This past year, I had an oil pump replaced in my engine. The failure came at just under 200,000 miles. Dealer diagnosed it as my engine needing my fuel injectors cleaned and the oil screen needing cleaned out. Their diagnoses came after I told them my oil pressure would not stay above 20 lbs pressure. After picking it up and paying a bill well over $1000 for their work, I only drove a few miles down the road before I had no oil pressure at all.

My oil pressure is again starting to fluctuate. This time, the pressure starts out at between 40 and 50 lbs. After warming up, the pressure drops to 40 lbs. psi and remains for a short while. After engine has been running and up to normal operating temp the pressure drops again and will stabilize at around 20 lbs while idling in drive or in park.

My question is, with a new oil pump installed just under 20,000 ago, is it likely the screen in the pickup tub is getting plugged? Or, is the screen above the oil filter the culprit causing my oil pressure drop. I really don't feel the oil pump would fail after such a short period.

I also have to ask, will the oil pressure relief valve above the oil filter cause such radical fluctuation of the oil pressure. Just wondering if it can get stuck open as the engine warms up. It would be the easiest fix and least costly.

 

depends on the oil. Conventional doesn't stay within spec as well as synthetic. Mobil 1 acts different new vs right before the change. If its been used, 60 cold, 40 warm, then in gear parked during winter 30, in gear parked, with ac on (500 rpm idle) 20 psi.

Sounds like yours is fine. Should see how one of the 351W fluctuates in our boats. 80 cold (throughout whole rpm range), 60 warm and cruising, 40 warm idle, and 10 idling after a cruise, (250 rpm idle, pressure will slowly work its way up to 15, sometimes 20 after cooling a bit...) Where as the 351W in our other boat is 50 cold, 50 cruising, and always 40 idling... Don't get it, both are the exact same motor....