Going to replace my housing gasket tomorrow. Should I use a smear of RTV on both sides of the gasket, or just make sure both surfaces are clean and install the gasket dry?

Old paper gasket soaked through after 4 years. Hoping to avoid that from happening again.

Make sure the thermostat housing flange is flat.

It might be regarded as "old-school" now, but for 40 years I've used Permatex® Aviation Form-A-Gasket® in situations like this. I'd put on a very thin layer on both sides of the gasket.

[This message has been edited by Patrick (edited 07-20-2014).]

Hey thank you. I did use a thin layer on both sides this time. Hope to get more than 4 years out of this one.

There's a better gasket available.

I found Fel-pro PN 35595 for GM engines has a nice rubber ring embedded in it.
The bolt holes are a perfect match - only need to elongate them slightly outward.






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Calgary time/temp

3.4L Supercharged 87 GT Click me
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[This message has been edited by fierosound (edited 07-22-2014).]

quote Originally posted by Patrick: Make sure the thermostat housing flange is flat. It might be regarded as "old-school" now, but for 40 years I've used Permatex® Aviation Form-A-Gasket® in situations like this. I'd put on a very thin layer on both sides of the gasket.

Yup... just enough to seal any imperfections. I have also used Permatex high tack sealant.

Thanks fierosound for the gasket idea. I tried to find your original thread to post this, but I can't find so it. +1 to you sir.

quote Originally posted by fierosound: There's a better gasket available. I found Fel-pro PN 35595 for GM engines has a nice rubber ring embedded in it. The bolt holes are a perfect match - only need to elongate them slightly outward.

Fierosound, this is an excellent idea and upgrade. Thanks for sharing...

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fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

"Paper" failed then likely Tstat is not flat or dirty etc or used wrong gasket.

Many "paper" and cork gasket use High Tack but Many Tstat housing have problem from over torquing the bolts etc.

RTV takes 24hr or more to full cure. Cold weather can take days to cure. Freezing weather might many can't cure or takes week or more to cure. Dry and not sticky IS NOT full cure. You can't load coolant or drive until then.

RTV hate oil/grease, coolant, rust, or dirt on pieces to seal. Best last step is brake cleaner.

Above work on v6...
L4 have two types. If L4 Tstat housing have thick flat flange then won't work and you can't get new silicon "o-ring." I made one from flat cork supply, apply w/ little RTV and then let RTV to cure for 2-3 days.

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