2000 xj with about 167000. Today my check gauges light came on. Oil pressure was low at idle....like 0. At acceleration it went up but only to like 30 or so and the check gauges light would go off then back down and light on at stop. Oil level is fine. Stopped for about 15 min then started back up and everything seems normal. Oil pressure is about 13 at idle and just at 40 driving. Drove to work and everything was normal. 1. Could it just be a blocked oil pressure sending unit? Clean or replace? 2. Could this at all be a sign of a oil pump failure? ... Can they fizzle out or do they just break?

 

the sending units are known to fail. the passage to the sending unit is known to get clogged. throw a mechanical gauge on it to verify pressure asap.

 

Installing a mechanical gauge where the oil pressure sending unit currently resides is what any shop would do so that is good advice.

You aren't having to add coolant to the coolant reservoir have you? Are you aware of the 0331 cylinder head issue? If not, there are hundreds of threads on it.

The oil pressure spec for the 4.0 engine is as follows:

*Not less than 13 psi at HOT idle
*Between 37-75 psi over 1600 rpms

Good luck and keep us updated!

 

Like I said when I drove the vehicle home after stopping for a few it acted as if it never happened. I am aware of the 0331 (I have 2 2000s, one has had the head replaced and this one still has the 0331). I monitor it closely and plan to overhaul the cooling system this summer. The oil looks good and my coolant level seems fine.




Ill pick up a mechanical gauge on the way home today and test tomorrow when it hopefully will be a bit warmer and dry. I just put it in where the sender goes and run the engine correct? I would assume if I am getting normal readings on the mechanical gauge that I can assume its the sender and if it acts up again I replace it. BTW I am in VA and we have been under 20 degrees for over a week with many days around 5-7 degrees. Not sure if that would create more sludgy conditions that may block the sender? Sound logical?

 

I am in Michigan has been really cold, below zero for a while at night, my oil gauge is sitting at zero but my 2000 Cherokee is running as normal and oil is full. Should I be concerned? What should I try?

 

I did replace my oil pressure sending unit and sure enough my problem was resolved. I'm getting good consistent readings.