Michael Stephenson

I have the dreaded “moan” which means that I need to change the O-rings in my oil pressure relief valve.

I have the O-rings and a printout of the PET page which shows the exploded view. From this diagram, it looks like the valve is located somewhere near the oil filter. However, the Porsche manual says to remove the cylinder head cover to get to the “pressure reducing valve”.

So, the question is: Where is the oil pressure relief valve and what is the best way to get at it?

Another question: How important is it that this problem be rectified – will this maoning cause engine damage?

Thanks in advance.

Tom Pultz

Michael. I've had this same moaning since I bought my car in 1997... and I'm getting pretty tired of it so I think I'll do the same change.

There's actually an updated oil pressure relief valve, part no. 944-107-035-02 that was fitted to engines from 42L 05160. It has offset relief bores and this is supposed to eliminate the droaning/moaning in the 1600 rpm area. Unfortunately it's a $200+ part. Changing the O-rings may help, but it might not eliminate the problem.

It looks like the valve is just under the oil filter mounting area and it scews into the right side of the engine crankcase.

Michael Stephenson

Thanks for the reply.

I guess that if yours has been moaning for several years, then it is not something that will self-destruct the engine.

I am assuming that my engine has the original relief valve and I got two O-rings of the same part number as well as a crush washer. I do not remember the part numbers, the paper work is at home.

If the O-rings do not cure the problem, I will tell inquiring minds that it is an oil delivery performance modification.