like caddywhizkid is not *the* Northstar master after all...
:D

Peteski

skipper two
12-16-04, 09:56 AM
Thanks everyone for your inputs. A special thanks to bbobynski for his obviously professional understanding of the system. Will do as he recommends and hopefully will solve the problem until next coolant change.

caddywhizkid
12-16-04, 07:31 PM
Ok I was wrong about the tablets. I looked it up and was wrong. Although I personally have never heard of any adverse affects when put into the tank. Also just because GM says it, it dosen't mean its right. 150000 miles before Dexcool flush, or 100k before trans service. GM say that but I know alot of people who don't agree. As far as I'm concerned you shouldn't have to add pellets, N*'s are in in 45000$ + cars that shouldn't need them. This is a bandaid for poor quality control.

Spyder
12-16-04, 08:10 PM
uh oh...Bbob's not gonna like that one... *snicker*

BeelzeBob
12-16-04, 08:30 PM
Ok I was wrong about the tablets. I looked it up and was wrong. Although I personally have never heard of any adverse affects when put into the tank. Also just because GM says it, it dosen't mean its right. 150000 miles before Dexcool flush, or 100k before trans service. GM say that but I know alot of people who don't agree. As far as I'm concerned you shouldn't have to add pellets, N*'s are in in 45000$ + cars that shouldn't need them. This is a bandaid for poor quality control.


LOL LOL LOL

I guess that is why nuclear subs use the sealer in their cooling systems....LOL...lack of quality control. One of the largest accounts that the company that makes the coolant supplement has is the US Navy.

All of the coolant supplement is made by the same company in Holly, Michigan. They also hold the copywrite on the BarsLeaks brand and sell the product under that name.

In a perfect world, I would agree with you. And the fact is that most of the engines do not need the sealant. There are occasional porosities in aluminum castings, scratches in gasket surfaces, etc. that the coolant sealer guards against. It is just insurance against incidental leaks. It is not something that is mandatory to making the engine live longer...i..e...it does not "condition" the coolant or add corrosion protection, etc. It just guards against casual leaks that might occur in the cooling system that is especially common in all aluminum engines due to the propensity of aluminum castings to have porosity that often doesn't show up until after the part has been thermocycled many times.

The fact is that almost every automaker in the world uses the coolant supplement/sealer installed at the factory for the very same reason.

The sealer is mandatory in the 4.1/4.5/4.9 engines to guard against coolant intrusion into the oil. The Northstar cannot reasonably leak coolant into the oil (which is why blown head gaskets rarely if ever end up with coolant in the oil in a Northstar) due to it's design but the 4.1/4.5/4.9 engine can so the coolant supplement IS vital to the long term health of the engine.

dkozloski
12-17-04, 04:10 PM
The story about stop-leak in the submarine nuclear reactor stems from bad welds in the stainless tubing in the reactor of the first nukey boat, the Nautilus. The welds had hairline cracks that were deemed to be not dangerous so members of the crew were sent ashore to all the auto stores around to buy stop-leak as a temporary measure. Since that time repairs have been made and procedures changed to improve the welding process and the stop leak is no longer used. It is a good "sea story" with a thread of truth through it. You'll find details in the book "Nautilus 90 North".

BeelzeBob
12-17-04, 09:52 PM
The story about stop-leak in the submarine nuclear reactor stems from bad welds in the stainless tubing in the reactor of the first nukey boat, the Nautilus. The welds had hairline cracks that were deemed to be not dangerous so members of the crew were sent ashore to all the auto stores around to buy stop-leak as a temporary measure. Since that time repairs have been made and procedures changed to improve the welding process and the stop leak is no longer used. It is a good "sea story" with a thread of truth through it. You'll find details in the book "Nautilus 90 North".


Good reference...wonder what the Navy is doing with all that BarsLeak then....LOL.... Last time I checked (admittedly several years ago) they were still buying the stuff ....

caddywhizkid
12-18-04, 12:24 AM
Probably selling it to cadillac so they can sell it as gm stuff for their piss-poor northstar engines.

dkozloski
12-18-04, 12:29 AM
I wouldn't be surprised if the navy had nukey subs carrying BarsLeak around for emergencies. It worked the first time. If I remember right they bought all the BarsLeak in Seattle and the Pacific Northwest.

BeelzeBob
12-18-04, 05:21 AM
Probably selling it to cadillac so they can sell it as gm stuff for their piss-poor northstar engines.


It always astounds me how techs bad mouth something that is putting food on the table.... If it weren't for the "piss-poor" Northstar they wouldn't need you to work on them and you wouldn't have a job....LOL LOL... Like I said in another post. There are several million of them running around that don't have a problem in the world. You see ones that have a problem and assume that they all are that way. It just isn't the case.

ellives
12-18-04, 07:33 AM
Probably selling it to cadillac so they can sell it as gm stuff for their piss-poor northstar engines.


Anybody know where the "ignore" button is on this forum?

dkozloski
12-18-04, 03:28 PM
Hire'em young while they still know everything.

ellives
12-18-04, 03:37 PM
Hire'em young while they still know everything.

I was young once and knew everything. Now I know so much more but realize how little I really know. Kinda makes me wonder if I'll ever see a doctor again. Know what I mean?

