Tobin,

Having looked at your photos, I would say that the oil pressure relief piston
is hung up on something - probably debris. To first glance, the hole in the
exit side is just fine. The hole on the 36 mm pump assembly is twice that
size. The pattern that the oil pump gears are cutting on the end face is
disturbing. Looks like there is galling there. Or you are running valve
grinding compound there.

A good machinist can easily remove the back cover of the oil pressure relief
valve to clean things out. The spring pressure reset is not a problem in that
there is an inner land to stop the retainer at the right compression
distance. The staking of the retainer is serious. There are many cases of the
assembly being blown into the crankcase with an improperly staked retainer.

Barring the success of such a solution, I have several diesel pickup spares
and could forward one, should needs require.

Frank Grunthaner