Sight Gauge

why does my oil pressure gauge keep going up and down in pressuer?

my oil gauge on my jeep cherokee keeps going up in down in pressure, why?

Public Comments

1. This could be caused by any number of problems. The first thing I would do is to consider replacing the oil pressure sending unit. Most times this is simply a bad sending unit. It could be caused by sludge build up. Worst case the oil pump pickup screen could be partially blocked with crud. Mostly caused from neglect. It could be caused from wear. When an engine is worn the lifter bores can become enlarged. Oil can bypass the oil passages and the engine loses oil pressure. If the lifter bores are worn they can not be repaired. When engine bearings wear they leak too much oil and the engine can lose oil pressure. This can be repaired. Bearings can be replaced. The crankshaft can be turned and the correct bearings can be installed.
2. How low and how high? What engine do you have? Check the specs for your engine to see if it is in the normal range.
3. It is due to worn rotors on the oil pump.
4. Typically the OP will be high when the engine is cold. Then as the engine and oil warm up the OP will drop. When the engine is hot the OP will fluctuate with the engines RPMs.
5. Mad Jack gave you the best advice. What you should take notice of is the actual performance of the engine. If you can't detect fluctuations in the idle or revs, its most likely the sending unit. This is a simple replacement, so don't let a mechanic or dealer tell you its a complicated repair. If its only the sending unit, its entirely up to you if you replace it.
6. You didn't mention year or anything, so I can't check if they shared parts, but the early TJ's had notorious problems with bad oil pressure sending units. The needle was all over the yard, down to zero, up to full etc. Look into whether the Cherokees shared this problem. You can have somebody put an external gauge on it to verify that the pressure is indeed going up and down. If it shows steady on the external gauge than replace the sending unit. Its 2 screws and a 50 dollar part from Pep Boys.