I have a 94 With a 4.3L. 8 months age I did all new bearings new seals oil pump. last month the lower oil cooler line was leaking at the radiator. The next time I drove it the oil pressure dropped when it came up to temp. This is a overnight issue, one day fine the next it went to crap. When the light oil light comes on the car shuts down. At that point there is no knock or anything. Could the bypass on the cooler be opening? the motor is completely clean and runs great. Please help.

 

Could be a faulty oil sensor. From what i remember if oil sensor senses no pressure it cuts power to the pump. Hook up a mechanical oil gauge to a T fitting with the stock one. see what it says when you have the issues.

 

sorry I forgot to say I did put a mechanical guage on it and it showed the say low pressure