1990 T4R - Low Oil Pressure.

[Ceehris]

I own a 1990 4 Runner SR5 (3.0L) 290000 kms
I have good oil pressure when cold, the more the engine warms up the lower the oil pressure gets, if you floor the gas pedal before shifts the oil pressure doesn't rise, but when your in park and rev the engine at a constant med-high rpm. the oil pressure rises to normal pressure. Anyone have any advice? I'm using 15w40 for oil, I was running 10w30 but I seem to get better oil pressure with the thicker weight oil.

 

[CJ3Flyr]

I own a 1990 4 Runner SR5 (3.0L) 290000 kms
I have good oil pressure when cold, the more the engine warms up the lower the oil pressure gets, if you floor the gas pedal before shifts the oil pressure doesn't rise, but when your in park and rev the engine at a constant med-high rpm. the oil pressure rises to normal pressure. Anyone have any advice? I'm using 15w40 for oil, I was running 10w30 but I seem to get better oil pressure with the thicker weight oil.

It's old and tired, the oil pressure is going to be lower. 15w-40 may not be a bad choice.

I would suggest getting a cheap ($20) mechanical oil pressure gauge and install it temporarily for testing purposes. It sounds like the oil pressure sending unit is lagging. Until your sure you of your pressure (in real numbers as compared with the spec) and the pressures' behaviour it's hard to know what to do. Stock engines can do ok on surprising low oil pressures; idling at or above 15psi and then 10psi/1000rpm is enough if everything else is ok.

Is the engine mechanically quiet? I understand you probably have some valve tick I am interested in rod knock/bearing knock.

:cheers: