low to no oil pressure after rebuild
rebuilt. bearings /rods/ new oil pump/sensor/lifters/ every thing . starting oil pressure 60psi. after 30 min. warm up low to no pressure. been back thru 3 times . same thing .. im missing something ..
2001 3.8 chevy/ buick k vin sorry
Bearing clearance might be out of spec, possible clog, oil not heavy enough, or there could be an internal oil leak early in the oil system that's temperature sensitive.
i installed cam bearing as you would a norm motor im thinking from reading others. hole is to big. some redrill smaller..oil is 5 w 30 bearings plastigauge good. oil relieve valve is good not sticking. new pump and gasket.
didnt bore block all was good no ridge. old bearings looked good for 100k
As you probably know, oil pressure is a result of a resistance to oil pump output. The resistance comes from the main journals and the connecting rod bearings. Something has to be going on with them. Nothing else is changing enough when the engine warms up.
If you are doing another tear down, change the oil pump, and make sure it is one for your engine model. Make sure the bearings are not in backwards or upside down. Sound silly, but it has happened. I lost a 51 MGTD motor because of an incorrect spring rate in the outside oil pump. This is not your problem, but something simple that is overlooked or a wrong part is replaced can cause the issues. As others said, check cylinder pressure, check the bearing size, correctness and placement. To fix it, you may need a complete tear down and I'd rebuild with new bearing all around and oil pump. Air in the system or bearing failure that does not maintain pressure. Also check the sending unit, the line to the pressure gauge, and the gauge itself. I'd get an external reading on the pressure using test equipment before the tear down though and make sure it is not your send/sensing units. Good luck and have fun.
think its to much bearing clearance..the oil relief valve just lets oil flow thru filter and you can block it if you want all the oil to run thru the filter first but that wouldt explain it.. the engine gets hot and clearances expand ..pressure drops....im sure you set up the pickup... good luck
I have the same problem. Going to drain my oil and look for Babbitt, thought I had it right.