Ells

peteski
12-21-04, 03:41 AM
Probably selling it to cadillac so they can sell it as gm stuff for their piss-poor northstar engines.

Hey, if you really are a Cadillac mechanic an an expert, you must really hate your job! All you do at work all day is to fix those piss-poor GM made Caddies.

If you were badmouthing GM like this in the shop, I would never have you work on my car.

Now where is that left-handed attitude adjustment wrench... Hmmm.
I think I lent it out to someone few months back...

:hmm:

Peteski

MH99CADEDO
12-21-04, 09:13 AM
You don't have to be an expert to be a lot boy at the Cadillac dealership.

Fiero STS
12-21-04, 09:43 AM
Probably selling it to cadillac so they can sell it as gm stuff for their piss-poor northstar engines.
It is the same with any dealership. In the service dept., you only see the bad cars. Auto makers produce tens of thousands of cars/engines a year so if a dealer sees 100 bad cars this is a very small percentage of the total number out there. When was the last time someone made an appointment to bring in his 250,000 mile N* car to say Gee Whiz this thing runs great and I didn't have any problems.
Another problem is preconcieved problems. If someone brings in an N* with an overheat problem, the service manager assumes it's a head gasket, as he " knows " this is a common problem associated with overheating. After the engine is torn apart and head gaskets replaced, they find a bad thermostat, " that was probably caused by a bad head gasket ", but in truth was the root cause of the problem. I work for a Caterpillar dealership, Everybody knows cat quality is legendary, but we too wonder how Cat can stay in business with all the problems we see. Truth be told we see a small amount of repairs for the number of hours these machines run. Some machines get 8000 plus hrs a year running 24/7.

oldgamer
12-21-04, 10:06 AM
Exactly.
I think, that 85% of problem with cars are misdiagnosed. Very often, if not all the times mechanics follow their "feel" and change good part because of their experience. If it not helps they change something else and in most cases don't put old part back (it's cost money to put it back at first, and second what if that part has intermittent problem?). Often it is hard to say what cause of problem after all. To get true statistic all problems should be analyzed in a factory laboratory. Otherwize it is not a statistic, just a rumor.

caddywhizkid
12-21-04, 05:36 PM
In just my dealer we see at least 100 major caddy repairs a year, now just imagine how many dealers are out there some I'm sure doing alot more some a lot less. My point is my dealer is only one and we see alot of major repairs, i can only assume the thousands of other caddy dealers are seeing alot of major engine repair as well. Doesn't seem like such a small percentage then does it?

BTW If I'm a lotboy then I must be this highest paid lotboy in the country.

caddywhizkid
12-21-04, 05:44 PM
I almost forgot right now I have a N* ripped down to the bareblock. I'm replacing the piston rings for high oil consumption. Also pulled a bent rod out of this motor. 40k miles on it. Also we already did GMs first bandaid fix for this, the carbon treatment. The car is an 02 btw. Now before you all say its probably me playing up the problem, this is the customer complaining, and I agree. No car should burn oil at 40k. I know this is just one car but how many you think have been done at the thousands of other dealers this year?

Spyder
12-21-04, 09:05 PM
How much oil is it "burning"? Or is it the standard oil consumption that is expected from these motors and many others from many other brands?

Ranger
12-21-04, 09:07 PM
How much oil is this car burning?

ellives
12-22-04, 11:06 AM
I almost forgot right now I have a N* ripped down to the bareblock. I'm replacing the piston rings for high oil consumption. Also pulled a bent rod out of this motor. 40k miles on it. Also we already did GMs first bandaid fix for this, the carbon treatment. The car is an 02 btw. Now before you all say its probably me playing up the problem, this is the customer complaining, and I agree. No car should burn oil at 40k. I know this is just one car but how many you think have been done at the thousands of other dealers this year?

I've actually wondered what the actual cause and solution for the high oil consumption is if the initial carbon treatment does not work. Are you saying the rings have gone bad? Is there any visually notable problem with the rings? Is there anything else you are doing to combustion chamber components as part of the work?

Ells

dkozloski
12-22-04, 04:28 PM
The way it was explained to me, the breakin process for piston rings and cylinders is essentially a race. On the one hand the rings must wear to conform to the cylinder walls; on the other hand the honing marks on the cylinders are filling with varnish from scorched oil. If the rings win you have a good engine, if the varnish slicks up the cylinders first, the rings never will seal up. Some of the variables involved are, cylinder finish i.e. the honing job, ring material i.e. chrome, moly, or plain cast iron, and how hard the engine is operated early in life. Our process that we used to breakin aircraft engines was to run the absolute minimum in the test cell to make sure there were no leaks or blunders. Get the engine running at least 75% max power until you see the cylinder head temperature take a sharp drop which would take less than 30 minutes. The high power setting makes sure that there is plenty of gas pressure behind the rings to make sure they breakin quickly. Automobile ring makers instruct you to do up to ten 30 - 60 MPH runs in high gear at WOT to accomplish the same thing. We used to tow our cars with HO engines to the start of the Parks Highway which leaves the town of Ester, AK. with a long steep hill. We would run it through the gears til we got to about 120MPH in high gear a couple of times. We never had ring seating problems. Chrome plating is used as a ring finish for long life but breakin can be iffy. Molybdenum is very soft for near instantaneous breakin but rapidly work hardens to a very long lasting surface. The honing process is much like alchemy. Some people advocate a rough finish, others want a finer surface, and others favor a combination. I remember reading years ago where ring companies were getting rings to seal so well that they were putting vacuum pumps on the crankcase to reduce aerodynamic drag on the rods and crank. Great leaps forward have been made in the ring and cylinder area to where a quart in 1000 miles is considered excessive. A quart/700 used to be the attention getting point.

