The most common problem is a bad oil pressure switch on the 99-02 grand cherokee with the 4.7l v8. The part has failed on 90% of all 99-02 grand cherokees I have worked on. The housing is junk,but since it has lasted longer then 36,000 miles the factory would not issue a recall. The oil pressure switch can be purchased at any outlet. but have found the duralast was decent. that being said Go to autozone and get part # PS471 (oil pressure switch for 1999-2002 N code 4.7L V8.) chances are if you encounter the same problem after replacement you will need to drop the oil pan and un clog the oil sump.
To replace the switch, under the hood look for the power steering pump on the driver side of the vehicle, to the right and under the p/s pump is the oil pressure switch, If it is wet, its bad for sure, remember to disconnect the battery before service,as not to harm the gauges.
SOURCE: My 02 Jeep runs great but oil pressure reads High all the time
oil pressure sending unit is not working right.
SOURCE: Oil pressure gauge
Low oil pressure is generally caused by internal engine bearing wear, not a "bad" oil pump... Pumps become "bad" when debris from a failed component gets into it, causing damage. (exception being pressure regulator spring/plunger assembly becoming clogged with gunk in engines that do not get proper maintenance; likely not your case)
Were there any tapping noises coming from engine when pressure was low? If not, The most common problem is the pressure sending unit, sending bad info to the warning light. If passage going to it or internal passage is gunked up, this problem usually disappears when oil is changed. sometimes the sender just goes bad, in which case, change it.
To get a proper diagnosis on your problem, have someone put a mechanical oil pressure gauge on it. This will read the actual oil pressure and will tell you a lot about the condition of your engine!
I have never seen a valve job that corrected any oil pressure problem. I mistrust anyone who would even think that!!!
Mlinimum low pressure at idle is 15 psi Max is about 60psi running (higher can explode an oil filter) A reading of 15psi indicates the beginning of a problem. although considered "safe" it is not good.
SOURCE: Oil pressure gauge drops after running and sitting still
The Oil pressure sensor seams to have gone bad and needs to be replaced soon as possible as they tend to leak oil soon after. There common to go bad and start with that since it's easier then replacing the oil pump, but if you don't hear any ticking from the engine and you have good pressure when the engine is cold then it's the sensor.
The 4 cylinder oil pressure switch is located below the A/C compressor. It is a single wire connection with a gray/yellow striped wire.
The 6 cylinder oil pressure switch is located on the passenger side rear of the block. It is a single wire connection with a gray/yellow striped wire.
Good luck and hope this helps.
SOURCE: 2006 Yukon Denali, oil pressure gauge malfunction
Most likely the oil pressure sensor is bad. Its located in the very rear of engine on top of bell housing area.
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My Oil Pressure goes down to almost zero sometimes when going downhill. I've changed out the sending unit but still it persists. The engines still runs just fine during this, but it is shaking my confidence in the car. Anyone else had this problem?
I have actually run into the same problem. My oil pressure is at zero, but no other symptoms are occurring.
I think it could be the oil pressure sensor.
truck runs great, came to a red light,dropped to zero and check gauge light came on. checked oil fine. checked filter wet. checked oil pressure switch.bad. apparantley this isnt an unfamiliar problem, I went to jeep to buy a new switch and was informed they go all the time on the 99-02 grand cherokee v8
check gauge kight lit
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