Hey everyone, this is my first post here, so please forgive any mistakes I make . I recently bought a 2002 Jeep Grand Cherokee with the inline 4.0 6 cylinder engine. It runs and drives great, but after it heats up the oil pressure drops to almost zero! The engine sounds fine, no knocking or clicking. I've replaced the sending unit and the oil pump. The oil pump was replaced with a high volume oil pump (to correct the issue, yeah it didn't work), not sure if that means anything...

It just puzzles me that an engine can run on such low oil pressure without knocking. I love the rig, but do not understand why the pressure drops to the point where the "check gauges" light comes on, yet the engine sounds fine!

Any input is appreciated and thanks in advance!

 

Welcome to the club. Mine has had the same symptoms for so long I don't pay any attention to it. In fact I am taking a trip across the state tomorrow and I am not the least bit concerned.

 

Thanks for the response! The rig runs fine, but in all my years of automotive experience I have never seen anything like this. I'm just puzzled.... Every thing seems ok beside the gauge...

 

There's another thread on the same issue not too far down from yours you might find interesting:
https://www.cherokeeforum.com/f2/oil...4-0-i6-172694/
It seems to be more common with the 99+ for some reason. Quite a few members appear to be running single-digit idle oil pressures with no harm done.
Ever put a mechanical gauge on to see what you actually have?