Thermostat gasket leak

[cudabob496]

How do you keep the thermostat gasket from leaking on a 440. I just replaced the thermostat. I tried one gasket, and now am trying two. Maybe I'm buying the wrong material type of gasket (from Napa). Or do I need to heavily torque the two bolts? thanks

[MrChemist]

Prep your surfaces well (key to a good seal), use ONE gasket, put permatex on both sides of the gasket, torque down and wait a few hour before adding coolant and starting.

[cudabob496]

That's my problem I think. I didn't wait a few hours before filling, even though I had used permatex. thanks

[moparmarc]

I like to tighten it down, let it set, then torque it down. Seems to seal real well.

[Dick]

Make sure the mating surfaces are clean of old gasket and sealer. The water neck might be warped from being overtightened. You can check it for flatness by rubbing it around on a hard flat surface. High spots will darken. Repeating the procedure over a sheet of emery paper will clean it up. Make sure to wash thoroughly before installing.

[wilks3]

This is what I did. Go to NAPA or any parts store, ask them to get you the rubber seal that fits around the stat. It has a groove on the inside of the quad ring where it will fit in. A quad ring is "square" where as a "O" ring is round. Take your housing and stat with quad ring on it to a lathe. Ya I know, not everybody has one, but somebody should know somebody that has one though. Put housing in lathe and cut it so the quad ring fits in snugly from a diameter stand point and deep enough so quad ring goes in 1/2 its thickness. I hope I explained that right.....anyway you now have made a modern housing that uses a quad ring to seal it up. Works like charm. It takes less time to cut housing than to chuck it in centered and square.

[cudabob496]

thanks for all your wisdom guys! I'll try what ever is necessary.

[chitown hustler]

What kind of thermostat housing do you have ?

I,ve seen many orginal housings with heavy pits from corrosion that would weap fluid out .
And lots of those fancy cheap chome ones seem to leak no matter what.

Just something to look at if you haven,t already as there,s no reason it sould be that hard to seal if your housing is good.

[Thrashard340]

The factory ones seem to be the best...I haven't had any luck getting the aftermarket chrome ones to seal.