99 Deville Northstar Overheat

[truant]

New info: GM document ID# 1559956 Headbolt Thread Repairs.

Summary: All head bolts should be inspected as they are removed for any aluminum threads on the bolt. If any aluminum is observed, the hole must be timeserted and all ajacent holes must be timeserted (so the holes to the left right and other side of the head too).

My warrantee co states in the contract that "only the damaged part" be replaced, and they interpret that as only the damaged hole. That's the party line. However they noted to me that if the factory recommends doing all of the holes, that the dealership can work that out with the adjuster, and that he'll probably make a concession to avoid possibility of a second tear-down.

Also, note that most warantee's limit of liability is the book value of the car. So if your warantee covers your engine, but a new engine costs more than the book value of the car.. you'll be getting either a used engine or a "sorry, we can't help you".

My car is being torn apart starting today. The service dept has been very helpful in assiting me with documenting the case before we get started with the R&R. Always ask for help and advice, it's free.

[JasonA]

We know from experience that even if a head bolt hole is not deemed "damaged", and one or more aren't Timeserted, it's almost a given that the repair will have to be made again.

Even if the warranty company will not reimburse you, I think I'd pay out of my own pocket the extra labor to Timesert ALL of the holes.

[zonie77]

jims 97 etc,

If you look at the design of the N* it uses free standing cylinders. That's where the different symptoms come from. Look at the article on timeserting a block and you will see the design of the block.

[Cadillac Jim]

zone77 & all -- the information here from truant and others is fascinating. Tying it all together in a particular scenario so that everything is simple and obvious is still to come. A scenario that I have observed repeatedly, and seen posted here about engines with head leakage:

Pulling on through a freeway ramp, outside temperature 25 F (-4 C), full-throttle acceleration to a high speed, up over a 3% grade that ends in a small overpass. The car coasts down to 70 mph or so. The temperature gage is steady at straight-up, the normal operating temperature. The downgrade ends and the throttle is gently adjusted to maintain about 70 mph. About a minute later, the temperature spikes, going in seconds all the way to the red zone. After about a mile, it slowly drops back to normal operating temperature.

Inside the engine with head leakage, during WOT acceleration we have combustion gases superheating a small amount of coolant, and the gas expands into the radiator and blows a couple of quarts out the overflow. A pocket of gas goes through the radiator and collects on the input side of the thermostat, isolating it. Heated water has not hit the temperature sensor yet; it's on the rear head on the driver's side, under the brake master cylinder power unit, possibly because that part of the water jacket in the head has steam in it instead of water. Hot water hits the temperature sensor (Engine Coolant Temperature, or ECT sensor) and the thermostat at about the same time, as the steam pocket gets past the thermostat and the hot water opens it, so that the water pump circulates the steam pockets out of the heads. The cooling system has overcome its steam thrombosis and takes hold again, but two to four quarts of coolant are lost through the overflow valve.

Anybody got a better model that explains everything?

[truant]

Hey everybody.

My right side (rear) head gasket failed on the passenger side of the engine, on the very end. A small chunk was missing and was likely chewed up by the water pump, or is still inside the cooling jacket.

10 of the head bolts were removed without having to break the static friction generated by torquing them down at install. The rest came out OK, meaning that when the tech went to remove them they made the satisfying “snap” of initially letting go of the block.

My dealership tells me they’ve done a lot of these, and even though no threads actually came out with the easy to remove bolts the block is no good and all of the bolts have to be timeserted. This we know from many many other posts.

The warrantee co refuses to pay for the timesert on ANY bolts because no threads from the block were visible on the bolts themselves.

There is much other evidence that I won’t go into right now on why the threads are no good.

Question is, can we measure the tolerances of the threads somehow to determine definitively that they are bad, because they didn’t shear off, they just mushed aside a bit.

I proposed measuring the depth of the hole, marking such depth on the bolt, and threading the bolt in by hand to see if it reaches that depth without encountering a change in the threads (which would make it hard to screw in).

[KHE]

Hey everybody.

My right side (rear) head gasket failed on the passenger side of the engine, on the very end. A small chunk was missing and was likely chewed up by the water pump, or is still inside the cooling jacket.

10 of the head bolts were removed without having to break the static friction generated by torquing them down at install. The rest came out OK, meaning that when the tech went to remove them they made the satisfying “snap” of initially letting go of the block.

My dealership tells me they’ve done a lot of these, and even though no threads actually came out with the easy to remove bolts the block is no good and all of the bolts have to be timeserted. This we know from many many other posts.

