Detect which intake manifold is leaking

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[DevMcLin]

Hi,

the Lumina 1998 3.8L Series 2 from my girlfriend is loosing some coolant.

Its about 200-500ml in a month.

Now I want looking where the coolant leaking.
I read something about upper intake manifold but I read also something about the lower intake manifold gaskets.
The Lumina is smelling like burned plastic after the engine is warmed. So my opinion is that the upper intake manifold is leaking, but I found on Google its good idea to replace both the upper intake and the lower gaskets.

So what did u think?
Oh and there is no coolant in oil, or the oil is not looking milky.

[SofaKingWeToddDid]

do both, its so easy to take off the Lower intake when u already have the upper taken off, plus if it turned out to be the bottom and u skipped out on it, well ur taking it all apart again just to cover the base u skipped out on being lazy.

just do it, get the set and replace all the gaskets around and under the LIM too. (does the 3800 have any like the 3.4 under the LIM?) well i would do them both is all im trying to say.

[Prospeeder]

its the lower one that leaks the coolant. Be aware, with the plastic manifolds, they had an EGR right on it and it was said to warp or melt to plastic and cause coolant leaks

[SofaKingWeToddDid]

its the lower one that leaks the coolant. Be aware, with the plastic manifolds, they had an EGR right on it and it was said to warp or melt to plastic and cause coolant leaks

WTF?!?! an EGR bolted to plastic? whos rocket scientist idea was that? next thing ya know the mufflers and exhaust manifolds are going to be made out of plastic too.

[DevMcLin]

I ordered the Intake Manifold Set and the Fel-Pro Intake Manifold gasket kit ,with all gaskets.

I dont open the engine without new parts. I report then what the failure was.

[XTRevolution]

I ordered the Intake Manifold Set and the Fel-Pro Intake Manifold gasket kit ,with all gaskets.

I dont open the engine without new parts. I report then what the failure was.

How many miles on the engine?

I replaced the upper intake on my sister in law's 96 Regal before it had a chance to crack. That's a problem you're better off fixing before it gets worse.

The LIM gaskets were toast on her's. I hope you got the revised aluminum LIM Gaskets, because the plastic ones will just leak again in roughly the same mileage.

[DevMcLin]

It has 175.630 km is an canadian model.

I ordered Dorman 615180 and Fel-Pro MS98014T.

[SofaKingWeToddDid]

so ur sayin its better to get rid of the pastic manifold with the egr attached and get the aluminum one?

[XTRevolution]

so ur sayin its better to get rid of the pastic manifold with the egr attached and get the aluminum one?

No. The new manifold is a revised model with a revised stovepipe that will not crack the surrounding plastic on the manifold. You can tell if you have the new manifold by the date stamp on top of the manifold. There will be an arrow pointing to the year. All manifolds made on or after 2003 had the revised design, and all manifolds before 2003 will fail, guaranteed. Its only a matter of time.

I'm referring to the lower intake manifold gaskets. You can get revised LIM gaskets as well, as the factory ones are plastic and can start to leak rather early. GM makes a revised LIM gasket for the L36 which is made of aluminum.

Refer to this thread on gmforum.com (formerly bonnevilleforum.com)

http://www.gmforum.com/showthread.php?t=288210

[DevMcLin]

I had done the job once year ago.
My ride

The leak was there but I dont had coolant checked and the all the coolant flush in the engine (oil).
I was asking in another forum but I dont never get an answer because which alu LIM will fit on the L36 engine.

[92 GP]

Sofa, they are not quite like the 3.4's because on the 3.8's you don't have to pull the rockers/pushrods, the 3.8's are quite a bit quicker than doing the 3.4's, however for the 60* engines there is a $20 tool you can pickup that will save you quite a bit of time! It's about a foot long and has a plastic handle with a boxed end to flex the rockers enough to swing them off the pushrods so you can just rotate them then pull out the pushrods, keeps you from having to find the socket for the rockers (13mm 12pt i think?) and having to torque them all back down, etc!