Alright, I searched the forums and could not find what I need. 2000 grand Cherokee with a 4.7, 156000 miles, runs good, haven't noticed coolant loss. The oil pressure gauge spends it's time on 0 psi. It will raise while idling and not while accelerating. Any thoughts?

 

Hook up a mechanical gauge and verify it.

 

Other than sticking a manual guage on it to verify actual pressure. Guage senders have been known to fail, also when/if you remove the guage sender, stick a pic or small screwdriver into the hole and see if its plugged with sludge. You can even start the engine up for a second or two to blow the hole out with oil pressure, keep in mind it will spray oil out so dont let it run more than a couple seconds.

 

Do you realize how much oil will spray out in just a few seconds? I don't recomend doing that. Change the sending unit. They are cheap enough.
If you have no oil pressure, you should be hearing some bearing rattle with 160K on it.

 

Of course it can make a mess, I was offering that as a solution to possibly blow out a sludge pocket that can develop behind the sender in the oil passage which has been known to happen. A couple rags placed at the hole and drain pan under the area would probably be all that was needed to prevent a mess.