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Select one if you have had a problem with the headgasket the Northstar V8:

Northstar Headgasket/Cracked Block/Bolt Failure? Please let us know

294K views 546 replies 243 participants last post by  ihc70 
#1 ·
Here is the Definitive Northstar Headgasket Thread. Please choose your year of Cadillac and state if you have had a headgasket problem with your Seville or Eldorado and what mileage it occured at. If you have never had a problem please do not participate in the poll!
 
#60 ·
A friend of mine's 99 Seville just popped one... Crap...

So, easier to fix the engine with all the work or just drop in a LS4 out of Impala SS/Grand Prix GXP?

Has the swap been looked at? The PCM doesn't have to know there is a LS4 there instead of a N*....
 
#62 ·
Had a 94 Concours go bad. Rear gasket. Then head bolts stripped out. Junked the car after sitting 4 years. Approx 150,000 miles. Learned from a car dealer friend to always sniff exhaust pipes and check by hand feel(sticky) for antifreeze even if oil looks good. I have had 3 more N*'s and still have a 4.5 Allante, now that I know what to look for. I'm sure these quality problems are a big part of the poor resale value of Cadillac's overall.
 
#63 ·
How reliable the fixes? New gaskets/timeserts hold up?
 
#64 · (Edited)
I'm going through it now. Dealer maintained religiously. Never abused. 97,000 miles. :banghead:
I love the car (Concours Deville), am now hating the motor. If I fix it, I will sell it and buy a 93 or 94 Fleetwood. I bought this after swearing off of Fords because my Expedition had a problem with spitting spark plugs out of the aluminum heads. I may just go back to an older classic with a nice 327. These manufacturers seem to be taking advantage of us with inferior cars and higher prices.
 
#65 ·
I can be completely honest, I original was looking for a 94-96 Concours Deville, but once I started hearing about the head gasket issues on the N* I started looking at the Fleetwoods and ended up buying the first one I looked at. Ended up being a factory V4P car (7000# tow package). I need dead nuts reliability, I have already put 100K on my FW since Feb 05. I can't risk down time nor expensive to fix. The LT1/4L60E/Conventional RWD chassis fits the bill.

Ford Expeditions are just awful on mpg from all the owners I have talked, actually, anyone with a 5.4L says they get 12mpg and that is it. My 350 Suburban NEVER got below 12, and typically got 13.5-14, and 15-17.5 on the highway. Forget Ford and good mpg on the mod motors, in a truck they just don't have it....

I want a car that I can drive daily, hot rod and enjoy the heck out of it, but still rely on it, and in the end, be able to fix it if I had to (remove engine/trans myself in my garage instead of relying on a shop to do it for me)
 
#66 ·
My father-in-law swears by the Cadillac with the Northstar engine. He has had 3 or 4 in the last 10 years, all kept under 60k miles before trading. I had become a Mercedes person. So, my wife was needing another car and we decided to buy a 2000 Deville with 74k on it. I have put 8k on it and now have a job of replacing the headgasket if the dealer will do it. I have had one external mechanic tell me that the recommendation from Cadillac is replace the motor in stead of repair due to the aluminum motor. This will probably be my only gripe session on this subject, but thought I would share my thoughts. I love the looks and the ride of the Deville. I have talked to many Cadillac mechanics and they say that it is normal that the Northstar engine use a little oil. Mine does, but that is not that much of an issue to me. I do not accept that it is normal for a car new to 100k miles to use oil. I have a 1990 Mercedes with the v8 that uses zero oil and that car has 179k on it. It also does not have a head gasket problem and require the replacement of the motor. My opinion, the Cadillac produces very stylish and comfortable cars, but the Northstar engine is nothing but junk. I hate to get rid of the car because I like the car as far as looks, but just as soon as I can get it repaired and/or trade it, it will be my first and last Cadillac. GM just proved to me what I have thought for years, that they produce junk at premium prices. I understand that if a car is abused such as running it with low oil often and never changing any of the fluids, there can be problems, but a headgasket to blow after 82k is not likely due to abuse. It is possible, but not likely. It is more likely that it is just a faulty piece of machinery. Right now, there are 4 other Devilles that are 2000-2001 that are at the dealership with the exact same problem as mine. That is just unacceptable. And the Dexcool coolant that is used from the factory is junk that probably cause many of the problems. It gums the radiators, thermostats, and the probably the waterpumps up. It sets up like wax. Also, if you are getting the message on your dash that you need to check the coolant level, then your sensor has been gummed up by this Dexcool and will probably need to be replaced. Sorry for the gripe session, but I am very disappointed with the Cadillac product. I will go back to the Mercedes for my wife. I own 2 currently and as soon as I can get the Cadillac fixed, will be trading it in for a 3rd Mercedes. I have owned 3 now with one having 220k on it and never this kind of problem.
 
