what part brings oil pressure back to standard??

[erickmarciano]

is it  used main bearings or used oil pump that cause low oil pressure?
should the oil pump always be replaced in a rebuilt?
Thanks

Ps: will have so many questions soon.
Thanks
all

[al_lieffring]

The oil pump can be replaced fairly easily with the motor still in the car by removing the lower oil pan. If changing the pump helps, problem solved, if not the pump should be replaced with an engine build anyway.
Another thing to check it the oil pressure releif valve located behind a 24mm hex plug on the front of the block next to the distributor drive housing. do a search and I think you can find a picture of it's location.

[ja17]

Hello Eric,

Catastrophic engine failure will cause a lot of metal to circulate in the oil ruining the oil pump, main bearings and rod bearings. In this case the oil pump is always replace. Normally it will last the life of the engine, but as Al suggests it should be replaced during a major rebuild.
Worn main and rod bearigs cause excessive loss of oil as clearances grow beyound specs. Low oil pressure results. Worn cam bearings will cause some oil pressure loss also.
During a rebuild "Plasti-gauge" is used to check the clearances between the beaings and crankshaft. Too tight or too loose clearances can destroy a freshly rebuilt engine.