Oil Pump Pressure Regulator failure

Dream about your 240's turbo power in this forum.
Post Reply
Dreams of owning a 240!
Posts: 68
Joined: Thu Oct 29, 2015 7:02 pm

Oil Pump Pressure Regulator failure

Post by tuzzio » Wed Apr 18, 2018 1:56 pm

Anybody ever experienced this before?

Long story short. Engine got a rebuild this winter (and no, it didn't blow up so no metal or debris traveled through the pump) and upon my first handfuls of start ups oil pressure was great. Did my first oil change to get the assembly lube out of the oil and upon the next start up immediately after I had 0 oil pressure. I quickly shut off the car for diagnosis. Eventually diagnosis came down to pulling off the oil filter and cranking the car. Wasn't even getting oil to the filter.

Anyways, this lead me to dropping the pan/pick up/ front cover. Nothing was visually screwed up, so I took the pump cover and pick up to work and x-rayed them. Nothing found except the pump cover was a porous casting. Ordered a brand new pump cover and pick up from nissan. A friend took a spare oil pump drive spacer I had laying around and made a tool to bench test the pump with a drill. Same results. Swap the gears from my old pump (I put a new pump in last summer from rockauto) and got it to work.

I went back to the dealer and ordered new pump gears. While I was waiting for those to come in, I kept playing with my "spare" parts. I took all of the parts I wasn't planning on running and got it to pump oil. Now frustrated, the only thing I can think of is the pressure regulator failed to open and circulate oil out of the pump. (atleast, I believe thats how it works)

Its baffling to me that this is even possible, as the FSM states that if it moves freely...its within spec. its not exactly a wear and tear item. its a small piston looking (diaphragm, if you will) with a spring.HOW DOES THIS HAPPEN BETWEEN OIL CHANGES.

Post Reply