Sealing Engine Case Hardware?, To goop or not to goop? Options

[bkrantz]

In theory, sealant on all the mating surfaces for the engine case halves should contain oil and prevent leaks, and (with a couple of exceptions) the design of nuts and bolts, and where they attach, was not intended to form a seal.

But many mechanics swear by applying lots of sealant to every piece of case hardware. Is this overkill? Anyone had good luck lately with just sealant on the case halves?

[ClayPerrine]

I use a thin bead of Drei-Bond. It is the adhesive that Porsche used in the 964 and 993 motors to seal the case halves when new. It never fully cures, and is flexible, allowing slight movement between the case halves. I also put a bead on the base of the cylinders and around the base of the heads on the case through bolts and nuts.

The only leak I have on my 4.0 engine is because of a warped right magnesium timing cover. No leaks between the case halves. And I assembled the case halves with my hand wrapped in a shop towel to stem the bleeding from my cut finger. So I was not as careful as I normally would have been.

People that use a ton of orange silicone on the case halves of air cooled motors piss me off. It is ugly, messy and doesn't seal well. It was designed for use on water cooled motors and is not as flexible as it needs to be for an air cooled motor.