#68 ·
I have a 1990 Mercedes with the v8 that uses zero oil and that car has 179k on it. It also does not have a head gasket problem and require the replacement of the motor. My opinion, the Cadillac produces very stylish and comfortable cars, but the Northstar engine is nothing but junk. .
Well I am a Mercedes Benz technician and I was a dealer tech from 1982 to 1999.
I now work at an independent MB shop. Head gasket problems affect MB engines just as badly as Cadillac.
Back in the early 80's the M116 or 380SL 380 SEL and 380 SEC all had head
bolt issues. "When" the headgaskets had to be replaced the headbolt threads
pulled and thread inserts had to be installed in the aluminum engine block.
81,82 and 83 engines were affected. In 84 the changed to nickel/chrome bolts.

And don't get me started on the timing chain B/S. In 1982 when benz went to the 380 engine (M116) from the
cast iron block 450 (M117) they changed from a double row chain to a single row. Well they were coming in with
30K miles with a broken chain and bent valves. Warranty covered the repair but imagine the cars that made it
out of warranty. Again, in 1984 they switched back to a double row chain.

As recently as 1999 the M104 built from 1991 on has cronic headgasket leakage problems.

There's not emough room to list all the problems I've seen with
Mercrdes Benz in my 25 years of experience working on them in one post.
 
#67 ·
I still stand by as the #1 most reliable Cadillac is the LT1, but honestly, could be tied with the L05, the 307 Olds, and then the 4.9L, with the injectors being the real issue with 4.9L's and main bearing thump. The LT1's had some early problems with the Opti's, and the L05's nothing that I can really think of.

I honestly don't know much on MBenz, but I really did fall in love with the 2000 prototype S500 I drove (freaking rocket for a big car!), the one we had was around S/N 300, made in Oct 98 or so. Not sure on reliability, but I sure would love one....
 
#70 ·
Quality of Benz down? Did Chrysler do that much to them?
 
#71 · (Edited)
Speaking of MB, I was not saying that they never had any problems. I was only stating that you would very rarely find a MB with only 82k on it with this problem. MB's prime cars, in my opinion were the w126 series. Although I am sure there were some problems, I have had MB mechanics here tell me that was when MB made a name for themselves as far as longivity. I have had 3 MB, one had 220k and running perfect with no oil consumption and never had a blown headgasket before I sold it, one that I still currently own with 179k on it and has never had a blown headgasket and another one I own currently with 91k and so far no problems. I talk to more and more MB owners and rarely do I find where there has been a blown headgasket, even with 150k. Since my ownership of my 2000 Deville and the problem, I am running into more and more Cadillac owners with the Northstar engine that either have had this problem or are having it currently. Again, 4 in the dealer with the same problem at the same time, is unacceptable. If you have a Northstar with 60k on it, my advice for what it would be worth would be to get rid of it an trade it. I have already warned my father-in-law because his has about 50k on it and he has admitted that he is starting to have some minor computer problems. All manuafactures have their problems, but I just feel Cadillac has let us all down in not addressing the issue and tring to get it fixed where there would only be rare cases show up. New Years Eve in NY, there was a major GM adverstisement on one of the screens on the street there. I told my wife, they should have taken some of the millions spent on that and put it into the research to fix some of the problems such as blown headgaskets at 82k. My main point I was trying to get across is that, sure all have their problems, but the chances of getting a MB with 82k with a blown headgasket are much less than with the Cadillac. My chances are already less in that I have had 3 MB, all with more miles than my Deville, and the Deville is the one with the problem. And, with Cadillac making the recommendation to "replace" the motor versus fixing it, tells me that they like selling new motors to people. And, they won't resolve the problem as long as they can sell a new motor every 80k miles at a cost of $4000-$7000. If Cadillac was smart, they would do the research and fix the problems to reduce the chances of having this problem and in turn, people would be more willing to buy Cadillacs over and over. That is one reason I have grown close to MB. Yes, I have had problems in the past with the ones I owned, but when you have something go wrong with 150k or 200k on the clock, you tend to realize that they won't last forever and you don't mind spending the money to fix. But when you get one as young as my Deville, it makes you think that it is just not a well built car.
 
