Intake Gasket failure

[94CuttySL]

I don't have this problem....knock on wood*, but I want to prevent it, and I was wondering about how much it would be to have the gaskets replaced? I've never taken apart an engine and so I will probably just a shop do it, unless I found someone that could help me (besides my father).

I have 63,600 miles. The car was well kept. It was a one-owner vehicle, driven in winters (I have rust ). The older man that owned it, actually was my next-door neighbor, passed away, and the car sat for a little while. That's the history of it in a nutshell. I do notice some oil on the back of the engine and also under the TB (oil pump drive shaft seal o-ring?)...and for a while I was losing coolant but had no external leak that I could find. That was at least 10,000 miles ago that I noticed the coolant dropping a little here and there. It seems ok now, and the car has always driven extremely well since I got it at 48,300 miles last June. No issues. I drive it fairly hard sometimes too, but nothing has gone wrong.

Should I invest in new gaskets soon or should I have some time before I have a possible problem? Thanks for the help!

[3100 MPFI]

RE: Intake Gasket failure

the older 3100 does not have that leak problem like the newer ones. So far I have NEVER seen it on an engine with GREEN coolant. Only the ones with Dexcool.

The Job itself usually ends up being around $400-$600 depending on what all is done.

[3100 MPFI]

RE: Intake Gasket failure

Oh. If you want to do it yourself, it is not that bad of a job. The Alt, and power steering pump has to come out (or set to the side, for the power steering pump). The DIS has to come off, and the intake. Then all you do is remove the upper, and lower intake. You also have to undo some coolant lines.

When I did the intake swap on my 1996 Grand Prix, I could have done it all in a day if it was not for the fact that I had to order a part from the dealer.

[94CuttySL]

Re: RE: Intake Gasket failure

the older 3100 does not have that leak problem like the newer ones. So far I have NEVER seen it on an engine with GREEN coolant. Only the ones with Dexcool.

The Job itself usually ends up being around $400-$600 depending on what all is done.

Really!? I didn't know that. Thanks for letting me know. I was told by some others to keep an eye on my gaskets because they could go, which had me worried sick for a long time because I was losing coolant for quite a while. If this 3100 is not prone to that problem as much then that's great.

Can you explain the oil-like crap under my TB? I was told that there's an o-ring for the 'oil pump shaft seal' or something to that effect, under there and it could be bad.

I guess if I have the money some time I will change the gaskets just as a preventitive measure. I want this car to be running past 150,000 miles.

[geoffinbc]

Oil on the back of the intake spilling onto the tranny is most likely the oil pump shaft seal. It does leak and I had to change it on my girlfriends 1995. When you do the job you can cheat. If you are able to loosen the clamp and pull it up you can spray the area with brake cleaner, let it dry and then pump it fulll of RTV. Give it a couple turns to spread out the RTV and then clamp it down again.

I opted to remove everything and do the intake gasket aswell when I did the job.

If you do it the real way get a new o-ring and also add the gasket from a Small block chevy distributor. This will double the sealing.

[Doubt_Incarnate]

interestingly enough, you say the dexcool cars leak more often. i've even heard that the dexcool attacks plastics. that makes sence since the gaskets for the 3x00's are plastic with rubber "o-rings". what would it take to convert to green? do you need new sensors? my ls1 is dexcooled, and the intake manifold, is plastic...

[94CuttySL]

Oil on the back of the intake spilling onto the tranny is most likely the oil pump shaft seal. It does leak and I had to change it on my girlfriends 1995. When you do the job you can cheat. If you are able to loosen the clamp and pull it up you can spray the area with brake cleaner, let it dry and then pump it fulll of RTV. Give it a couple turns to spread out the RTV and then clamp it down again.

I opted to remove everything and do the intake gasket aswell when I did the job.

If you do it the real way get a new o-ring and also add the gasket from a Small block chevy distributor. This will double the sealing.

Excuse the naive question, but where exactly is this seal/o-ring? All I know is that it is under the TB... Thanks

[geoffinbc]

Its not the Dexcool. It happened when they switched to roller rockers and with it the gaskets changed. I guess they changed to shitty gasket material in the process.

[Cliff8928]

That's funny, they switched to roller rockers somewhere mid 1995 or so, however the faulty gaskets are only on the 3100 "J" and 3400 "E" (large-runner intake) engines, not the 3100 "M" (small runner intake) engine.


Cliff Scott
89 BerettaGT <-1999 3400 still on original intake gasket
04 AleroGX

[94CuttySL]

That's funny, they switched to roller rockers somewhere mid 1995 or so, however the faulty gaskets are only on the 3100 "J" and 3400 "E" (large-runner intake) engines, not the 3100 "M" (small runner intake) engine.


Cliff Scott
89 BerettaGT <-1999 3400 still on original intake gasket
04 AleroGX

Ok, so I have the 3100 M code engine, so I shouldn't have this problem? The gaskets are different?

[geoffinbc]

Yes

But intakes still do leak on ocasion otherwise. But it is just not as certian a problem as the above motors.

[94CuttySL]

Thanks for everyone's input. I know all the 60* V6'S have gasket issues for the most part. I know people who have had problems on the vin M engines as well, and know people who know others who've had problems. I'm going to get them changed just to be safe. I'll be doing the oil shaft seal as asap well.

[Cliff8928]

Yeah, i didn't say that they never leak, just that the "M" engine isn't the one GM admitted to being faulty.


Cliff Scott
89 BerettaGT
04 AleroGX

[94CuttySL]

Yeah, i didn't say that they never leak, just that the "M" engine isn't the one GM admitted to being faulty.


Cliff Scott
89 BerettaGT
04 AleroGX

True.

I was told Fel-Pro are pretty good gaskets. I'll look into those. I'd like to do the work myself so I can learn some. I'm still deciding.

[3100 MPFI]

the lower intake was leaking on my Grand Prix when I put the Vin J manifold on it. The 96 also uses DEXCOOL.

What it is, is when GM put them on, it CRUSHES the area that seals around the coolant passages. I have heard that Dexcool eats away at the RUBBER, not the plastic. Makes sense to me seeing that when I took the old gaskets out, there was almost NONE of the blue rubber/silicone left.

As far as I have seen, 1996 was the FIRST YEAR to get the roller rockers. In MID 1995, they started making it so the heads could have them, but so far, I have NEVER seen a 1995 with roller rockers from the factory. And I have also NEVER seen a 1996+ with the STAMPED STEEL ones.

This is the OIL PUMP DRIVE. You just take the 1 bolt off, and the metal retainter, pull it up and out. You MIGHT have to take the crossover off to do it. The Throtte body HAS to come off. I replaced the O-ring on the Grand Prix when I put the larger upper, and lower intkakes on.