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High Oil Pressure 2000 Cherokee ??

oldbill

NAXJA Forum User
Location
Michigan
My wife's vehicle, I don't drive it that often, but noticed this winter when first driven that that the oil pressure was at 80psi on the guage. Thought it might have been the oil weight 10w-30, changed the oil this time using 5w-30 synthetic blend. Oil presure when driving still hits around 80psi, until driven a few miles, usually over 20 miles, then seems to come down some. Oil pressure does rise and fall with rpms. Oil pressure has alwats been in the 60 psi range or above. Wife is concerned with it being at 80psi. Have not put a manual guage on it it. Anyone else experience anything like this with their unit. Should I have any major concerns? Engine has about 150000 miles on it and runs strong. If it is the pressure releif assemblt, how much of a pain is it to change and what would your recommendations be.

Thanks in advance,
Bill
 
Oil pressure sending units and their wiring are a common problem with the 4.0L Cherokee. A mechanical oil pressure gauge will probably show normal oil pressure, 10-20 psi at warm idle and 40-60 psi at 55 mph.


Scroll down to the very bottom of this page for some similar threads.
 
I agree with Tim; this is most likely an oil pressure sending unit problem. You can verify it with a "mechanical" oil pressure gauge if you like but a lot of guys just swap them out because they are a common failure. When they fail, they usually fail on the high side. I purchase this part directly from Jeep for best reliability/accuracy/mating with your factory gauge.
 
I'm on board for testing with a mechanical gauge--nothing like a little peace of mind.

Also agree, most likely a sending unit problem, buy a quality NAPA or dealer sender after you test the pressure.
 
Thought I had found the problem yesterday. Turned the ignition switch to run without starting the car, all guages read good, except? oil pressure. Gauge indicated about 30psi without the engine running. Took a trip today to take the wife for her treatment, stopped at Harbor Freight, picked up a oil pressure tester and fuel line pressure tester, then headed to Frankenmuth for a chicken dinner, early birthday dinner for the wife. On the way home the oil pressure gauge starts working in the normal range again, about 60psi doing 60mph or so. Told wife, I'm going to hold off on replacing the sender for awhile. We joke that when something like this happens it's my Dad who has been dead for awhile, he was always a joker.
 
It is going to be the sending unit. Change it out!
 
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