M35A3 very high OIL PRESSURE

Heavy D.

Newport News, VA
Noticed high oil pressure at approximately 65 PSI start up while idling on a 90 degree day, under load while driving the stock gauge pegs out.

Today I hooked up a mechanical gauge and got about 55 PSI. during revs up to 2600 rpm it reached 100 PSI under no load. I haven't tested it while driving but I assume it will give me extreme readings as well.

Now that the sending unit is crossed off as a culprit does anybody have any ideas what I can do to further trouble shoot? as I understand it these kinds of pressures indicate restricted flow and could be very bad for the engine.

Please Help!


Feo, Fuerte y Formal
Supporting Vendor
Mason, TN
Replace your oil filter first. If it doesnt change then the culprit is more than likely a stuck high pressure relief valve inside the pump. Especially if it's the old style pumps. The 3116s had that issue with em.

Another issue is a blown gasket between the oil cooler and the filter base which is allowing oil to bypass the filter causing higher pressure or a stuck oil filter relief valve

As far the relief valve goes. Drop the pan and it's under the Allen head screw showing. You can clean it and put it back in as there is no replacement for it. you would have to swap the oil pump for the newer geroter Pump

Max pressure at engine full load should be 88 to 90psi
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