MixterXJ85

Hi there everyone! I used to own a '00 XJ w/ a 5.5RE Lift w/ 33's but retired her 3 years ago. Now im back in the game with a White '01 XJ Auto 138k I bought last week and im very excited to get back into a XJ!

Anyways, on occasion at idle the oil pressure will drop to around thirty with some vibes and pick right back up to around 40-45 when driving. I heard I might need a new oil pump. Any insight my friends? Thanks!

ken72

Its normal, they all do that. What is your driving pressure? Should be around 50 or 60.

N20jeep

30 is fine at idle

MixterXJ85

Thanks for responding Ken. It is usually between 40-55 or so depending on speed. The previous owner was a young kid and I don't think he kept up with the routine maintenace very well so now im left to clean things up. It needs a full tune up wich I plan on doing once it warms up and all of the snow melts here in the Northeast. It probably needs a good oil change.

MixterXJ85

Also thanks N20 Jeep

MixterXJ85

I feel better knowing it's normal! I can't wait to get this baby cleaned up and running smooth! Thanks for the responses guys!

tjwalker

Below are the factory specs for oil pressure on the Jeep 4.0.

You are fine..........

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

81Z4ME

My 2000 Cherokee (4.0 HO) has 105,000 miles on it. Synthetic oil since about 24,000 miles or so and oil/oil filter changes every 6,000 miles = 22 psi at idle when warmed up.

Considerably higher than the IROC but then again the IROC has 186,000 miles on it.

trans_am7935

mine idles at 40 psi hot and 50-55 above 1800 rpms, is this to high? i always though higher was better, except for horrific highs like 100psi or something...

thundaluvin

my 88 idles at 20 and down the road at about 37-40. pump is probably worn so once it warms up a bit I'll change that.

XJ5150

I have been watching mine...

At hot idle it is 35-40 and while driving between 55-60psi on the factory gauge. 1993 4.0 H.O. 249,XXX miles. 10w-40 oil.

billfrank85

Mine stays consistently at about 43-45...hot idle, sometimes drops to bout 35-38.

EBRG

I just purchased a high mileage XJ, a 98, and I have been concerned about the oil pressure. I wish I had 30 PSI at idle. It has 207,000 miles and the oil pressure at a hot idle will do down to the minimum 13 PSI, maybe even 10-13. Of course I have only had it a couple of days and I will be doing a oil change tomorrow to make sure the correct weight oil and a quality filter is on it.

Also I think the sending unit is bad because it will jump around all over the place at a consistent RPM, but only occasionally. I don't think I will stress about this to much until I hook up a mechanical gauge. I hear people talk about a worn out oil pump but I have never heard about this before? If I determine that I actually do have a oil pressure problem how would I determine if it is engine wear or the oil pump, or both. I realize with this many miles low oil pressure is common but there are many vehicles in my family with over 200,000 miles and they all have great oil pressure, even some similar year mopar products like a 99 durango. I just want to get another 100,000 out of it before I put a new motor in it.

(I bought it from my brother. He bought it with 150,000mi and has always changed oil at 3,000mi. He claims oil pressure has always dropped that low....)

EBRG

How big of a job is it to replace the oil pump? Is it worth doing this instead of waiting to do a full rebuild? Thanks for your opinions.