I need some help. I am in the process of reinstalling my rebuilt 1970 302. I can't get the thermostat housing to seal. I have tried with and without sealant. I thought the housing may be too pitted, so I replaced it and have tried 2 different gaskets, with and without sealant and it continues to slow drip from the bottom.

Should I try just using the gasket maker/sealant and no gasket? Any other suggestions?

I always make sure that both surfaces are perfectly clean and dry before reinstalling.

 

Are you sure it's not leaking from the bottom of the hose where it attaches to the thermostat housing? That would give the same result.

Or check for grooves/pits on the face of the manifold.

 

I finally realized that my thermostat housing isn't leaking from the gasket, but from one of the bolt holes. I tried plumbing tape on the bolt threads and also using a little gasket sealant on the bolt, but it still drips. Anyone have any other suggestions?

 

They have tread sealant.... Not sure if its any different then the tape or gasket sealer

 

R u sure it's not the by pass hose leaking and if it isn't leaking I would check if the manifold and put a straight edge on it

 

The gasket it's self is not sealed right if coolant is coming out a bolt hole!
There should be no coolant in the bolt hole passages.
Put sealant all over the whole gasket on both sides around even the bolt holes, and especially around both coolant holes!