#72 ·
My thoughts are: GM found this problem early on it the life of the N*. Back in the early 90's. It should never have escaped 1994 at the latest. They HAVE the tools to figure this out, and to eliminate it. If it takes some WORK, then do so. My LT1 is over 240K now (just barely) and I stomp on it often, no blown gaskets. I can't imagine a small block Chevy "dealing" with issues like that. It is further more embarassing that Cadillac does.

GM's quality is supposed to be good based on QS9000/TS16949. But they still won't take it seriously. They are learning that painful lesson now, as Toyota IS taking it seriously and starting to outsell GM. It is truly sad that GM won't get serious. I hate to say it, a lot of it is the quantity vs quality mentality, and I am sure the unions aren't helping anything. GM needs to stop beating the snot out of the suppliers for the problems they have and take the roll they need to be in and use it to do what they need to do. GM is their own worst enemy.

Motorola wrote the book on quality with the Six Sigma and Digital Six Sigma programs. GM needs to get into school and LEARN it. They WILL eliminate the quality defects quickly and effectively. It will teach them how. If you apply the principles of Six Sigma, you CAN'T have bad quality. But you have to apply them. You have to WANT to have good quality.

GM has the 5 Phase Action Plan should also show the issues. Ford uses the 8D for problem solving. Both are similar, they both accomplish the same thing. But they have to be used!! Take that and apply Six Sigma and you WILL eliminate the quality defects that plauge the company!
 
#97 ·
Great posts. I agree 100%. I've always had a concern about pushing the Six Sigma as being able to solve all quality problems. It just stresses holding all tolerances to the middle of their range. This is a good thing for sure, but if the base design is flawed, all the tolerance holding is worthless. They need to put just as much emphasis on getting the base design correct as they do on holding tolerances. I think a good design should actually allow for wide manufacturing variations while still maintaining design integrity.

The 5 Phase Action Plan should solve this (IF they really want to do it,) but they have to accurately determine the Root Cause. In this case it seems to be a moving target.

GM has always been bad about fixing something once it's in production. I had a 2002 GMC Sierra. An absolutely wonderful vehicle, except that at 30k miles the cable tailgate straps broke and dented the tailgate when it dropped and hit the bumper. I knew about this problem for at least 10 years prior on GM trucks from all my buddies having the same thing happen. It always confused me why the entire truck was an engineering marvel, but they dropped the ball on something as simple as the tailgate straps.
 
#73 ·
I dumped my 94 when the headgaskets started to go. The car had 187k on it though so I think they where due to go.
I wish the car was in better shape cosmetically because I would have paid the money to fix it.
 
#74 ·
Would it hurt the car to change back to the green antifreeze ?
I plan to drain my dexcool and refill it every year or two hopefully that will keep it fresh.
 
#79 ·
1996 Seville SLS at 132,000 miles. Two previous cooling problems precipitated the final failure; Impeller and radiator went out.. The OAT orange coolant starts eating the gaskets from within, once air ever gets in the system.

Same thing happened to my 2000 Chevy Venture. Did a top end to that engine, and started using green coolant and all cooling problems fixed.
 
#80 ·
So will timeserted block survive long duration?
 
#81 ·
As for my 1996 SLS, I have not yet decided if I'm going to time-sert the block, get a used engine, look at the LS4 5.3 transverse engine swap, or just take this beautiful car to the junk heap and call it quits. No one seems to want to buy a good looking car with any problems. Still runs like a sewing machine, but you can smell coolant from the exhaust and overheating is a crap shoot. 5 miles or a 100 miles, ... it is unpredictable except that it will overheat.

I should probably start a new post for help on this issue.
 
#91 ·
As for my 1996 SLS, I have not yet decided if I'm going to time-sert the block, get a used engine, look at the LS4 5.3 transverse engine swap, or just take this beautiful car to the junk heap and call it quits. No one seems to want to buy a good looking car with any problems. Still runs like a sewing machine, but you can smell coolant from the exhaust and overheating is a crap shoot. 5 miles or a 100 miles, ... it is unpredictable except that it will overheat.

