Low oil pressure after shim

[pearce trucking]

(05-15-2018 )Brock Wrote:  No I didn't find one, just assumed I could. I'm questioning the possibility of it being the spring because when I went from a 3/4" shim down to a 1/2" shim, I should have seen a pressure change and I didn't. If the spring were weak, it would still fluctuate with the amount you shim it.

So your pressures are the same before and after? If you can find someone who has a spring compression tester (or buy one) you can get a definitive number on the strength of your spring. i believe the spring is 3.716 inches long. Assuming it was weak before shimming, the shimming has made it work harder in the interim, weakening it more. Absent new engine damage, there really should be a pressure difference between .5 and .75 shim.