High oil pressure on a truck that has sat for a long time

Took my Deuce out for a couple laps around the neighborhood today. Over the last 5 years, this truck has probably been on the road 2-3 times for a total of 45 minutes. So it sits a lot without running. Oil pressure has always been good but today I noticed it was high, looking above 90 on my 120 psi gauge. Any well-known reason for this? I'm pretty sure I've changed the oil filters at some point but it's been a long time.

Edit: I think maybe it's just a gauge problem. After it sat an hour, went out and started it up. At idle, oil pressure slowly climbed from 0 to 110. Let it idle a short while then shut the engine off, but left the aux switch on. The oil pressure stayed right at 110 for quite a while. I never saw it move down (which it should, when the engine is off but aux switch on I assume).

G'day everyone,.....




Sounds like the bypass valve is stuck.

I'd say since its been sitting so long oil has dried and gummed up the valve and now its jammed.

Just my thoughts.




Aussie.

Didn't even know it had one but looking at the TM it looks easy enough to remove and check. No info about cleaning it but hopefully that'll be the way to go. Looks like the "Gasket" is a simple O-ring. Thanks!

Looking at the TM and then going out and looking at my engine...I can't find it. Any help with a pic?



Is this it? (circled in red)

Here's a couple of pictures showing it's location and what it looks like.

View attachment Scan0174.pdfView attachment Scan0175.pdf

Hmm, that’s on the opposite side of the engine. I think the two of you are talking about two different things. Of course an oil pressure regulator sounds like it might be related to my problem though!

So I will check out the oil pressure regulator also, but can anyone confirm I've circled the correct plug for the oil pressure bypass valve on the steering column side of the engine?