BeelzeBob
12-22-04, 10:56 PM
Two important things about ring seating....

One...the most important area for the rings to "seat" against is not the cylinder wall but the sides of the piston grooves. It is imperative that the rings mate to the sides of the piston ring grooves as leakage in that area is one of the main sources of blow by past the rings.

The rings seal to the cylinder walls with the oil on the walls so there is very little additional sealing obtained with the rings against the walls.

Crosshatching is required to support an oil film on the walls to lubricate the upper rings adequately.

The rings do very little to no actual "break in" to the cylinder walls themselves believe it or not.... Take a brand new set of rings, run them in an engine for "break in" and then take them out and look at them under a microscope. They look the same..... In fact, the working edge of the rings look the same 50K miles later....there is very little to no wear or breakin to the working edge of the rings.

The surface of the cylinder wall is "broken in" by the rings passing over it. Any high spots (we are talking microscopic surface irregularities here) from the machinging and honing process are wiped off by the rings that does help the ring seal as the surface irregularities can upset the ring contact with the cylinder walls. Removing them is an important part of the "break in" process. But it happen within the first few miles of operation primarily.

If you ever assemble a brand new engine take the time to spin the crank over 20 or 30 times with the pistons in place and then look at the gray "pus" at the bottom of the cylinder walls. That is cast iron wiped off the walls of the cylinders. Even with that few revolutions you can see the surface asperities being wiped off the walls by the rings.

Two....rings constantly rotate and move on the pistons. The idea that the rings break-in to a certain spot on the cylinders and stay there is not correct. At high engine speeds the rings actually rotate on the piston constantly. I have seen studies where a radioactive tracer was put on the upper rings allowing the location of the tracer to be measured as the piston moved up and down the bore. The rings actually rotated at several RPM at high engine speeds.!!! So, any given part of the ring will contact any and all parts of the cylinder walls. This movement is good and is the reason you want to subject the engine to some frequent WOT and higher RPM....keeps the rings exercised and free in the piston grooves.

The 2000 and later Northstar engines have pistons with hard anodized top ring lands. This is a hard coating on the piston ring lands to improve wear and prevent poundout. This is good...but it is harder to seat the rings against the hard anodized ring grooves. If the hard anodizing left any surface irrigularities (microscopic) the ring has to pound it down to seat completely. Those engines absolutely need the full throttle load and WOT to seat the rings against the piston ring lands. The more the better.


The service ring pack for high oil consumption engines is simply a higher tension ring set....the rings have a larger "free" diameter so it takes more force to compress them to stuff the piston into the bore....so the rings press against the cylinder walls more firmly. Costs a little power and fuel economy due to more friction...but the increased tension will overcome any unusual cylinder bore roundness issues, any deposits in the piston ring lands and will exert more side load against the piston ring lands during operation to improve breakin against the ring lands. The increased ring tension also wears the rings faster....but the difference in service life is basically negligable.

BeelzeBob
12-22-04, 11:02 PM
I almost forgot right now I have a N* ripped down to the bareblock. I'm replacing the piston rings for high oil consumption. Also pulled a bent rod out of this motor. 40k miles on it. Also we already did GMs first bandaid fix for this, the carbon treatment. The car is an 02 btw. Now before you all say its probably me playing up the problem, this is the customer complaining, and I agree. No car should burn oil at 40k. I know this is just one car but how many you think have been done at the thousands of other dealers this year?



The "bandaid" works sometimes if the customer is a very gentle driver and the ring lands have carboned up restricting the ring motion..... It is not a cureall. When it works it works well due to deposit removal. In my opinion, it is often applied to the wrong cases as it is assumed to be a cureall for all situtions.

Bent rod, huh....LOL. Wonder what tech did the deep carbon cleaning on the engine that you mentioned..??? Sounds like they didn't get all the solvent out of the cylinder before cranking and hydrostatically locked a cylinder briefly and bent a rod. No other way to bend a rod, actually, and I can assure you it was not "bent" at the factory...LOL That is the down side to the "deep carbon cleaning." We frequently see "bent rods" due to the techs using improper "deep carbon cleaning" techniques. Seems the step of sucking out the solvent after the soak is often bypassed in haste to beat the clock or ????? Of course, GM covers it under "warranty" despite the fact that it was an error during the procedure. Done correctly the procedure will not damage a rod.

Ranger
12-22-04, 11:32 PM
Two....rings constantly rotate and move on the pistons. The idea that the rings break-in to a certain spot on the cylinders and stay there is not correct. At high engine speeds the rings actually rotate on the piston constantly. I have seen studies where a radioactive tracer was put on the upper rings allowing the location of the tracer to be measured as the piston moved up and down the bore. The rings actually rotated at several RPM at high engine speeds.!!!
I have always been of the understanding that when installing rings you staggered the gaps 180 degrees. What is the purpose of this if they rotate, or is that "old school"?

