944S head check valve seals
 

My 944S engine is almost done, but before I install the cams and valve cover, I want to replace the O-rings on the check valve. I cleaned the valve with WD-40. Even though WD is pretty mild, I would rather not trust the old seals.

PET does not list the check valve O-rings, and I had Sunset send me their best guess as to the parts. They don't look to be right. Yet people here have posted about finding the correct O-rings.

Does anyone have a receipt around with the correct part numbers? I could probably mic it, but I'd rather try to order something with a part number. Thanks, and hope everyone had a Merry Christmas.

buna-n (nitrile) rubber o rings are what you want - they are usually black. If it comes down measuring them. I just cleaned mine up and re-installed for what its worth...

I just compared my O-rings to ones in my generic pick-an-O-ring box and got ones that seemed to fit well. The engine had good oiling to the top end after it, not sure what problems a not-perfectly sized O-ring can cause other than possibly letting oil bypass the valve.