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Another GM 3.1 Liter Engine Means Another Intake Manifold Gasket Coolant Leak

I now have a 2000 Buick Century with the 3.1 Liter engine. It only has 60 thousand some miles on it, but by now I am adding 1/2 pint coolant about once a week. There seems to be a chronic intake manifold gasket problem with this engine. I am not looking forward to the time and difficulty I am facing in changing out this gasket like I had to do twice on the Regal I had several years ago, being without a car for a while also. I know GM has put their recommended cooling system sealant in the engine, but it still leaks. On the Regal the leak became very bad in a short time. So I expect this to happen with my Century. But might there be a sealant on the market that could actually seal up my intake manifoild gasket leak?

If someone came out with a product that would stop GM intake manifold gasket leaks, I’d be using it.

That’s why the gaskets must be replaced.


+1 to @Tester, this is common with this engine. You can try the magic stuff you pour in the radiator, most have sodium silicate as the active ingredient. Most folks report a low rate of success and when it does work it is temporary. Your local mechanic has seen a lot of these and can turn your car around pretty quickly.

It’s a near certainty that nearly every 3.1 from that era needed to have those gaskets changed. They were made of a fiber material with polymer rings. The fiber material would turn to mush when used with DexCool. The good news is that the updated gaskets are made of aluminized steel with polymer rings. These provide a more permanent fix. It’s not a major repair.

Sounds like this is a common problem w/these engines. Just curious, has anyone had success stopping or at least reducing these leaks by re-torqueing the bolts that hold the manifold to the head? Or does the engine have to come out to access those bolts?



I am not looking forward to the time and difficulty I am facing in changing out this gasket like I had to do twice on the Regal I had several years ago, being without a car for a while also.

After buying a good used car for a small fraction of the price of a new car I enjoy spending a few hours performing a repair like this. If this is the greatest problem with your 16 year old car you aren’t doing too bad.

I am suprised you can seal them at all,that design never did impress me ,give me a 3800 or a Vortec anyday .

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It's not a major repair.

It is if you let it go leaking for too long…then it’s a major repair.

Thanks for advice. I obviously would be wasting my time with any kind of sealant.


those other engines you mentioned also have their problems . . . including intake gaskets

Another bit of curiosity, what is the function of routing the coolant to the intake manifold in the first place? The intake manifold shouldn’t really need much cooling should it? Is it b/c there’s sensors or actuators in the intake manifold that need to know the coolant temperature?

Never heard of much trouble with a 4.3 ,if you kept that horrible orange antifreeze out of it .GM makes great running engines,but I dont like how some of them are put together.


I am going to vehemently disagree with you . . . using dexcool is not the reason for leaking gaskets

GM still uses it, but you don’t hear about leaking intake gaskets on newer design engines. Not much, anyways

The problem is the gaskets themselves, not the Dexcool

If dexcool was so evil, GM would have stopped using it.

We’ve been through this countless times, and I’m pretty sure nobody’s going to change anybody’s mind

You know you’re right

And you know I’m wrong

I know I’m right

And I know you’re wrong


I could agree with you and we would both be wrong,the orange stuff has a very limited lifetime and the scoop around here is replace it in anything that contains it and replace with the good stuff(green and you are set for many years,an interesting sidenote is ,I dont think GM has produced the years old engines like the 3.1 for awhile ,so newer engines less trouble .( you could be right ,I never liked the design on these particular engines anyway and frequent coolant changes would probably take care of the problems,but make mine green ,I have never had gasket problems on my V6 engines ,but then again I avoid V6 engines produced by the Big Two.

I assume that comment was meant for me . . . ?

I’m at something of a loss, as to the purpose of your comment . . . ?

6 months ago . . . ! . . . I made it abundantly clear that I’m not changing my mind about dex-cool, and I also said I don’t expect to “win anybody over” to my side, if you want to call it that

You are correct . . . the older design engines have been out of production for some time now. The 3.1 hasn’t been built for several years, AFAIK. The 5.7 liter V8, 7.4 liter V8, and 4.3 liter V6 have also not been produced for several years

When you say that you avoid the Big Two’s V6 engines, I assume you mean Ford and GM

What about mopar V6 engines . . . I know they also have their problems, but I’m not sure if gaskets are one of them?

I own one from the "Big Half " it doesnt quite have 100K on it ,it makes unique noises and I fully expect it to detonate before long and you are right these Powertech sixes have unique problems all their own ,Mopar should be ashamed for producing something like that ,when they already had 2 engines that were proven with more output then the 3.7.
My apologies if I sounded harsh,I just get aggrevated when the manus foist poorly engineered stuff on the gullible public ,my experience with the big half has taught me to stay away from their wares .

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Well the thermostat is in the intake for one thing.

Mr. Breeze , if you look at the right side of your screen you will see that date of the posts. The last post on this thread was OCT 2016 .

The other left :wink:

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