Spyder
12-23-04, 01:37 AM
and...what would happen if, in the rotating of the rings, the gaps all coincidentally ended up lined up, giving a big gap...I'm guessing they'd probably move right along and disperse themselves around the piston again, so it wouldn't matter for more than a few rpms?

dkozloski
12-23-04, 11:09 AM
Phillip Vincent of Vincent motorcycle fame claims that the rings can rotate at up to 60 RPM on the piston. They actually used a magnetic pickup and a miniature FM telemetry transmitter under the head of the piston to measure it. Most heavy duty diesel engines and some aircraft engines have a cast in circular steel insert in the piston for the rings to ride in. Some manufacturers have regressed from forged to cast pistons just to incorporate this feature. I used to hear a lot of stories about ring gaps being lined up and causing a score in the cylinder but my observation is that the score was there first and caught the ring gap coming around. Many times I removed an aircraft cylinder to touch up a valve seat or for inspection and replaced it with the same rings with no trouble at all. The USAF claims that compression TEST pressures get down to about 50% of nominal before you get a noticable decrease in power. The worst oil burning aircraft engines I saw had more ring groove wear than anything else. The ring grooves could become so worn that the rings would hammer the sides of the groove enough to extrude metal from the piston and leave a sharp ridge. Eventually the rings would fatigue and break. Most experts agree that ring, piston, and cylinder wear come from the ingestion of dirt and the great leap forward in engine life has been the paper air filter cartridge. Franklin engines had a cast iron sleeve and if new rings were used in worn pistons the rings would tip in the grooves and shave metal from the sleeves and you would find the sparkplugs packed with shavings. Oil rings with expanders don't seem to rotate like the others so with horizontally opposed engines we would put the gaps to the top so if the machine was parked on a side hill there was less chance of the oil running into the combustion chamber. Other than that the gaps were just staggered.

caddywhizkid
12-23-04, 08:08 PM
I'm not sure on the exact amount of oil being burnt, but I do know my boss is very strict with the chart to monitor how much oil is added and burned in the engine and we wouldn't have done this much work if it was within guidelines.

As far as any ring problems. I didn't see anything except some carbon on some of the oil rings, altough some of them were almost seized into the pistons.

I have to agree Bbob, I think the wot treatment will work wonders. The problem is, most of the cars we see never will see anywhere near wot. Also I agree the carbon treatment isn't a cureall but GM thinks it is. Any time oil consumption is mentioned, carbon treatment is always the first step (providing the chart was done to determine if its past GM guidelines). Rings are only last resort, unfortunatley we have done three of these ring jobs in the past three months.

caddywhizkid
12-23-04, 08:10 PM
The service ring pack is a higher tension ring, but it also now uses a steped #2 compression ring.

BeelzeBob
12-26-04, 07:47 PM
The service ring pack is a higher tension ring, but it also now uses a steped #2 compression ring.


Just general info....the original OEM ring pack in the 93/94/95 Northstar engines used a dyke land ring or step land ring as described for the second compression ring. The step land ring was revised to a barrel faced ring for less friction/better compression seal in later model engines..... The second ring does a great deal of the oil control (as well as sealing compression blowby from the first/top ring) but testing indicated that the stepped ring was not required.....so it was eliminated as experience was gained with the engine in the field. 93/94/59 engines used very little oil generally (well within reason considering the rather aggressive honing pattern) and practical experience seemed to indicate the stepped ring was not contributing that much more to oil economy.

A stepped second ring is considered a very "aggressive" oil control technique so that is one reason the service ring pack helps to "dry up" oil consuming engines.

blb
12-27-04, 07:08 PM
I'd be interested to hear bbob's thoughts on why the headgaskets are failing on Northstar's, less that 5 years old with under 100,000 miles, since the usual excuse of inadequate cooling system maintenance can't be used in those cases.

Also, I think GM does a disservice to the orgainization when it provides the higher ranking engineers and managers with the free use of new GM vehicles, and replaces them every 6 months to a year. Its easy to say a headgasket problem is no big deal when you're not the guy who either has to shell out big bucks for the repair, or spend many hours of your own time turning bolts. Because of this, the bad engineering decisions and cost-cutting programs directly responsible for poor quality tend to be repeated time and again.

For example, someone needs to explain to me why GM would design an engine that absolutely needs many WOT runs to keep it running right and not burn oil, (according to bbob), and it is primarily used in vehicles that are least likely to be driven hard based on the demographic profile of the majority of current owners. This kind of poor engineering and decision making is why GM's market share continues to erode every year. Senoir citizens don't want to be told that it's their fault their cars burn oil because they don't floor them enough. I hope GM can turn things around, because they do make some vehicles that are fun to drive, but based on the nagging quality issues, you really don't want to own one, long term.

To say that the dealerships should be glad for these quality issues because it gives them job security may be true for the short term, but in the long term, market share will continue to be lost.

oldgamer
12-28-04, 10:17 AM
Couple month already I still can't find place to WOT. Unfortunately I use my caddy in urban area of NYC, stop and go (the worst scenario to the engine), not really the best place to WOT. If I put my foot a little harder then usual my wife gets scared easy. Car jumps like a rocket if I WOT, so I should planning WOT, let say for trip to my sister's using NJ Turnpike. And if I go to my sisters I have my wife, 75 years old mom, 91 years old stepfather and my sister's mother in low (76 years old). Not the best company to making WOT. So, it's really impossible to make a WOT. :crying: Like some people say: "You chose wrong car. You should have a Honda Civic - it's easy to park in a city."

