If an oil-pressure gauge tests good but doesn’t move with the engine running, there are two ways to determine if it’s an oil-pressure problem or a bad sending unit. The best, and cleanest, way to test oil pressure is to remove the oil-pressure sending unit and use a mechanical pressure tester. If you don’t have access to one, pull the sending unit and have an assistant turn over the motor with the coil wire disconnected or briefly run the engine. If oil shoots out, the pressure is probably okay and the sending unit is bad. If it just oozes out, you have a serious problem. You can bypass this step and put in a new sending unit, but if it doesn’t fix the problem, get out the paper towels.

Click to expand...