Thread: 2002 Grand Prix SE--Is my lower intake manifold gasket failing?

The brown sludge is simply a result of dex cool. Mixing the two will cause lots of sludge but it seems you had it flushed soon enough. Even dex cool alone over a decade will cause some sludge from being exposed to air. If that little bit is all you saw I wouldn't be worried. If it doesn't overheat, and if you add coolant and it doesn't drop I wouldn't be worried about the intake either.

My old ones were a bit worse lol. I flaked nice sized chips off mine before replacing them

Being a 3100, I would automatically say yes on the intake gaskets. They are maybe a bit more common than the 3800. Make sure you get the metal frame gaskets. And.. keep the pushrods in order, they are different sizes between exhaust and intake.

Originally Posted by 02NavyBlue

The brown sludge is simply a result of dex cool. Mixing the two will cause lots of sludge but it seems you had it flushed soon enough. Even dex cool alone over a decade will cause some sludge from being exposed to air. If that little bit is all you saw I wouldn't be worried. If it doesn't overheat, and if you add coolant and it doesn't drop I wouldn't be worried about the intake either.

There was a lot more sludge when I first removed the radiator cap; the entire inner metal "cup" on the underside of the cap was filled with it, and then some. I do check the coolant level regularly, and it seems to be holding steady now--I did have to add more this past winter, but that was one of the longest, coldest, and most brutal winters we've had in a LONG time. My power steering was also leaking pretty badly then, but it's mostly fixed itself now (I think the PS cap is leaking) I'm sure having to start my car in sub-zero temperatures and letting it warm up for 15+ minutes on at least a half-dozen occasions didn't help, either (I park outside).

It's never overheated, but if I'm idling with the A/C off, the temp gauge will slowly drift from ~185F (1/4 mark; where it normally is) all the way to 210F (1/2 mark), and then go back down slightly. If I start moving again and/or I turn the A/C on, the temp gauge will go back to ~185F. I've noticed this ever since I got the car 2 years ago; is this normal?

Originally Posted by lewis1952

I would keep an eye on those strut mounts. That's a lot of rust.

Not nearly as much rust as the underside of my car. One of my parking brake cables broke because of all the rust under there, and there's an actual rust hole under the left rear door (due to a salt truck going by me the other way last winter, and not being able to wash my car for 1-2 weeks afterwards). But compared to most of the other '97-03 Grand Prixs and Buick Centuregals I see around here, my car isn't that bad.

Originally Posted by BillBoost37

Being a 3100, I would automatically say yes on the intake gaskets. They are maybe a bit more common than the 3800. Make sure you get the metal frame gaskets. And.. keep the pushrods in order, they are different sizes between exhaust and intake.

If only I had the time and money... I'll probably wait until I notice things getting dramatically worse. I do check all the fluids regularly just in case.

Thanks for the quick replies!

Originally Posted by Teraforce88

It's never overheated, but if I'm idling with the A/C off, the temp gauge will slowly drift from ~185F (1/4 mark; where it normally is) all the way to 210F (1/2 mark), and then go back down slightly. If I start moving again and/or I turn the A/C on, the temp gauge will go back to ~185F. I've noticed this ever since I got the car 2 years ago; is this normal?

Yes and no. It is normal because many will do this in traffic and 212 is where the fans come on. No because many systems in good shape won;t reach that temp. But that's still nothing to be worried about, 210 isn't that hot.