Talking about oil consumption, I can say that my Northstar doesn't eat oil at all. And anyway oil eating is not a big deal I think. It should not bother.
Still interesting to hear from bbobinsky :yup:

ellives
12-28-04, 12:26 PM
I'd be interested to hear bbob's thoughts on why the headgaskets are failing on Northstar's, less that 5 years old with under 100,000 miles, since the usual excuse of inadequate cooling system maintenance can't be used in those cases.

Also, I think GM does a disservice to the orgainization when it provides the higher ranking engineers and managers with the free use of new GM vehicles, and replaces them every 6 months to a year. Its easy to say a headgasket problem is no big deal when you're not the guy who either has to shell out big bucks for the repair, or spend many hours of your own time turning bolts. Because of this, the bad engineering decisions and cost-cutting programs directly responsible for poor quality tend to be repeated time and again.

For example, someone needs to explain to me why GM would design an engine that absolutely needs many WOT runs to keep it running right and not burn oil, (according to bbob), and it is primarily used in vehicles that are least likely to be driven hard based on the demographic profile of the majority of current owners. This kind of poor engineering and decision making is why GM's market share continues to erode every year. Senoir citizens don't want to be told that it's their fault their cars burn oil because they don't floor them enough. I hope GM can turn things around, because they do make some vehicles that are fun to drive, but based on the nagging quality issues, you really don't want to own one, long term.

To say that the dealerships should be glad for these quality issues because it gives them job security may be true for the short term, but in the long term, market share will continue to be lost.


While BLB takes an unnecessarily (to my mind) adversarial approach to asking the question (a second time in fact) it would be good to keep the dialog going. It's interesting in Oldgamer's post just prior to this one he isn't having oil consumption problems. My '96 has had it since I bought the car with ~20K miles on it. I wish now in hindshight that I'd complained to the dealer about it when it was under warrantee and they would have corrected the problem. All said though, the oil consumption itself hasn't been a huge hindrance.

Ells

blb
12-28-04, 03:41 PM
The lack of a response comfirms what most of us suspect.

Spyder
12-28-04, 06:00 PM
The lack of a response?!?! You should give him more than 21 hours to respond. Not everyone one here can be active in the forum every minute of their waking lives. You posted a question at 7 o clock yesterday, now at 3 today, you take the lack of a response as a "confirmation" of what "most of us suspect."? Alrighty then... ... ...

blb
12-28-04, 06:50 PM
Spyder....Relax. The first two paragraphs of my thread above are exactly the same as posted on 12-19-04 on page 3 of the thread entitled " What makes the Headgaskets go so often on early N*s", and there has been no response to the exact same question on that thread either. Those that have been following the recent headgasket threads are aware of this.

BeelzeBob
12-29-04, 06:37 AM
The lack of a response comfirms what most of us suspect.


Not sure what you are expecting.... Obviously, with a question and a comment like that you have a hidden agenda that no answer is likely to satisfy.

BTW...what is it you "suspect"...???

As far as my "adversarial approach" to answering questions....I appoligize for not BS'ing around and not beating around the bush. If my rather direct answers and comments offend you then just don't read my posts. I try to give direct and factual information to the best of my knowlege and present both sides of the issue from what I know about it.

In my experience the number of failed head gaskets on cars that are less than 5 years old and under 100K are pretty small. Not sure what causes them without examining each one. There are a LOT of Northstar engines in the field and the vast majority of them do not have a head gasket problem at all...ever...

Similarily with the oil consumption and WOT. The engine is not "designed to require WOT". The difficulty in designing an engine like the Northstar is the extreme variety of duty cycles the engine will see. The engine is a small displacement engine to maximize the fuel economy potential of the package and has very high specific output to provide the vehicle performance required. Certain lubrication requirements must provided for the top rings and such so the engine can live under extended full throttle operation at max output (autobahn driving) which are not necessarily conducive to optimum oil economy idling in NYC traffic on a daily basis.

My point in mentioning the WOT operation on the forum is to provide an alternative to invasive de-carb procedures and information so that those interested in following the advice can have an engine that performs to it's maximum potential and avoid any unecessary service or annoying noises.

Regarding the oil consumption, the Northstar is not alone in this issue. Every other manufacturer of high out put engines has similar issues trying to balance the requirements of oil consumption and lubrication requirements during high speed operation and constant city driving. Mercedes, BMW, Toyota, etc... all have similar guidelines published indicating that even 1000 miles per quart is "acceptable" oil consumption and does not indicate anything wrong with the engine. BMW went so far on some of its recent M series engines to state in the owners manual to check the oil on every tankful of gas as oil consumption might be sufficient so as to reach the point of low oil level starvation and engine damage within two tankfuls of fuel in autobahn type driving. Do a little reading on other manufacturer sites and you will find the same thing that I have found.

ellives
12-29-04, 07:42 AM
Not sure what you are expecting.... Obviously, with a question and a comment like that you have a hidden agenda that no answer is likely to satisfy.

