I have researched this subject with out a satisfactory answer. So I figured Id ask a few of you. What is your oil pressure while driving and how low does it go at Idle.My 99xj,122xxx runs a consistant 50psi under load and drops to around 20-30psi @ idle. I have noticed on short trips it stays @ 30 during idle and after long hwy trips( about an hours worth @ 70mph) it will go as low as 20psi. Just curious as to what everybody else is running....Thanks

 

thats normal. at idle, when cold, i run about 35 psi, under load about 55 psi. at operating temp idle sits about 15 psi and 45 to 50 under load.

 

From the FSM for my 00...

Oil Pressure

At Idle Speed 89.6 kPa (13 psi)
At 1600 rpm & Higher 255 to 517 kPa

(37 to 75 psi)

 

nothing wrong with your oil pressure.

of all the 4.0's ive had (12) most average 40-45 psi at hiway speeds and at a hot idle 18-25.

If i remember right the FSM say 13 is the lowest acceptable at hot idle.

 

Didnt think something was wrong. I just wanted a better comparison. Looking up the subject the results are very scattered. Other than myself and wife and of course you on the forum, I dont know anyone else with a cherokee. Just hoping to better educate myself,and maybe have a more concentraded place for the subject. Thanks for the responses!!Nice build by the way Tanner. Hoping to be able to get my lift and start my build in the next month or so!!

 

Mine does the same thing. It starts out cold at 50psi and once warmed up it sits at 30psi. Under load warmed up it runs 50psi. Youre good to go.

 

mine bounces around as well.. 30-50 runnin.. on a hot idle mine drops down to nothin and i get a check gauges light.. might have a prob there.. checked with a friend his cherokee does the same thing.. replaced pump and still same thing!

 

10psi per 1000RPM is always what we use as a minium guideline.

 

My '88 XJ runs at 20psi at idle and 45 psi at speed. The engine has 231000 miles! Your OK.

 

my zj is weird it never goes below 20 but some times maxs out at 80 flutters there and some times stays at 50

 

my 87 runs about 45 to 50 at highway speed 20 at idle when warm,its got 262,000 on it

 

Definitly check it out.maybe sending unit.Hey thanks for all the posts.Made feel better about it!!

 

Mine runs between 40 and 50 at highway speeds then drops to around 10 at idle.