The warrantee co refuses to pay for the timesert on ANY bolts because no threads from the block were visible on the bolts themselves.

There is much other evidence that I won’t go into right now on why the threads are no good.

Question is, can we measure the tolerances of the threads somehow to determine definitively that they are bad, because they didn’t shear off, they just mushed aside a bit.

I proposed measuring the depth of the hole, marking such depth on the bolt, and threading the bolt in by hand to see if it reaches that depth without encountering a change in the threads (which would make it hard to screw in).

You will not be able to verify the thread integrity. Proper thread engagement is critical - if it were my car, I would just pay the parts and labor to have both sides (20 holes) Timeserted. The inserts are about $2.00 each and an expierenced tech. should be able to install them in two hours. Well worth the cost to assure you won't need to do the repair again. Make sure the tech uses the drill fixture so the inserts are installed at the proper depth to provide 100% thread engagement...

[truant]

This dealership is charging 2.88 for each tsert and 1/2hour labor to install each.

ouch.

Does anybody know the book time on it?

[RichieR]

I'm new to this forum, so I'm not 100% up to date on why there are so many head gasket failures with the Northstar Engine. Is there a flaw in the design of the engine, head gaskets, etc? Is there a GM bulletin on it? Do the head gaskets just blow over time for no reason (other than design flaw), or is it a result of improper maintenance, etc.?

Any detail will be appreciated.

[KHE]

This dealership is charging 2.88 for each tsert and 1/2hour labor to install each.

ouch.

Does anybody know the book time on it?

$2.88 sounds about right for the insert price but I think 1/2 hour per insert for installation is padded slightly. When I Timeserted the heads on my '97, I think it took me about 8 hours but it was the first time that I ever did the repair. A dealer should have more expierence - I KNOW I could install them faster if I ever had to do the job again on another car. Trust me - have them install the inserts and you won't have to worry about the job again.

I'm new to this forum, so I'm not 100% up to date on why there are so many head gasket failures with the Northstar Engine. Is there a flaw in the design of the engine, head gaskets, etc? Is there a GM bulletin on it? Do the head gaskets just blow over time for no reason (other than design flaw), or is it a result of improper maintenance, etc.?

Any detail will be appreciated.

There is no design failure - the number one cause of head gasket failure in the Northstar engine is improper cooling system maintenance. Headgasket failure is not as common as the internet forums would have you believe as most people visit a forum when they have a problem. For every problem you read about there are thousands of trouble free cars of the same model on the road.

[BodybyFisher]

Many have Northstars running over 200K miles with no problems. As you may or may not know, forums like this, tend to attract owners that have problems that they want to find out about or that they want to AIR out.. There are many happy NS owners driving around with NO problem...

If you maintain you coolant properly you will give youself a very good chance of success and having a high mileage engine. That means changing your coolant before 5 years/100,000 miles which ever occurs first, however more frequently if possible. Also utilize the cooling supplement everytime the cooling system is worked on. Change the thermostat everytime the engine overheats badly and at least every 2 years. Use OEM parts (water pumps, thermostats, hoses, radiators, etc). Keep the water pump belt and tensioner in good shape. Keep an eye on the cooling system for leaks, the radiator end tanks crack over time and leak pressure, you don't see leaks because the coolant vaporizes when it hits the air, make sure your radiator is good. Pay attention to your temps, normal temps range between 193 and 205 at 60, and 215 to 230 in heavy traffic..depending upon the season. In very hot weather greater than 95, I have seen 235 to 238 in heavy traffic, and I have learned NOT to panic...

The NS's built from 96 on have been delivered with Dexcool as Dexcool retains its corrosion protection longer and is easier on the water pump seal.

This is NOT a design deficiency however.

[Cadillac Jim]

I'm new to this forum, so I'm not 100% up to date on why there are so many head gasket failures with the Northstar Engine. Is there a flaw in the design of the engine, head gaskets, etc? Is there a GM bulletin on it? Do the head gaskets just blow over time for no reason (other than design flaw), or is it a result of improper maintenance, etc.?

Any detail will be appreciated.

Ritchie -- too many people aren't aware that the DexCool 5-year protection limit means that if you never change your coolant, it will eventually become corrosive and get into the head gasket and head bolt wells and threads. If your coolant hasn't been changed in 4 years, you should change it ASAP. Unless you flush it when you change it (and many don't want to introduce tap water into their system), the change will be less than complete and you should take this into account in figuring how long before you change it again. I have set a time of 3 years for DexCool for my cars and I recommned yearly for green anti-freeze.

