I have an Edelbrock Air Gap intake manifold and have a persistent leak at the thermostat housing. I'm using one of the those FelPro blue gaskets.

I have the same manifold with a billet housing with an o ring. Has not leaked a drop to date...

I had a persistent leak there, too.

Finally I got it to stop leaking by mildly scuffing up the aluminum surface with some fine autobody sandpaper. Then I used a Spectre Industries brand 2 piece Thermostat Housing with an O-Ring gasket (dry-no sealers or such.)

KDADDY79; did you use only the 'O" ring; that means no gasket?

Yup. Just the O-Ring and nothing else.

 

What kind of t-housing is it? Stock aluminuminum, or an aftermarket chrome jobbie?
For stock housings, they must be really clean, and flat...the manifold too. Any irregularities, corrosion, or pits can be the source of small leaks, as can porosity.
If it's of of them fancy chrome jobs, the only way to keep that turd from leaking is to grind/file all of the chrome off o the bottom, where the gasket sits. No amount of sealant, or any trick gasket will truly stop it from leaking if the chrome is still on it. Chrome is too slick for anything to adhere permanently to it, and fluids will seep right between the gasket and the chrome surface.
Even the o-ring style chrome housings will eventually leak, once the o-ring shrinks from age/heat.

Check your housing carefully for cracks around the bolt holes, too....

hth


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