Packard Forum Index » Pre-War (1899-1942)

I am putting the intake and exhaust manifolds on and realized a number of the holes or open to intake and/or exhaust. What do you guys use to seal the engine side threads?

It's a 1941 super 8.


Thanks in advance!

Whoopsie - just checked again and they appear to be all to the water jacket.

I'm assuming a high temp silicone is the answer - please confirm

Not at all a fan of silicone gasket sealants. I've always used Permatex #4 or gasket shellac for threads that penetrate into the water jacket.

I would suggest a high temp thread sealant that is thinner and will seep more into the threads rather than a thicker RTV silicone that may sit more on the surface. Permatex makes some thread sealants in different temp ranges that are available at most parts stores. Here is one of them. sealant

All the head stud holes go through to the water jacket, I've done many many engines and never used any sealant and never had a leak. Same for manifold studs.

CORRECTION : I NOW RECALL A FEW TIMES A SINGLE HEAD STUD LEAKED. I REMOVED IT AN PUT OLD FASHIONED PERMATEX WHICH DID THE TRICK. BETTER THAN HAVING HAD TO DO SEVERAL THOUSAND "JUST IN CASE"

I actually have a tube of Permatex High-Temperature Thread Sealant, but for some reason I *thought* it could only be used on tapered thread. I use it all the time for nptf fittings, and it works awesome. I'll go ahead and use that.


Thanks for the responses guys!