Low Oil Pressure at Idle

Sh0velMan

Hey, I replied to your Facebook message too, but I'll post here for posterity's sake.

There's absolutely no way that oil pressure is being affected by anything related to your catch cans. Even if they were plugged closed you'd have the same oil pressure, air is compressible, oil isn't, and a a pump like an oil pump thrives on back pressure.


Does the gauge show pressure at start up that falls off after warm up? Are your "under load" pressures identical to what they were before?


It sounds to me like a conductor has gone high-impedance on the sensor circuit, causing an offset that drops to zero or near zero once you get the normal pressure drop as the oil thins out. Was ANY modification done to ANY wire related to the sensor or to anything else in the same harness?


Is it possible that you jiggled something loose or perhaps inadvertently got a harness somewhere where it got heat damaged? The insulation on the OEM wiring isn't particularly high temperature, exhaust parts or gasses will melt and burn it in short order.


This is on the assumption that you are piggybacking the OEM sender for your external gauge. If you have TWO senders on completely different circuits both agreeing that you have low pressure, it's hard to argue that there isn't a real issue.


If your external sender is on a sandwich plate, it's going to be on the part of the oil circuit that is going into the oil filter, if you have low pressure right there at idle, but normal pressure at speed, I have to think the pressure regulator in the pump is faulty in some way. I believe it's just a spring-type regulator, and if the spring has failed it will be venting most of the flow back into the crankcase, at speed the pump will have the flow to overcome that, at least partially.


My advice in the immediate sense is to not go above 4K RPM unless absolutely necessary, I'm going to check the FSM and find an oil circuit diagram. I'll post what I find.

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