Oil Pressure Relief Valve

Dec 24, 2003
Can anyone advise me on how to test the spring in the oil pressure relief valve that is in the timing cover ?

Another question is: How many shims were fitted originally at the end of the spring when new ?

What is the procedure for setting the oil pressure relief valve up after disassembly ?


According to my manual the pressure relief valve is originally setup
at the factory to prevent oil pressure from exceeding 45-55 PSI. Evidently using whatever number of shims required to do so. The valve isn't suppose to need any maintenence (although in a previous post someone said that they had found theirs stuck). I quess you'll just have to make sure its free, stick it back in and test your oil pressure.

justa thought,
Jul 18, 2004
I was the one that found the piston in the valve stuck - solid! :shock:

Mine was shimless btw ~ no idea if that was original setup, but considering the state it was in I would guess it hadn't been touched in 35 years.

I was thinking of testing it with my aircompressor by threading it to a section of pipe and increaseing the pressure until it blows off... but I never got around to it. I plan a bottom end rebuild for next winter so I will get into the nitty gritty then.

I never did find out if the torque spec listed was for the valve to case or for the dome nut to valve.

Let me know how you fare!


Nov 20, 2004
Country flag
RGM Motors in the UK sell an oil pressure test gauge kit (RGM item 908B).
This consists of a gauge, a short length of pipe and an adaptor that fits alongside the rocker feed pipe connection to the timing cover with a double banjo bolt and copper washers (also supplied in the kit) so that the rocker feed isn't disconnected during testing.
I bought the gauge kit and shims because I also found that my own pressure relief valve had no shims fitted, although when I tested the oil pressure I found that the valve was opening at the correct pressure.
Not only is the gauge useful for checking the relief valve it can also be used for general oil pressure checks.
The gauge isn't really meant to be permanently fixed, just for test use.
Dec 24, 2003
Thanks for the replies.

I wondered if you could test the spring like a valve spring ?
The easiest way would be to just buy a new one I guess.

There were no shims in this setup......but the domed nut & other nut have been butchered. It has been messed with........

I have fired the 850 engine up, started second kick :D but I really wont feel at ease until I know this relief valve is correct.

The oil appeared to be returning ok into the oil tank, just like any other I have seen.

So, to be certain I guess I will have to find a longer banjo bolt & hook it up to an oil pressure guage I have had lying around since the pyramids were built.