BTW...what is it you "suspect"...???

As far as my "adversarial approach" to answering questions....I appoligize for not BS'ing around and not beating around the bush. If my rather direct answers and comments offend you then just don't read my posts. I try to give direct and factual information to the best of my knowlege and present both sides of the issue from what I know about it.

In my experience the number of failed head gaskets on cars that are less than 5 years old and under 100K are pretty small. Not sure what causes them without examining each one. There are a LOT of Northstar engines in the field and the vast majority of them do not have a head gasket problem at all...ever...

Similarily with the oil consumption and WOT. The engine is not "designed to require WOT". The difficulty in designing an engine like the Northstar is the extreme variety of duty cycles the engine will see. The engine is a small displacement engine to maximize the fuel economy potential of the package and has very high specific output to provide the vehicle performance required. Certain lubrication requirements must provided for the top rings and such so the engine can live under extended full throttle operation at max output (autobahn driving) which are not necessarily conducive to optimum oil economy idling in NYC traffic on a daily basis.

My point in mentioning the WOT operation on the forum is to provide an alternative to invasive de-carb procedures and information so that those interested in following the advice can have an engine that performs to it's maximum potential and avoid any unecessary service or annoying noises.

Regarding the oil consumption, the Northstar is not alone in this issue. Every other manufacturer of high out put engines has similar issues trying to balance the requirements of oil consumption and lubrication requirements during high speed operation and constant city driving. Mercedes, BMW, Toyota, etc... all have similar guidelines published indicating that even 1000 miles per quart is "acceptable" oil consumption and does not indicate anything wrong with the engine. BMW went so far on some of its recent M series engines to state in the owners manual to check the oil on every tankful of gas as oil consumption might be sufficient so as to reach the point of low oil level starvation and engine damage within two tankfuls of fuel in autobahn type driving. Do a little reading on other manufacturer sites and you will find the same thing that I have found.


BBob - I think the reference to "adversarial approach" was attributable to me and if so I'd ask you to re-read my post and you'll notice I was referring to BLB and not you. Sorry for the confusion.

Ells

dkozloski
12-29-04, 11:15 AM
bbob, I don't think the average bear realizes the minute quanities of oil we are talking about here. I was told by a TCM engineer that if each cylinder comsumes a dime sized spot of oil 0.0001in. thick with each revolution, it will be a smoker and burn a quart of oil/100 miles. It's obvious these guys never experienced life before plated rings and valve stem seals. This is like complaining that the miracle you got was not quite up to your expectations. I had a Mazda RX-7 Turbo that injected oil with a pump like a two-stroke to lubricate the rotor seals and used a quart of oil in 700 miles when new. Some of these people would be out in front of that dealership hanging the owner in effigy. If I was so poor and infirm that I couldn't pour a quart of oil in my car every 1000 miles I think I would just wander out on the ice flows and freeze to death.

blb
12-29-04, 03:31 PM
bbob...thanks for your reply...and BTW I appreciate your direct style in answering questions for us...it was another board member that was accusing ME of being "adversarial" (although that was not my intention), not you. As far as what we are expecting, I was hoping you could tell us that there was some kind of project underway to improve the attachment of the heads to the block on the Northstar to prevent the small percentage of headgasket failures. This would make a good product even better. I was hoping that I wouldn't hear that the problem only affects a small percentage of the vehicles, and this failure rate is considered acceptable by GM. I have to ask if GM even keeps records and has data on the number of headgasket repairs done by dealers on cars out of warranty. I am used to a culture where constant improvement is the price of admission to participate. Even though only a small percentage exhibit this headgasket issue, a small percentage is still considered too many, in many cultures. I want to add that I have not had this problem with my meticulously maintained 10 year old Northstar, and I have no hidden agenda. I do know of two other people (one relative and one co-worker) who had Northstar headgasket issues before the first scheduled coolant change on newer Northstars, and GM would do nothing to help with the repair cost since the vehicles were out of warranty. As you might expect, these people are done with Cadillacs forever and I will not buy another until I hear that GM is addressing this issue in some way. Again, I do appreciate and thank you for your comments and insight.

BeelzeBob
12-29-04, 09:35 PM
As I mentioned in several other posts there have been detail changes in the head bolt interface area on the Northstar engine over the years. Certainly I, and the other engineers that work on the engine, understand "on going improvements"....

Metallurgy in the head bolt hole area, processing of the head bolt hole tapping/threading operations, length of thread in head bolt holes, length of head bolts and head bolt thread engagement, etc.. have all been "adjusted" over the years of production to enhance the head bolt hole integrity.

When the engine was redesigned for the 2004 rear wheel drive applications the head bolt design was changed from a 1.5mm pitch thread to a much stronger 2.0mm pitch design. The 2.0 pitch thread is a bit unconventional in terms of typical thread pitch for that diameter bolt but testing has proven it to be stronger and have better thread engagement as the clamp load changes during thermalcycling "working" the joint.

There have been a number of other gasketing and fastening designs considered and tested for the head gasket joint with limited to no success. The head gasket in an all aluminum engine is a highly stressed item. It is difficult to seal and the design currently employed continues to work better than other designs considered and tested. Needless to say, testing of potential design changes in this area takes a great deal of time and even if a design shows potential in the lab it will often not pan out when tested in dyno and thermocycling engines and in test fleet engines.

