Thermostat Housing Leak .... From housing to engine block .... Replaced gasket 3 times now, and for some reason I can't get it to seal. Original gasket was a rubber seal .... AutoParts are now selling these composite gaskets. Some thoughts or advice please...?

Just use a bead of permatex "Gasket Maker", comes in a tube and once dried ((24 hrs), it will not leak.

Make sure the gasket surface area of the thermostat housing is perfectly flat, not warped. File and or sand flat as required.

[This message has been edited by Patrick (edited 11-09-2014).]

quote Originally posted by 84 Fiero SE: Thermostat Housing Leak .... From housing to engine block .... Replaced gasket 3 times now, and for some reason I can't get it to seal. Original gasket was a rubber seal .... AutoParts are now selling these composite gaskets. Some thoughts or advice please...?

1. Two styles of Tstat housing.
If has rubber "O-ring" then FEL-PRO Part # 35062 and others Will Not Work.

2. O-ring then you can try using only RTV but you need:
a clean and dry housing and block. No coolant dirt or oil at all on the parts. Use brake cleaner for final cleaning step.
RTV needs time to set and "dry," like 2 days or more. You can not fill the system while the RTV cures.

I made a gasket using FEL-PRO Part # 3018 Cork-Rubber Sheet.
inside diam is same as FEL-PRO Part # 35062
Outside diam fit the housing hole.
End result:


Then I use small amount of RTV, both sides, and let dry 1-2 days. (Read full dry/cure time of product, set time is meaningless here.)

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(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

quote Originally posted by theogre: "Gen 2" housing that uses O-ring gasket is very hard to warp etc. If you bend the heavy flange then you likely need another housing.

Ogre, I was having a memory malfunction and was thinking of the thermostat housing on the 2.8 engine.

Permatex makes a water pump gasket sealer that comes in a small tube. Have only used the full gasket with the sealer and they always sealed perfectly.

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Guys, Thanks for info. I'll give it another try this weekend.