Just bought 54 chevy 3/4 ton with 235 engine, oil pressure starts off at 30 psi when first started. Had to drive it to the tag office, the pressure droped to near zero, however no engine knocking or unusal noises. Have changed the oil and added a new oil pressure gauge same results. I'm thinking if the pump was bad I'd have shelled out the motor by now. I have an add on filter,I believe the oil pressure gauge hookup is on the out going side from the filter, do you think something is plugged in the filter line or is it the pump. Hate to drop the pan this old truck has zero oil leaks. Thanks for any advice
