I took my Perkins 4.108
out and had it rebuilt. I built a crib on a small boat trailer
and ran the engine there before bringing it back to the boat
. I didn't have but 10 psi on the oil pressure so the engine went back to the shop.
I can tell you that the pressure relief valve is responsible for 90 percent of the oil pressure. Too little spring force and you don't have enough pressure anywhere in the system.
I don't have a theory on how it could be too high though unless the needle valve got stuck somehow and is not relieving at all. It was just a spring, needle valve and some washers. I guess you could have a really really bad oil filter
I have small industrial pressure gages installed on my engine. I've always felt that the pressure indication is a bit of a false thing since you are not really reading the back pressure on the oil passages as much as you are looking at the performance of that pressure relief valve. Oil sending units aren't exactly calibrated instruments either, so I like the manual steam gages.
What does it look like under the valve cover? Are you getting oil up there? If the pressure relief valve is stuck I'm guessing it is spraying oil like a pressure washer into the valve cover. Other than going to the head
, it mostly goes through the crankshaft oil passages and bearings. The rest of the lube is splash and drip on the way back to the pan.
As an aside or another data point, after my rebuild
, I switched to synthetic oil. The engine did not like synthetic at all... oil consumption
went way up, pressures where all over the place. I went back to Rotella 10W40 dinosaur blood and all is well in the kingdom once again.