I have a 2000 Cherokee Sport 4.0L w/ 189k miles and recently (past couple weeks) the oil pressure gauge has been maxing out at 80psi. When the engine is cold it is constantly maxed out but once it warms up the pressure drops to ~50psi when stopped and idling then shoots back to 80 as soon as you start giving it gas. I just changed the oil and filter last weekend and it has the correct oil level. I was thinking it could possibly be a defective gauge but I'm not sure if that could be the case seeing as the pressure drops to a semi-normal range once it's warmed up and idling?

Any ideas would be greatly appreciated!

 

Its not going to hurt anything but try changing your oil pressure sending unit

 

99.999% It's the oil pressure sender. They fail by reading extremely high...or dropping to zero at idle, and failures are pretty common. It's located on the oil filter adapter housing....get one from Jeep and replace.

The fact that it drops down a bit once the engine warms is typical...a good sender will show the same.

 

Thanks! I'll replace the sender this weekend and see if that fixes the problem.