Blackbelt

So I have a coolant leak in my motor... (98 GT, stock motor NPI). I thought it was partially the NPI intake, then I noticed some antifreeze residue on the thermostate housing. I decided to replace the thermostate, and O-ring. still leaks.. should I get some Gasket maker.....?

Just wondering what else I should check on? I haev some fluid on the front cover of the motor, and on the pulleys.... could that be from the thermostate houseing?

MaxxRPM

Does the thermostat itself sit down inside a plastic manifold or is it aluminum? If your intake manifold is still all plastic most likely it cracked somewhere around the thermostat seat and if it is, it's time for a new intake manifold. Exact same thing happened to me on my 96..........evidently this is a very common problem with the all plastic intake manifolds (96-01).

wcgman

Very true...its that crossover pipe on the front of the manifold. Plastic ones crack.

slipperman

I have a crack with the later "aluminum crossover" type.
If you look, the plastic flange of the manifold extends beneith the aluminum and between the thermostat and the cylinder head.
I'm not sayin' that's where your leak is from, but mine was.
If it's coming from the thermostat housing, you need to re-check the o-ring and it's mating surfaces. Smoother is better.

Blackbelt

the thermostate housing is aluminum... i am going to be checking all over the darn thing this weekend.. costing me a small fortune in antifreeze.. lol