I've had old coolant go corrosove both on my 1997 ETC and my wife's 1999 Grand Am GT. On my wife's low-mileage car, I changed the intake manifold gasket and water pump and solved that problem. On my high-mileage Northstar I decided that a new engine was the most economical long-term approach.

[Bill K]

I have to disagree that there wasnt a design flaw since the headbolts have been changed in 03 or so vehs.

No way can coolant cause the head bolts to pull and allow the gasses into the coolant.

Having had to change the head gaskets and seeing them as they were exposed when the head was lifted off it seemed pretty clear to the mechanic & myself that the deteruration was from the cylinder wall out. Not from the coolant in. It was also easy to see the coolant tabs deposits trying to fill the voids.

And yes, the coolant had been changed at 75K/4yrs w/tabs, by me.

[Cadillac Jim]

[With typos corrected by accepting word processor prompts]

I have to disagree that there wasn't a design flaw since the head bolts have been changed in 03 or so vehs.

No way can coolant cause the head bolts to pull and allow the gasses into the coolant.

Having had to change the head gaskets and seeing them as they were exposed when the head was lifted off it seemed pretty clear to the mechanic & myself that the deterioration was from the cylinder wall out. Not from the coolant in. It was also easy to see the coolant tabs deposits trying to fill the voids.

And yes, the coolant had been changed at 75K/4yrs w/tabs, by me.

Bill K – The timeserts poll thread seemed to tell me that most of the people who had head gasket leakage problems had the problem at about six or seven years and had never changed the coolant. Of course there will be exceptions to any such generalizations, no matter how much evidence there is for a conclusion because no generalization is absolute.

Please understand if I disagree with one point – the "no way." Corrosion of head gaskets by coolant can be a problem in any engine, except Duesenbergs and a very few other engines that have no head gasket. In the Northstar and other engines with aluminum blocks, the coolant can get in the head bolt wells and cause corrosion in the threads, and even the slightest corrosion there will cause the threads to weaken or fail when the head bolts are removed. Significant corrosion will cause failure of the threads with the head bolt in-place, and a head bolt pulling out. This happened with my car and seems to be the rule; it seems that it usually happens with an outside corner head bolt on the rear bank. Mine was on the driver's side but about half are on the passenger's side.

Your case is very interesting because it is the first hard evidence that I have seen that a problem can be caused without corrosion caused by the coolant. Do you have any pictures? Whether or not it occurred to you at the time to get pictures, I think it would be helpful to know the year that you changed the coolant, and the year and mileage that the head leakage occurred on your 1999 STS, and which cylinder(s) that showed the problem on teardown.

[JasonA]

The head bolts on the 2000+ vehicles are a little longer with a "coarser" thread pitch. So what? Engine improvements are a "constant change". Any particular improvement doesn't necessarily indicate a design flaw. You'll notice, via the Timeserting Poll linked above, that most people do NOT have problems with the head gaskets on their Northstar vehicles. Head bolt threads can be an issue with any engine. Go to Timesert.com and look at all the engine applications they make inserts for. Ford, GM, Honda, etc. It's not a "Northstar" thing. Remember that there are millions of Northstars running around out there with no issue. In fact, Cadillac seems to be one of the strongest GM brands right now, and its reputation and resurgence both were BUILT or VALIDATED by the new Northstar engine in the early 1990s. If these engines were truly lemons, they wouldn't have continued almost 15 years without a MAJOR redesign, or without being scrapped altogether. And now GM is installing the Northstar in OTHER GM brands, like Buick and Pontiac. It's a wonderful engine with a wonderful reputation, despite issues that some individuals have had.

[BodybyFisher]

There are glass are HALF FULL types and glass are HALF EMPTY types, the types that see development improvements as corrections of design flaws.

I will say this for that last time.. When I was a kid, cars lasted to about 100,000 miles and then they were JUNK, just tow them to the JUNK YARD. These engines will last a long time, IF I need to do a head gasket job at say 100,000 miles, I will fix it, and keep driving the SOB.... My friend has a 2000+ vintage Honda Odyessy?, and he just went for $2000+ for a friggen timing belt at 85,000 miles.... design defect? If I was a glass is HALF EMPTY type I would say, YOU BET YA...... because they cheaped OUT and could have used a steel timing chain.... A glass is HALF FULL type would say that fn engine lasted 85,000 miles with NOTHING but oil changes, if you would like to add X dollars to the purchase price we could put a steel timing chain on it... Someone is always going to be miserable...

