PontiacBonnevilleClub.com

85,000 mile car, complete service record available.

The biggest worry is the head gaskets. Is it a question of when, or a question of if?

I love the car, but blowing the head gaskets out worries me. A lot. Please tell me many of these cars go 200,000 miles without blowing theirs!

Is there anything I can do maintenance-wise to help ensure they don't blow?

The head gaskets appear to go both with mileage and with age, it is a question of when, not if. There are no proactive actions to prevent the head gasket issue. If you buy a GXP, have 4k in the bank and hope that is enough to perform the repair, and hope you have a qualified person in your area to perform the work.

There is a reason 2005 GXPs are now often selling for less than 2005 SLEs. The GXP is a very, very expensive and high risk to maintain automobile.

MikeKerr wrote:The head gaskets appear to go both with mileage and with age, it is a question of when, not if. There are no proactive actions to prevent the head gasket issue. If you buy a GXP, have 4k in the bank and hope that is enough to perform the repair, and hope you have a qualified person in your area to perform the work.

There is a reason 2005 GXPs are now often selling for less than 2005 SLEs. The GXP is a very, very expensive and high risk to maintain automobile.

Respectfully, have you ever owned one of these? I'm not sure that you're providing completely accurate information. Head gaskets are not nearly the problem in the GXP as they were with prior versions of the Northstar. Some do still have issues, but I can rattle off a whole list of vehicles that have had head gasket problems. Many people seem to jump on this bandwagon with little first hand, direct experience. When a few people make a big deal about something, all of a sudden everyone around joins in. This is simply human nature. I have spoken with many GM technicians who have states these are (now) a pretty solid engine.

I had over 235,000 on mine & it's still running in Iowa now with about 240,000 on it.

MikeKerr wrote:The head gaskets appear to go both with mileage and with age, it is a question of when, not if. There are no proactive actions to prevent the head gasket issue. If you buy a GXP, have 4k in the bank and hope that is enough to perform the repair, and hope you have a qualified person in your area to perform the work.

There is a reason 2005 GXPs are now often selling for less than 2005 SLEs. The GXP is a very, very expensive and high risk to maintain automobile.

Seriously, what ddalder said. Mine has 170xxx miles and still no HG issue.

A couple months ago I bought an '05 Bonneville GXP with only 32k miles. I've checked it over and changed the coolant. The head gaskets are still fine after 10 years. So, I agree with the other posters, that head gaskets on the 04-05 GXPs seem to be no worse than any other similar cars.

I personally bought one cheap with blown head gaskets and have seen a handful of others with blown gaskets as well. Is it a possibility? Absolutely. It is not for certain though. I wouldn't hesitate at all to snag another one, even if it had a head gasket issue now or in the future it is well worth fixing and enjoying after it's done. With the SSEi you get a weak trans that would cost ~$2,500 to repair and with the GXP you get a solid trans but the possibility of head gasket issues that cost not much more to repair then the trans but you get nicer styling and best of all V8 rumble. Drive it, love it, don't worry about it, I have seen far more without head gasket issues then I have seen with.

ddalder wrote:

MikeKerr wrote:The head gaskets appear to go both with mileage and with age, it is a question of when, not if. There are no proactive actions to prevent the head gasket issue. If you buy a GXP, have 4k in the bank and hope that is enough to perform the repair, and hope you have a qualified person in your area to perform the work.

There is a reason 2005 GXPs are now often selling for less than 2005 SLEs. The GXP is a very, very expensive and high risk to maintain automobile.

Respectfully, have you ever owned one of these? I'm not sure that you're providing completely accurate information. Head gaskets are not nearly the problem in the GXP as they were with prior versions of the Northstar. Some do still have issues, but I can rattle off a whole list of vehicles that have had head gasket problems. Many people seem to jump on this bandwagon with little first hand, direct experience. When a few people make a big deal about something, all of a sudden everyone around joins in. This is simply human nature. I have spoken with many GM technicians who have states these are (now) a pretty solid engine.

You saved me a lot of writing.

Does anyone know what specific changes GM made to the Northstar in later vessions, to rectify the problem?

In general, the year 2000 introduced longer head studs to the NorthStar. In 2004, more coarse stud threads were introduced to improve the clamping ability of the head studs. These changes seem to have eliminated almost all of the earlier head gasket issues.

