I had to clean up and paint the heater box, and the old gasket was shot in a few places, along with there being rust under it I wanted to fix. So the old gasket was removed. Is a new gasket available or should I just use rtv?

 

Use 3M strip cauk. It should be available from your local auto body supply store. Thats what the factory used on cars that didn't use a foam gasket.

 

JamesC

 

What would happen if you didnt use a gasket at all?

 

It would leak, causing an already inefficient system to be more so.

JamesC

 

if you caulk it, it will be a beotch to get off later. they make a foam rubber weatherstripping for windows and doors, that is what i used and its great. I bought some about 3/4 wide and 3/8 thick. Still have some left
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Once every 20 years or so shouldn't be a problem .

JamesC

 

In reference to the no gasket, the couple spots where mine was completely flattened and not doing it's job, looks like water was dripping inside and rusting.

Thanks for the suggestions. I think for now I am just going to use no gasket. I want to take it off again in the spring to paint it nicer lol. The car is going into storage for the winter soon, and I mostly just need the firewall sealed as best I can from mice