Strange oil pressure after I frame

[Rawze]

(12-15-2024 )Nater1977 Wrote:  So I got to my shop this morning went through all the bearings thank gosh they’re all standard that rules that issue out.

I assume you meant the ones that came out... that's good. Having an alternate bearing in a CM871 is about a 15% chance or so. Less for newer engines. but still not a guarantee.

mahle (germany) overhaul components are fine. Athough personally, I would have measured all of them, each in several places, with dial indicator before putting them in .. Mahle is the supplier for cummins themselves.

BTW: 28 psi is normal pressures at idle ONLY AFTER THE OIL HAS WARMED UP FULLY (215+F), but not so much so while the engine/oil is still at room temp. - What are the pressures with it fully warmed up, oil temp above 218+f?.

Are you sure you don't have a shimm upside down (or swapped from left to right side) between block and pump, at the oil pump?.

Also, 60-psi, I think is the blow-out safety-valve pressure at the top-left side of the oil filter housing. If the pump is making too much pressure due to someone adding shimms to its regulator incorrectly ... or due to a blockage of return oil (from the head, thru and behind the front gear cover), then this valve could be triggering, dropping pressure off after the valve opens, until you shut engine it off again and it resets.