barringt

I've read a couple threads on low oil pressure but no one has really come up with a real answer as to why these engines inherently have low oil pressure. I have a '93 that would show good pressure when cold but not when it got hot. Before I did all of this work I had a good 50psi when cold at cruise and 20 when idling. With the oil temp up around 212 F it would show 20 to 30 at cruise and down in the hash mark area at idle. I started with the sending unit it didn't make a difference. Dropped the pan and put in a new pump and intermediate shaft with the steel sleeve still nothing. The pump was just a normal pressure pump, not a high volume. I would have liked to put in a high volume but people stated that without a high capacity pan the pan would be sucked dry. Not sure if this is true. The car has 139000 runs great, no lifter noise, no check engine light or low engine oil light,the car acts normal. So the question is, why am I still having this problem? Can't be the gauge, cause the gauge would show low pressure whether the engine was cold or warm. The only thing I can think of is bearing clearance, it's gotten too big and I'm loosing pressure once everything expands. What do you guys think? Thanks for reading.

mtwoolford

allow me to relate my own experiences with an lt engine with similar miles.

First I verified everything with a mechanical oil pressure guage.

Yes my engine oil pressure was also very sensitive to temperatures.

First step? admit that the factory recommended oil viscosity was for a new engine with tight bearing clearances.and not an engine with mileage north of 100,000 miles..try a heavier oil.

Drop the pan. Roll in new main bearings; replace the rod bearings with new. This sounds simple, and is, if the original bearings are marked "stnd", .001 os, as are aftermarket bearings, but unfortunately the factory bearings are often, but not always, marked with a letter code...so double check the clearances with plasti gage.

fit a new high volume high pressure oil pump...only issue is that the clearances in a stock pan 6&7/8 inch deep, 7 inch with pan gasket, are so damn tight that the bottom of the pump body may interfere with the bottom of the pan, so choose your pump carefully...or..

fit a Canton road race (or similar) pan and use their recommended oil pump and dedicated pickup;

I did all the above and things got better, but were never satisfactory...I believe the real issue involves the cam bearings (where the oil goes first), once these clearances loosen up, nothing is really going to solve the problem .

a final band aid might be to fit an oil cooler, either aftermarket or stock l98 style.

good luck

barringt

Thank you very much for the input. Sounds like you did everything but rebuild the engine. If I keep the car I guess I'll have to rebuild the engine if I want to fix the problem right.

rklessdriver

I really don't think that you have an oil pressure problem. If at operating temp, its got more than 10psi per 1,000 rpm your fine.
Will

mtwoolford

well, I'm doing that right now; lol