buickanddeere
Super Member
There is delta p across the relief valve, as there should be, because the engine cannot take all the oil the pump puts out. It's supposed to be that way.
if the bypass valve doesn't open the filter can act as a restriction.
Has oil pressure been measured at the pump discharge prior to the filter ?
A cam bearing can walk out of place and spill a lot of oil. Doesn't immediately make a bad sound .