Weird 4.0l oil pressure readings

shelby27604

shelby27604

Well-Known Member
Joined
Jun 6, 2013
Location
Efland NC
I was driving my 250k mile XJ this afternoon on the highway (2,500 rpm) when I noticed my oil pressure swinging between 40psi and 15psi. If I stepped on the clutch and let the engine go to idle it would go right to 35psi at hot idle. The XJ is my wifes daily driver, she says she has never seen it do that, but that doesn't mean much.

I haven't dug into it, other than to verify the oil level is fine, and the oil pressure switch isn't loose or leaking, the issue seemed to stop as quickly as it started, and we drove another 50 miles without a hiccup. Oil is a fresh change with a purolator filter....leaning towards a bad sensor or a weird grounding issue, unless people think I need to pull the pan and dig deeper?
 
With 250k, I would start with changing the sensor. 1, they are bad to get hit when changing the oil filter, so maybe it was hit when the last oil change was done. 2, might just have some trash/carbon lodged in it from 250k of normal driving.
 
Spend $20 for one of the El Cheapo Equis mechanical house brand gauges at your local O'Reily and hook it up.
It'll be money well spent ruling out wear vs electrical.
 
I had issues with my old xj having strange oil pressure readings. Pulled the sensor out, and it had a small piece of trash on the end of it. Cleaned it off, and never another issues.
 
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