LostChord
Well-known member
Despite my esteemed colleague Smeggman's 4 doors of guessing.....none of which would be my go to (although the fixes for Morty's guesses are cheaper than my diagnosis), here's my best guess.
Hadn't you been having cooling system pressurization issues ?
Sounds like #4 cyl of head gasket to me (hissing sound from back of head).
Cyl is under 385-400 psi and higher when under load ie boost. When it's under boost and leaking worse than @ idle you will get incomplete combustion which results in white smoke out tail pipe. Oil out the cap is result of pressurizing oil gallery/ crank case
That is my arm chair diagnosis based on descriptors.
Thanks Doug - great memory. Yes, I was having cooling system pressurization issues, but that got resolved in short order by Safari, and thankfully, has not been an issue since.