I should probably start a new post for help on this issue.
I would say fix it and buy a better gasket and the motor will last dam near forever. Think about it more like this it's probably the first major repair right ?
So why not fix it and go another couple hundred thousand miles ?
 
#82 ·
Is an LS4 swap viable? A friend of mine wants to know, his N* is starting to use coolant (steamy exhaust, makes a nice cloud at times). I am pretty sure it hasn't come close to overheating, he bought a new Jeep so the Cad is now parked.

He has a 99-00 SLS. He wants to get it back up and running, I mentioned a LS4 swap is possible, but we need to know details.

Any help/advice either way is very welcome.
 
#84 ·
So basically the failure mode is coolant leaks into the threads of the head bolts, corrodes the block, and the head bolts give way and you are done. So somehow you need to absolutely prevent coolant from ever getting to the threads.

What did BMW do it to fix?

GM should revisit the main bolt concept on the 427 Hemi Pontiac. They had spayed main bolts and the lower head bolts were long and went into the main caps. The upper head bolts went into the block deep, well past where the bores were so no bore distortion could happen when the heads were tightened down. This is a long Pontiac design already on the top bolts, but the bottom never got into production.
 
#85 ·
So basically the failure mode is coolant leaks into the threads of the head bolts, corrodes the block, and the head bolts give way and you are done. So somehow you need to absolutely prevent coolant from ever getting to the threads.

What did BMW do it to fix?
Well, then the failure mode is not similar to BMW's. With the BMW, the head bolts were purposefully stressed to the point of stretching and using the elastic properties of the metal to compensate for expansion of the all-aluminium block and heads. Sort of like holding the heads with really strong rubber bands. Probably works great in a Formula One engine intended to last 400 miles. Not so great for a passenger car engine. The bolts would stetch a bit too far and couldn't return to their previous length. When I pulled my head bolts, average torque remaining in the bolts as about 35 ft lbs, due to this overstretching.

Ask a mechanical engineer about the stress-strain curve, the yield point, and the modulus of rupture.

Sounds like the Northstar is more similar to the old Jaguar 6. As Jag expanded the displacement over the years they extended the head studs deeper into the block to the point the studs ran through the water jacket. If you didn't keep the coolant super clean the studs would corrode. The engines were so dammed overbuilt that you probably still wouldn't lose a gasket, but it was hard to remove the stud without leaving 1/2 the stud behind if you ever had to pull the head.

Does the Northstar expose the head bolt directly to coolant or does failure first require something else, like a cracked waterjacket or a partial loss of seal at the headgasket?
 
#86 ·
Sorry, I didn't phrase it well, I am guessing that is the problem, not sure if it is. A lot of people seem to blame the antifreeze so that is my guess.

I sure would like to know the actual engineering analysis for the failures. And is it repairable to make the engine truly reliable.

I am worried on my mom and dad's 97, they are @ 105K on GM installed antifreeze...... I found a trace of coolant on one sparkplug, so I am concerned they are on borrowed time.... The car doesn't drive much anymore, but still gets driven several times a week....
 
#87 ·
Actually, the "explanation" of antifreeze corroding the bolts makes perfect sense. The overall problem still sounds much like what I've seen with the Jag 6, through the problme is not limited to that engine and is a fundamental issue with any aluminum motor.

The basic issue is that because of the greater expansion of aluminum, an all-aluminum design puts much more stress on the head gasket--it gets squeezed tighter when the engine is warm and has to expand more to fill in the gaps when the engine is cold. After 1000's of cycles, the gasket will lose some of it elasticity and no longer seal completely. Small leaks from the water jacket result, and if the antifreeze is old, the headbolts (which are iron or other metal susceptible to corrosion) will corrode and eventually fail.

With the Jag, the solution was to change the headgasket at 100,000. You didn't wait for a failure; this was considered normal maintenance. The good part was that the engine was so overbuilt that you only changed the gasket--the timing chain, valve seals, etc., were good to 150k easily.

BMW (and others) have tried to avoid this problem by designing the head bolts so they stretch and take some of the load off the gasket, which can be made out of very hard and tough material. I still have one out of my V12, and it likely is vulnerable only to A-bombs and cockroaches :)

Us red blooded 'mericans are used to driving cast iron blocks and head forever without head gasket issues. Those times are gone.

I wonder if GM when the extra mile with the STS-V and used a better gasket material?
 
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