69 Camaro with TH350 transmission. Leaky trans pan gasket. Installing new cork gasket. What's the best sealer to use? Is the Permatex automatic transmission RTV sealant (81180) any good? Or is something else ok? Appreciate any advice

 

Permatex should be fine just don't over tighten the pan and crush that cork gasket.

 

The first thing to do to prevent leaks is NOT use a cork gasket, anywhere, ever. Use one of these, without a sealant crutch:

 

Definitely better,I sometimes wonder why they even still make cork gaskets,cheaper I guess.

 

I always thought the rubber gaskets were better, however i've installed two in the past few months and each time I get leaks. I know the issues are clean surfaces on pan and transmission, pinging bolt holes on the pan, making sure the pan isn't warped or twisted, make sure it's flat on a flat surface, good sealant coverage, adequate drying times. I've worked thru all those issues and still come up with leaks right at the pan. Made sure the cooling lines weren't leaking and there weren't any cracks etc. Clean dry paper towels are very useful for checking for leaks. Not sure what i'm missing. Since I already wen't thru two rubber gaskets figured I wouldn't be any worse off trying a cork gasket if follow all the advice. This time if I still get a leak i'm going to the local transmission shop. Local guy, not some chain shop.

 

Check the pan for flatness, The pans tend to get over tightened and they will bulge at the bolts. On most older cars I have to get out a body hammer and straighten the pan.

 

It's not a chrome pan, is it?

 

not chrome