To hear this:

No way can coolant cause the head bolts to pull and allow the gasses into the coolant.

While opinions are welcome, this statement completely stomps on and ignores the GURU'S statements that this is EXACTLY what happens (coolant intrusion into the bolt threads causes corrosion progressively weakening the threads, THEN the bolts pull)...... to me, to continue to refute this statement is thick headed. Any long term member should carry the Guru's explanation on this and understand this issue, not to mention that we continually repeat how important it is to maintain the cooling system.

When this headgasket issue began to happen, GM SHIPPED the affected NORTHSTARS BACK to the FACTORY for teardown and analysis... You can BELIEVE that they know EXACTLY why this is happening and you can believe that the GURU knew EXACTLY what was happening.... and he relayed that to us and highlighted the importance of maintaining the coolant...

[RichieR]

I'm new to this forum, so I'm not 100% up to date on why there are so many head gasket failures with the Northstar Engine. Is there a flaw in the design of the engine, head gaskets, etc? Is there a GM bulletin on it? Do the head gaskets just blow over time for no reason (other than design flaw), or is it a result of improper maintenance, etc.?

Any detail will be appreciated.

Ritchie -- too many people aren't aware that the DexCool 5-year protection limit means that if you never change your coolant, it will eventually become corrosive and get into the head gasket and head bolt wells and threads. If your coolant hasn't been changed in 4 years, you should change it ASAP. Unless you flush it when you change it (and many don't want to introduce tap water into their system), the change will be less than complete and you should take this into account in figuring how long before you change it again. I have set a time of 3 years for DexCool for my cars and I recommned yearly for green anti-freeze.

I've had old coolant go corrosove both on my 1997 ETC and my wife's 1999 Grand Am GT. On my wife's low-mileage car, I changed the intake manifold gasket and water pump and solved that problem. On my high-mileage Northstar I decided that a new engine was the most economical long-term approach.

Thanks for the clarification. Our '95 Eldo and '97 Deville were purchased new and we maintain our cars meticulously. We drain the coolant on both cars at or before the recommended intervals and we have had no problems at all. Also, I have to be honest with you - I have never seen the coolant temp in either of our cars go over 218F and it would only go that high if it were extremely hot outside with the A/C on. Most of the time, the coolant temp is between 198-203 F.

This proves a point though. If these cars are maintained properly, they will last a long time with relatively no problems. I have to believe that the majority of these problems are based on negligence. I know alot of people that think you just turn the key and drive, do no maintenance, and the car will take care of itself. That's obviously not the case. Not even with these great cars.

[Cadillac Jim]

BillK and all -- I'm concerned about a Northstar head gasket failing when the coolant was changed at 5 years. Since a 1999 could have been made as early as August 1998, the five year gong could have come as early as August 2003. But, BillK changed the coolant in July 2003. Perhaps, just perhaps, it was a little too close, some corrosion had begun in a head bolt well, and two years later it pulled out. This kind of thing is why I personally am recommending changing DexCool at 3 years and green coolant at one to two years. That's a bit conservative. But then, when it comes to maintaining my baby, I'm conservative. I got burned by thinking 100,000 miles when I should have been thinking 5 years, and never again. I don't think that dealers in general are conscious or aware of the importance of the five year limit on coolant corrosion protection because I've never hear of a dealer warning an owner to change the coolant at 5 years or sooner.

You will notice on the Polls section on timeserts that head gasket failures almost never happen in cars less than five years old. If it was a design fault, the failures would be just as probable in the first year as the sixth year. Most head gasket failures are in the sixth and seventh years.

Jasper uses a graphite head gasket that has seals around the water jacket passages as well as around the cylinder bores. Does anyone know if there have been similar changes in the gasket that GM uses in the Northstars?

[Bruce Nunnally]

Automotive engines do have head gasket failures. Let's look at at a couple of background articles on why this happens in automotive engines:

http://www.babcox.com/editorial/us/us80222.htm

http://www.aa1car.com/library/us697.htm

Most common industry causes for head gasket failures: preignition, detonation, and overheating.

Cooling system corrosion can cause coolant loss and even depressurization due to clogged pressure caps. The engine overheating due to inefficient cooling system can then cause detonation and head gasket failure. Head gasket failure then causes the engine to overheat, regardless of cooling system maintenance.

