nunnak

I have a 2001 Jeep cherokee (135K). Recently had an oil change at a auto mechanic shop (one of those chain-stores) and few days later started seeing fluid leak marks in the garage. Did not want to go back to the same shop as I was pretty sure they had a plan for me to rip me off and they would not fix the problem. Anyways, soon after oil pressure started to drop to zero ('check gauges'-lights up) whenever its idled and I take my foot off the gas. I saw that this happens only when the temperature reads 210F and not when the oil is still cool. I was praying for a clog to clear out or a non properly fastened seal, valve somewhere during the oil change. So i got another oil change at a different location and nothing changed.

Oil level seems to be fine. Checked it multiple times.
When I took an hour long drive on the highway, the pressure gauge started to become unstable after may be half hour of driving. It is random but it would swing between 40 (normal) and 10. Other than that it was a little scary I did not encounter any other issue running the Jeep.

Is it a faulty guage or oil pump or the sensor? Am I in a dangerous zone?

I would sincerely appreciate any suggestion and greatful if someone can recommend a good mechanic that I can trust to do the job. I live in High Point, NC.

Rockhead

Hey nunnak. I can't answer for what your jeep is doing but mine had similar symptoms. While it's running and the gauge reads zero take off the valve cover oil fill cap, shine a light in there and look for oil flow. The leaking oil could be drips from parts that got oily during the oil change. Mine had fluctuations like that for about a year and then last weekend the gauge spiked to max. I replaced the oil pressure sending unit and everything is great. Good luck with it.

CEScuzzy

Hello nunnak, also keep an eye on the color of your oil and your antifreeze level. If the oil starts to turn cloudy or your antifreeze starts consistently disappearing, it could indicate a problem with the head/head gasket.

I agree with Rockhead on the oil spots, a lot of shops don't clean up properly after oil changes. Your best bet there is to clean it up really good, then drive for a while and check for leaks again. My '01 gauge also dances, though it never drops under 20lbs.

Best of luck with it.

mr.clean

could be the oil pressure switch. They are around $40-$50 for a new one. If you could borrow a mechanical one to put on it to check what your pressure is first to make sure that is what it is for sure. If your oil pressure is really doing what you say your gauge is saying/doing, I would think your motor should have a ticking noise that you could hear.

xjtrailrider

Change the filter, put a WIX on it. Fram filters and other cheap filters have been problematic on the 4.0. Don't forget to top your oil off as well, you will loose almost a quart when you remove the filter.

The oil sender is known for going bad, its located right above the oil filter.

I use Shell Rotella 10w-30 in all 5 of my 4.0's in the driveway and I will only run the WIX filter. Oriellys has the oil and filter you need. Shell Rotella is high in zinc and phosphorus and our flat tappet 4.0 loves that stuff to stay alive for a long time. Regular automotive oils are low in zinc now due to epa regulations.

My son's MJ was rolled over two years ago and ran upside down for quit a bit of time before he came to and shut it off. An engine running upside down is a death sentence since the engine is "oil starved". We repaired it from the roll over. That truck ran for 15k on less than 20psi oil pressure "off idle"! That is amazing and he wasn't easy on it either. It finally put a rod through the block but it still drove 3/4 of a mile after dropping the rod.

Good luck, I'll bet its something simple as mentioned.

meach

I had the same problem not too long ago and it turned out to be the sending unit