The head gasket joint in the engine was one of the most thoroughtly tested areas of the engine when it was developed in the late 80's and early 90's. Since then, several factors enter into the equation. One is father time. We couldn't test head bolts that had been installed for 12 or 13 years without being disturbed to see the effect of simply removing them on the thread integrity in the block. Another is the fact that the engine, transmission and cars are giving such excellent service that they are far out living most people's expectations of 12 and 13 year old cars.


All in all, the head gasket in the Northstar holds up reasonable well for an all aluminum engine. As I have stated before, the engine is becoming it's worst enemy. It use do be rare to run cars past 100K and if they were over 100K the bodies and interiors were scrap and engines rarely were the life limiting item in the car. Most of the cars discussed on this forum are well over 100K with many at 150K and 200K. Everyday a new poster shows up having bought a "mint" early 90's FWD Cadillac. This would NEVER have been the case 20 years ago. Sooner or later in an all aluminum engine something is going to start to fatigue and require maintenance. About the only internal item on the Northstar seems to be the head gasket joint. And that joint is easily repairable...the major problem seems to be education of how to do it correctly. Education , by the way, that was published in the first Northstar service manual for the 1993 Allante....

As with all mechanical devices, there is always room for improvement. The desireablity of a 200K or 20 year head gasket joint with 100% reliability is well known and understood in the engine engineering community...LOL.


Similarily with the oil consumption, there is greater understanding of how the engine is being used and what the expectations are. Quit frankly, there are a number of engineers that are surprised at the hue and cry over oil consumption. Oil consumption is just a fact of life with high output engines. Same at BMW, Merc, etc..... The public seems to equate oil consumption with something wrong or bad or failing. It just isn't. But, having learned this, oil consumption has been addressed and reduced considerably.

One thing that makes oil consumption more obvious is the dramatically extended change intervals on modern engines. When oil was changed every 2000 miles using a quart or two was not noticed...particularily on an engine with 7 quarts in the sump. With 12,500 change intervals per the oil life monitor on certain Northstars, having to add oil suddenly becomes very obvious. The number of people that remember having to add oil or change oil every 2000 or 3000 miles must be diminishing rapidly....LOL

When the engine was being designed and developed, the real concern and emphasis was making sure the engine lived under heavy duty use. There was a great deal of full throttle testing...i.e...300 hour WOT endurance runs at 6000 RPM on the dyno were and are a standard part of the Northstar validation testing. The public was crying for performance and we assumed that the public would use the power..... Seems odd to us to have to beg people to hold the friggin throttle wide open on accels....LOL. Interestingly, cold carbon rap, oil consumption, ring sealing, etc... was never seen on any of our engineering fleets nor on development team members personal cars.

RLLOVETT
12-30-04, 10:40 AM
For me, the earlier post rings a bell: Why did Caddy develop a high performance engine that would maintain oil supply at high rpms through extreme cornering and benefit from judicious WOT runs for a market that hasn't EVER felt the rug under their right forefoot?! I've always felt a mild kinship with people that own the same car as me so I check out the fellow Eldo/STS/SLS owners on the road...by my tally, 75 percent of them are female with blue hair and glasses. Don't get me wrong, I love my Eldo, most especially it's 'stealth' quality--I've had more fun than I really should be allowed blowing away the MBs/Beamers/TTs who thought they were dragging an old folks car and forgot to put the hammer all the way down...

dkozloski
12-30-04, 10:41 AM
The head cylinder joint has always been a problem on all aluminum engines. The Rolls-Royce Merlin went so far as to eliminate the joint altogether by casting the head and cylinder block together and then bolting this assembly to a barrel crankcase. This was later reversed when it was found that the valves required work every 250 hrs. of operation. Allison fastened individual cylinders to the head, each with one big nut tightened to thousands of lbs. ft. torque. Offenhauser had the head and block cast together in the venerable old four cylinder that dominated Indy for twenty years or more. It looks to me that the North* is about the most successful all aluminum engine in history. You see a lot of attention paid to the head block joint on this forum but i'll bet that 99.9% of the owners over the years wouldn't have any acquaintance with the subject at all because they would never have encountered it. I think we are listening to a lot of people that are looking through the wrong end of the telescope.

blb
12-30-04, 01:02 PM
I'll throw this out for discussion.....The LS1 and the Northstar are both all aluminum, 8 cylinder, GM engines. (I happen to own one of each). I realize the similarities end there, but nonetheless, consider this:

The LS1's are put into Corvettes and F bodies that are, in many cases, thrashed repeatedly on the roads and at the track(especially in the case of the F bodys and young drivers) and there are hardly ever headgasket issues on those engines. In fact, the LS1 seems darn near bulletproof. The worst thing that seems to happen to the LS1 is bent pushrods from revving way past redline.

The Northstar is put into vehicles where the majority of owners rarely, if ever flog them, and the head gasket failures seem to be much more prevalent.

I don't know the specifics on differences in gaskets, bolts, torque specifications, mating surfaces, etc. between the two engines, but it would be interesting to be able to compare the two. I also know several people who have had their LS1s apart to upgrade them for higher performance applications and I have never heard of a need to timesert the tapped holes for the head bolts.

If anyone has any insight on this, it might make for an interesting discussion.

Ranger
12-30-04, 04:11 PM
I know Bbobynski doesn't like to hear this but I've said it before and I'll say it again. If they'd just quit trying to reinvent the wheel and stay with a tried and true cast Iron engine we probably would not be having this discussion. Yeah, I know, their heavier, but what's a couple of hundred pounds. The Northstar wouldn't even notice it.

dkozloski
12-30-04, 04:38 PM
Besides the cast iron engine was a great leap forward from the horse-drawn Zeppelin.

CAJUN-Z
12-31-04, 04:16 AM
All I can add to this is that I have a 2002 LS1 in the driveway (vette). It gets quite a bit of WOT operation and doesn't miss a lick. When I pulled the heads on the North* engine (it went into protection mode at highway speeds and spewed water out of the waterpump side of the front head), you could see the factory hatch marks on the cylinder walls on all the cylinders. The internals of the engine were flawless. I purchased the Deville with higher miles and it obviously had a hidden defect that was known by the previous owner (he traded it in to a Cadillac dealer on a new Deville). I called him after the headgasket failure and he told me of a history of overheating and service cycles to the local Caddy dealer. He didn't go as far as saying that the service department had prior knowledge of the head gasket failure (which showed-up after around 80 miles of me purchasing the vehicle from the dealership). We have a law in Louisiana that if there is a major hidden (concealed) defect that adversely affects the value of a purchased vehicle within a year...the seller is liable for repairs. I am looking in to this currently. The local Caddy dealer wouldn't release repair records on the Deville, but it may not matter since I contacted the previous owner. BTW, the Caddy dealer wanted $4500 for the headgasket repairs with timeserts. After the amount of work spent on this engine...I can see why the cost is so great for a head gasket job. Comments would be appriciated.... :banghead:

eldorado1
12-31-04, 12:57 PM
Yeah, I know, their heavier, but what's a couple of hundred pounds. The Northstar wouldn't even notice it.

You tack on a couple hundred pounds, and all of a sudden, all the aftermarket users (hotrods, sandrails, etc) will switch to LS1's. I'd bet you'd start getting complaints from the performance driven Caddy owners. "200 pounds!?! It's already a land-boat! I just lost two tenths in the quarter!"

Besides... who doesn't like to be on the bleeding edge of technology?

ZSKI
12-31-04, 08:54 PM
This discussion is compelling. I bought a 99 DeVille (45K) a year ago and I love it...absolutely LOVE IT! Well I have not had a head gasket problem yet...but lets just say I do run in to trouble some day. Just what and how are all of these people going about repairing these head gaskets? I am not sure how to ask this. Am I to understand that because of the posibility of having to TIMESERT that the engine needs to be pulled always? I can not help wondering...if the front head gasket were to blow, would it not be possible to replaced this front gasket only while the engine is still in the car? Do both head gaskets need to be replaced if one blows? Can you TIMESERT the front head while the engine is in the car? If this is not feasible and we are then forced to pull the engine is it then recommended to replace both head gaskets and to TIMESERT all twenty holes for both heads when doing a head gasket repair job? I guess what I am asking is...when/if I blow a head gasket, any head gasket, I can expect a good, qualified, knowledgeable repair shop to recommend what?

CAJUN-Z
01-03-05, 02:42 AM
Many mechanic shops I talked to wouldn't touch the north* engine! I was told by many that once was quite enough. Actually, you could do a lot of other more profitable mechanic work than work on a north* engine. It's very time consuming. I did mine without pulling the engine. Next time, I think it would be easier pulling the engine and doing everything on an engine stand. Sadly enough, the block must be time-serted (as I found out the hard way). The kit with inserts cost me about $375 . If you do it again, you have to use the "big-sert" kit which will set you back around $425. It's not a really fun engine to work on, but in hindsight, it's really not that bad. I knew nothing about the north* prior to coming to get info. off this site, and now I feel like I'm becoming an expert on the subject. All I can add is when the engine is together and running correctly, it really runs smooth and produces some real power above the 3700rpm range under wot. Extremely nice running engine....imo....

ZSKI
01-03-05, 06:02 PM
This discussion is compelling. I bought a 99 DeVille (45K) a year ago and I love it...absolutely LOVE IT! Well I have not had a head gasket problem yet...but lets just say I do run in to trouble some day. Just what and how are all of these people going about repairing these head gaskets? I am not sure how to ask this. Am I to understand that because of the posibility of having to TIMESERT that the engine needs to be pulled always? I can not help wondering...if the front head gasket were to blow, would it not be possible to replaced this front gasket only while the engine is still in the car? Do both head gaskets need to be replaced if one blows? Can you TIMESERT the front head while the engine is in the car? If this is not feasible and we are then forced to pull the engine is it then recommended to replace both head gaskets and to TIMESERT all twenty holes for both heads when doing a head gasket repair job? I guess what I am asking is...when/if I blow a head gasket, any head gasket, I can expect a good, qualified, knowledgeable repair shop to recommend what?

Never mind...I just found the thread ('Headgasket replace'), this answers ALL of my questions! Thanks.