what is a correct oil pressure reading on IH Super M?

Anonymous-0 · Jun 27, 2012

recent tuned up, valve job, good compression super M with SAE 30 in there. starts nicely and idles at high (close to 75 psi)oil pressure. Under load, working and hot the pressure drops to mid guage. Then later on, lower than mid guage (like 3rd hash mark) Do I have a problem>? how low is too low? should it remain steady at idle and under load, then hot idle?

glennster · Jun 27, 2012

i'd guess the lower plate on the oil pump is worn. pretty common. you will need to drop the oil pan, then pull the lower cover off the oil pump. get a new gasket from the dealer before taking it apart. use a heavy piece of glass and a sheet of emery cloth, then rub the lower cover on the emery in a figure 8 to smooth it back down. good to go.

mkirsch · Jun 27, 2012

Oil pressure always drops as the engine gets warmer.

If you're still at the third tick mark on the gauge when hot, that's pretty good. I wouldn't worry about it.

The Red · Jun 27, 2012

Pat that is normal.

Anonymous-0 · Jun 27, 2012

I have an M and 450 and they both run at 75 psi cold. When they get hot they idle right at 70 psi now I'am running Rotella 15-40 in them.

CNKS · Jun 27, 2012

If it drops below the middle of the gauge, it could be the oil pump as noted, or crankshaft bearings or possibly cam bearings. That does not necessarily mean you need to overhaul it, as it will run for a long time, but if the pressure gets really low, or on the edge of the red zone you might consider it. The oil pump is an easy fix.

pete 23 · Jun 27, 2012

Actual psi is not all that critical. They should run 60 to 70 warmed up under load, BUT, what you watch a gauge for is a change. If an engine has been running that way for many hours it is more than likely general wear in several components. If, all of a sudden you get a change in oil pressure that is when you sit up and take notice. I have repaired many, many oil pumps on M's over the years and the normal problem with those pumps is wear on the shaft just above the gear where it is supported in the housing. That is the pressure point. Luckily though, the housing rarely wore much at all and a new shaft fixed the problem. Normal overhaul procedure was to replace spring and plunger and adjust end play. Had to be careful to get correct plunger though as parts books were messed up years ago and some plungers had a smaller outside dia on the pressure end and that is the wrong one for an M or H. End plates didn't wear much, that is the smaller engines that gave all the problems with that blowing gaskets, warped or worn end plates.

what is a correct oil pressure reading on IH Super M?

Anonymous-0

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glennster

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mkirsch

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The Red

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Anonymous-0

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CNKS

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pete 23

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