Just some things I seem to recall... 2000 was the major engine revision;

- New cylinder heads that allow static lash adjusters and roller followers
- Larger intake valves with less shrouding in the combustion bowl and smaller exhaust valves.
- All valves have longer stems.
- New magnesium camshaft covers.
- New crankshaft with a revised reluctor wheel and a new front cover to accomodate the larger diameter front seal.
- Cast connecting rods (originals were forged).
- Flat top pistons (no valve releif's like earlier versions had).
- New wrist pins on the pistons.
- New Harmonic balancer.
- New right bank exhaust cam sprocket to accomodate a new camshaft position sensor.
- New CKP sensor.
- New knock sensor.
- New EGR passages on the exhaust side.
- New CNP ignition system that puts all 4 coils on a "cartridge".
- New coolant crossover.
- New Intake, fuel rails and injetors.
- new spark plugs
- Camshafts were not drilled for oiling. Journals instead were oiled from a gallery that ran along the head.
- Longer head bolts. M11x2 vs. M11x1.5.
- 10:1 compression (lower than previous models) to help address the stud issues as well as being able to run on 87 octane.

Late 2000 and 2001's
- New exhaust manifolds incorporate EGR

2003;
- 13mm timing chain tensioner bolts. Prior versions had 10mm.

2004/5;
- New knock sensors.
- Oil filter mount now has 3 bolts and a one piece gaske instead of 2 bolts and 2 "O" rings.
- New Magnesium camshaft covers that do away with the spring ground for the "cartridge" Now each coil is grounded through the cover, to the head.
- New "domed" pistons. I'm using the term "domed" loosely. The centers of the piston were raised vs the edges (circumference of the piston), to help with CSK.

My low mileage 05 GXP had HG failure not long after I bought it.(3 1/2 yrs. ago) I know some don't like aftermarket service warranties, but, mine only cost $2000 at time of car purchase, not long after, it covered approx. 99% of a $4000.00 plus repair bill at the Mr. Goodwrench - Cadillac dealer. Money well spent IMO. Some also defend the Dexcool that has cost GM lots of money in various lawsuits due to it's corrosive properties under certain conditions and a direct relation to many of the HG woes. I would recommend an immediate flush and refill of the cooling system if you get the car. The brand and "color" of antifreeze used are up to you. I switched to the "mixes with any color" Prestone stuff as soon as the repair job's warranty ran out. Unfortunately, the dealer wouldn't consider using the head "studs" for the repair and used the "timeserts" which are nowhere near as reliable down the road. If you ever do have to do HG's, I'd strongly suggest that you go with the stud kit ! There is nothing like the sound from the N'star, just be prepared to pay to hear it. Good luck & have fun !

I'm the guy that disagrees with 3rd party warranties and I'm the guy that defends Dexcool.

But what do I know.

Never too late to change. (your coolant or your mind) Not sure why I'd wanna' bit@h about saving $2000.00 by getting a warranty, either. I know they can be a pain for the techs/shops but, I am neither of those.

No need to change when I've never had a problem.

That's cool. Murphy dogs me everywhere I go and kicks my butt on a regular basis.

I also seem to recall there was another change to the head bolts in 2004. All GXP LD8's got the new ones but only some of the 2004 DeVille LD8's did. Every DeVille had them for 2005.

I don't think the size changed though. May have just been a revision.

Something tells me it was thread pitch only. The parts department lists two different bolts for the Cadillac LD8 (depending on engine revision ID) but only the new one for the Bonneville. There was discussion about this on the Cadillac forum which if I recall, Chris at Rippy Cadillac had confirmed through his channels. Just haven't had time to dig it up again...

Thanks for rebutting my post- more information to the OP the better. In my case I owned a 2005 GXP that blew its head gasket at 92,000 miles. My SSEi at 233,000 miles still has original engine and trans and seems to want to run forever, except for the brake and fuel lines rusting and subframe rusting. I could of reduced the rust exposure some years ago had I known the SSEi drivetrain was going to outlast the subframe.

On my GXP, I was unable to do the head gasket repair as I did not have a lift. I had a very hard time finding a mechanic that would do the head gasket repair. The N* was packed in so tight, seemed many repairs that were simple on the SSEi were major challenges on the GXP. I love the GXP, in my case the GXP is to expensive a risk to own.

Others have shown my experience and thoughts may be far from the standard experience and thoughts on the GXP.