Porsche Enthusiasts Club Forum

Other than replacing the external o-ring seal, can the cylinder head relief valve be serviced? (this is a 1989 2.7).

How do you check if it is working correctly?

Many thanks,

Dave

You mean the oil pressure relief valve?

I don't think it is serviceable, even though it looks a pretty simple item. When it isn't working, the results can be quite spectacular...
Stuck open, no oil pressure
Stuck closed, litres of oil gushing from your (now loosened) oil filter

Do you have any particular reason to suspect it is faulty? I presume you've seen the price of new ones...

Hi Dave, while I was looking for info on the 16V version of this valve I came across this thread on a USA forum:

http://rennlist.com/forums/944-turbo-and-turbo-s-forum/622859-possible-to-test-oil-pressure-valve-in-cylinder-head.html

A lot of folk get this confused with the OPRV fitted to the oil cooler/filter housing, but this one is the relief valve fitted in the head to regulate the oil to the tappets and act as a one way valve to prevent drain-down when the engine isn't running. Not all 944s have the valve, some have a simple ball and spring arrangement.

Hope that gives a bit of info...

That is exactly it Brett. Thanks for the link, it's really helpful as I haven't been able to find anything on it so far. Now I see how it works.

Ultrasonically cleaned it, already got a new seal, will check it works, and put it back. Got taken out when I stripped the head for welding, guides and skimming.

The oil cooler OPRV got stripped and new seals when I replaced all the oil cooler seals (along with many other seals!)

Finally putting everything back after months of work