What is normal idle and operating oil pressure for a 2000 xj 4.0. I just bought it and put a new cylinder head on it and want to make sure everything is good so I don't run into another major problem.

 

it differs from xj to xj, mine is just under 40 on the gauge

 

mine is: idle 20, normal 50

If you search i am pretty sure I saw factory specs here recently.

 

Idle speed should be around 750 rpm

Oil pressure spec for the 4.0 is as follows:

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

If you just replaced a cracked 0331 head, be sure to change the oil a few times (with a small amount of run time inbetween) to flush out any traces of coolant that remain. It doesn't all come out with one oil change. 3 minimum.

 

If you have a lot of miles on your xj, its a good idea to replace the oil pressure sensor, its cheap easy and they do get filled with sludge and filth over time, My old 89 with 189,000 was reading 10psi at hot idle before, after replacing the sensor, it was reading 25 psi at hot idle.