Coolant Loss - Lower Intake, Etc?

[jsoluna]

Hi guys,

I'm working on a 2000 Bonneville, but wanted some info from this forum since it seems there's way more owners with the 3.1/3.4 engine. This particular problem seems to be a common thread among this engine platform, so I hope you excuse me from posting in here as well.

Coolant loss? Yeah yeah yeah I know! It's leaking from the lower intake manifold gasket for sure, verified this today - could see it dripping from the passenger's side down the headforums, water pump, and down the side of the block onto the ground.

I've been doing some research before I divine in, though, and although I knew GM had a problem with lower intake manifold problems I just found out that they also had a problem with their plastic upper intake manifolds melting!

What's the easiest way to verify if I need a new intake along with a new lower intake gasket for this 2000 Bonneville? I was reading that the melted upper intake problem was fixed in 1999 for the 3.8 engines. (I have a vague understanding of the problem, but I think it has to do with the EGR tube being routed through the plastic plenum) Is this true?

Thanks guys, good to become a member of the forums!


Justin

 

[Goatman]

I believe there is a distinguishing mark on the intake thats a give away if it is an upgraded intake or not but you can check with your local dealer for more info..
the plastic intake plenum was a 3.8l item if I remember correctly ...
I do know they had issues with lots of the plastic intakes on the 3.8s (buick based engine)

but I think the other engines had aluminum intake plenums (3.1-3.4)..
also watch out for headgasket issues (on the 3.1-3.4) if the problem has been let go too long they seem to blow out also (usually shortly after) you do the upper and lower intakes ..

 

[jsoluna]

I'll check with the dealer and see what the deal is with the updated intake, I didn't realize that the 3.8 was different in that way.

Thanks man.

 

[J Wikoff]

The 3.8 and 3.4's share very few, if any parts. They are setup entirely different.