Kehoe

Hi all,

I did some searching, but most of what I could find regard the oil pressure guage pegged at 80 psi as a sign of a bad OPSU. Hopefully this isn't a repost.

I have a 2001 XJ which I've owned for a little over a year. Since owning it, the oil pressure gauge has always read between ~15psi and 20psi at a hot idle (e.g., after a 30 minute highway drive).

Starting this week, the gauge is reading about 30 psi during a hot idle. I know this is within spec, and typically higher pressure is better than lower pressure, but is this jump in pressure anything I should be worried about? Or, is there anything I should be checking? If it matters, I'm about due for an oil change as the last change was approx 3000 miles ago.

Oil pressure under load appears to be pretty similar as it has always been (maxing out at about 60 under load when cold, settling around 40-50 under load when hot).

Thanks

cruiser54

I wouldn't worry about it.

Had a recent oil change?

What brand of oil filter do you have?

Kehoe

Same as I always do - motorcraft. Thanks for the quick reply

jpz

I recently replaced my sending unit due to similar issues as you are having. My oil pressure was displaying higher than normal. New sending unit, problem went away.

tjwalker

A new MOPAR oil pressure sending unit will likely resolve it.

I like MOPAR sending units for the best accuracy and reliability and compatibility with your factory gauge.

Ozalid

I had my oil changed yesterday...I'm going down to Baja next month so I had them put in 10/50 synthetic...And Up here in Washington the weather is pretty moderate.
My idle oil pressure went from 20 psi to almost 40psi...And its running about 15 degrees cooler than before oil change..
AND , Ive been on the trail of an oil leak..mechanic said probably rear main seal... But posts here have recommended looking up and elsewhere for the leak...
After a 45 minute drive home, i crawled under the Jeep with my work light..... the leak has either stopped or slowed to almost nothing....?
Ill be keeping an eye on it and my fingers crossed..

Tbone289

You kind of have to wonder... If the oil is too thick to flow through a leak, how well is it flowing through areas of the engine with tight tolerances? Your increased pressure indicates that it isn't flowing as well as the viscosity you were using before.

Ozalid

If I lived in a colder climate, I might not have put in 10/50....Before oil change idle pressure was at 20psi..I believe that is about 10lbs below spec..
and remember, my engine is now running 15 degrees cooler....Im not convinced the oil was the only factor in the leak stop/slow down... It might have been a leak at the oil filter or drain plug ?
Thanks for your feed back....

Tbone289

Hard to tell where the leak was, but that is possible. According to FSMs, oil pressure spec for the 4.0 is 13 psi or greater at hot idle. 20psi is perfectly normal.

Ozalid

Hmmm Not sure where I read 30 psi at idle..?
Anyhow, I've been doing some reading on oils...Man there are many different opinions. But you are correct about thicker oil maybe not getting to tighter tolerance areas..
I was a bit concerned, but reading more about 100% synthetics , they are thinner and flow better than regular oils...SO , I hope I haven't over done it...Ill keep an eye on my gauges.
But this Jeep will be living in Southern Baja after I drive it down...Another Jeeper in Baja recommended the 15-50 synth. Says thats all he uses... He's a retired career auto mechanic..
Later

Tbone289

I'm not trying to say that it's going to do any great damage... It just may not be the best choice.

Kehoe

To close the loop here for archival purposes: I changed my oil, oil filter, and replaced the oil pressure sender, and now things are back to normal. Thanks all for the help and discussion.