Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Oil Pressure pulses up and down

318 Dodge Ram Engine with 212K miles. Oil pressure is 40-50 PSI@3500 RPM, but mechanic says pressure pulses up and down, but he can’t explain why. Anyone know why? And, he says it has engine crankcase blow by at valve covers. Can this engine be salvaged?

It’s normal for oil pressure to vary depending on engine RPMs (faster RPMs = higher oil pressure)…do you mean it’s “pulsing” while at idle?

Blow-by is an indication of worn piston rings, which wouldn’t be a huge surprise given the mileage. Of course, it might simply need new valve cover gaskets if the only thing he’s going on is oil from the covers. Not the clearest description of the problem. What sort of symptoms are you having?

Trying to determine if engine is still OK. Have to replace the transmission, but not sure that engine is good enough to warrant investing money in the tranny. Compression tests range from 150PSI high to 100 PSI low with the rest inbetween. Oil pressure tests 11-12 PSI @ idle and 40-50 PSI@ 3500RPM. The “pulsing” occurs at the 3500 RPM. Runs ok though. Worried there’s a major repair waiting in that engine.

Don’t we all worry there is a major repair lurking with our engine. You can do the maintiance,never abuse your engine and things still go wrong.

Just one example a co-worker had the rod cap bolts break on one rod of his FORD engine,who would expect a problem like this?

100 PSI is rather low, and you don’t want that much variation between cylinders for sure. However, the oil pressure numbers look good and as long as it’s not hitting zero regularly, it should be okay.

It does have a lot of miles on it, so I don’t think there’s much out-of-the-ordinary happening by this point. It could probably stand a rebuild, but only if done properly AND you’re willing to drop the coin on doing that.