Sport cherokee said:
Xj 99 4.0. When I start it up after being parked the oil pressure will rise to around 40 at the highest when idling. When I drive Pressure is fine, But when I stop at a red light or to park Check guages light come on and I notice my oil pressure is at( 0 ). This happens every time like clock work.
When i'm driving oil pressure is fine. When I idle at a stop it drops to (0).
What is this from and how serious is it ?
Change the CLOCK, LOL:roll:
All joking aside, Several of us have experienced similar problems including me. I doupt it is the sending unit in your case.
How long has it been since you changed the oil and filter?
What brand and viscosity oil and filter do you have?
How many miles on the engine?
(1) I would not drive it the way it is. Way too risky.
(2) First get a new oil filter (use a good quality one like Mobil one or K & N, anything but Fram) , change the oil filter.
Test the hot oil, idle oil pressure with the new filter.
Then add a quart of Lucas 100% petroleum based Oil Additive.
Restart the engine and retest the oil pressure. Then test drive it to see if the hot idle pressure has come up any.
The minimum hot idle oil pressure is 13 psi for Jeep 4.0's.
If the hot oil, idle, oil pressure comes up, my next suggestion will likely be to change the oil to 20W-50 oil with a quart of Lucas oil additive.
Let us know the results of your filter and oil test.
To read a recent, thourough discussion of your problem follow the link below:
http://www.naxja.org/forum/showthread.php?t=901210