Posted 8/6/2026 15:33 (#11720676 - in reply to #11720527) Subject: RE: 855 Cummins losing oil pressure
NY
I've had a pressure relief get stuck on one and it would do the same thing. Normal pressure when oil is cold but once it thins out, the relief didn't move to keep pressure up because the o-ring was old and sticking. Cheap thing to try, bottom of the oil pump on the front left of the engine. I just put a new o-ring in it and that's all it took.
855 Cummins losing oil pressure
