2000 Jeep Cherokee low oil pressure while driving

MOSEBY8

MEMBER
2000 JEEP CHEROKEE

Engine Mechanical problem
2000 Jeep Cherokee V8 Four Wheel Drive 77400 miles

I was getting "low oil pressure" when letting off the gas but it showed normal while driving. I found the oil pressure sensor connection full of oil and replaced the sensor. Now I have the opposite condition. Pressure comes right up to 40# + at idle (hot or cold) but then guage drops to zero while driving. A soon as I let up on the gas, the gauge comes back up to 40#. I thought maybe I had a defective new sensor so I returned it and replaced it with a better one (Echlin). Engine seems to run excellent with no noises. Any ideas? I'm stumped.

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

First, if you don't hear any ticking or knocking noises when the engine is running, chances are the engine is fine (I think you already know that). What you described really makes no sense other than if there is a damaged wire or bad connection to the gauge. If may not be able to handle the added power going to the gauge. Also, make sure the terminals are making a good connection. You mentioned the plug was oil filled.

With the engine rinning, slightly rev the engine until the gauge reads 0. Move the wiring around while a helper watches the gauge to see if there is a possible short or bad connection. Check wiring for continunity or resistance to determine if there is a bad one. If all is good, I would move to the gauge itself.

LEt me know what you find.

Joe

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Friday, January 15th, 2010 AT 2:57 PM

MOSEBY8

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7 POSTS

Thanks for the advice. Your thoughts seem to make good sense. I have moved the wires to the pressure sensor around a bit, but this proves to be a bit difficult while the belts are running. Regardless, I have yet to see any difference. In the meantime, I took some advice from others and flushed out the oil sensor port and also replaced the oil filter. To no avail. I also checked my pressure with a manual gauge, which showed very good.

Recently I have noticed that if I drive the vehicle a bit and stop it momentarily (i.E, to run into a store) and then restart it while it's still warm, the oil pressure gauge starts working normally. I'm guessing that the heat of the engine (with the radiator fan NOT running?) Is causing the problem to correct itself somehow.

Any guesses?

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Friday, January 22nd, 2010 AT 9:16 AM

MOSEBY8

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7 POSTS

After checking many possible causes, and replacing the sensor twice with NAPA products, I finally took the Grand Cherokee to a reputable repair shop. They did a diagnostic and could find no problems either and then consulted a national database where they saw that this is a common problem with Jeeps. They need to have a GENUINE CHRYSLER/JEEP sensor installed. They did that and that took care of the problem. It works great now.

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Tuesday, February 9th, 2010 AT 9:17 AM