Quote:

There should be a breather opposite the PCV - regardless of the side it's on. But - what you're hearing is not crankcase pressure as one might think (bad stuff). It's escaping pressure from a cylinder that was sealed when you shut it down. No big deal.



The hissing stops as soon as I crack the filler cap. I definitely need a breather there.

So is the pressure just slipping passed the rings of whatever piston moves up on the compression stroke after the engine is shut down?