So I would guess that examination of a failed head gasket alone can not eliminate the cooling system as a culprit.

Clogged EGR passages can also lead to detonation.

Frequent short trips can lead to carbon build up, another cause of detonation. The northstar needs to be revved freely to keep it clean and blow the carbon out.

Finally, consider this article also:

http://www.asashop.org/autoinc/aug2003/techtotech.cfm

and this interesting quote:

To quote Jerry: "I can't believe how many people don't take care of the underlying root cause before replacing a head gasket. The gasket is a safety valve - if it is clamped up tight and it stays cool, it will last forever."

Also I found it interesting that the root cause of frequent head gasket failures on a neon engine was that the lower radiator hose clamp sealing was insufficient, allowing air to be drawn into the system.

Lots of things to consider on this topic, but my conclusion is that head gasket failure is not a cause, but is a symptom. When the head gasket fails, one has to look to the cause.

[Ranger]

With all the talk about Northstar head gaskets, I find it interesting (and reasurring) that the Northstar was not mentioned once in any of the above links.

[Bill K]

Its just when you have to pay $ for a N* HG that it becomes an issue. My son has a 94 Honda 1.5L that blew a HG(187K) and I was able to replace it at home in the garage for $150. or so including a water pump & timing belt. The Honda is a pleasure to work on although I dont want to drive it for over about 15 min.

Guess you gotta pay to play.

[Bruce Nunnally]

I remember Ian the mechanic saying he can have the powertrain out of a northstar and on his workbench to be serviced in 1 hour and 20 minutes. This leads me to believe that the dealer's huge charges for head gasket repair are fairly profitable for the dealer. However, they also bear the risk of ruining the block and replacing it, etc., which can turn a $500 repair into a new engine, so perhaps their experience is mixed and that leads them to the high charge rate.

[JasonA]

Its just when you have to pay $ for a N* HG that it becomes an issue. My son has a 94 Honda 1.5L that blew a HG(187K) and I was able to replace it at home in the garage for $150. or so including a water pump & timing belt. The Honda is a pleasure to work on although I dont want to drive it for over about 15 min.

Apples to oranges obviously. If your son had a '98 Acura NSX, you wouldn't be replacing those head gaskets at home in the garage for $150. I'm sure it'd be just as easy as your Honda to change a head gasket in a '94 Corsica, but where's the comparison?

[Cadillac Jim]

Its just when you have to pay $ for a N* HG that it becomes an issue. My son has a 94 Honda 1.5L that blew a HG(187K) and I was able to replace it at home in the garage for $150. or so including a water pump & timing belt. The Honda is a pleasure to work on although I dont want to drive it for over about 15 min.

Guess you gotta pay to play.

I had a piston seize on my Hodaka 90 cc motorbike once and I cleared the bore with my pocket knife and changed the piston while eating a hot dog around a campfire and had it running in a half hour. But I'd rather drive my ETC for daily commutes on the turnpike in traffic, vacations on the interstate, etc.

I remember Ian the mechanic saying he can have the powertrain out of a northstar and on his workbench to be serviced in 1 hour and 20 minutes. This leads me to believe that the dealer's huge charges for head gasket repair are fairly profitable for the dealer. However, they also bear the risk of ruining the block and replacing it, etc., which can turn a $500 repair into a new engine, so perhaps their experience is mixed and that leads them to the high charge rate.

My mechanic would not do a timesert job on my car. I asked "Why?" of course, and he told me that even the dealer had some come back. He didn't mention the Bigsert, but I feel sure that he didn't want to go there. He didn't mind me buying the eingine from Jasper and just paying him for the R&R labor, even though he has a customer number from Jasper and apparently does about an engine a week with them. This, the dealer cost of doing a timesert job, the leaking o-ring (not bad enough to replace or dripping on the garage floor yet but an omen for the next year or two), and a continuing struggle with oil burning -- and some posts here -- are what led to my decision to go with a Jasper remanufactured Northstar.

[truant]

Anybody have any more info on the headgaskets used by jasper???

My caddy should be done today. The new place I towed it to after the first one balked has been very helpful, and no questions asked.

[BodybyFisher]

Anybody have any more info on the headgaskets used by jasper???

My caddy should be done today. The new place I towed it to after the first one balked has been very helpful, and no questions asked.

Are they going to time-sert the block? Be 100% sure they do