I have recently developed a considerable oil leak. My mechanic has identified the source of the leak as the oil sensing unit. After replacing the unit 3 times I had him check the oil pressure. The oil pressure will spike to over 80 lbs of pressure but will also go down to the normal pressure. The high pressure forces oil through the sensor, not the threads but through the sensor and leaks profusely within a couple of days. He has indicated that there is a pressure check valve in the oil pump which is probably sticking. Does the oil pump need to be replaced? Can the sensor be removed and plugged? What issues might I be facing on this?
The car is a 97 Lincoln Mark 8 with about 220,000 miles but has been a sound car.
Plugging the oil sender hole isn’t the solution. The high pressure will still be present and it’ll just find the next weakest point to exit- likely a more expensive route like a crankshaft seal or something.
If it is the oil pressure bypass that is sticking, it’s probably indicative of a more systemic problem- sludging. With 220k miles, it wouldn’t be hard to believe that you have some sludge buildup. I might be inclined to try to run some engine cleaner through the motor. Lather, rinse, repeat a few times to see if you can clean it up a bit in the least intrusive manner possible. Sometimes, once you remove the sludge, you find it was also blocking other leaks around dried up seals that now leak too.
Sounds like you need to fix the pressure check valve, the overpressure may cause other problems with seals. Since the pan probably has to be dropped, it may be better just to replace the pump+valve.
Are you using the correct weight oil?