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Low oil pressure (16 psi) at warm idle

eightsevenzero

NAXJA Forum User
Location
San Antonio, TX
I've had quite a few XJ's but the 97 I just picked up (147k) is the only one I've had that shows 16 PSI at warm idle. At 1600 rpm it jumps right up to 40-45 PSI and operates solidly at 40-45 PSI at anything but idle. Just changed oil (Mobil 1 synthetic 10w-30) and filter just to be sure it wasn't a faulty filter. I know I should do a mechanical gauge check just to be sure but assuming it's right is 16 at idle is cause for concern? Apart from a steady miss at idle (I posted another thread about this) it runs great.
 
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I've never had the issue of low oil pressure at idle without engine damage. I've got main bearings that got eaten alive during break in and I hold 3-7 hot at all rpm and 40 dead cold. It progresses down.


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I've never had the issue of low oil pressure at idle without engine damage. I've got main bearings that got eaten alive during break in and I hold 3-7 hot at all rpm and 40 dead cold. It progresses down.


Sent from my iPhone using Tapatalk
Same here. I've run 3psi hot idle for over 100k miles :eek:

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10 is the factory spec.
 
Gotcha. Curious, what would cause my last XJ, a '99 with 187k to have higher oil pressure at idle than this one with 147K?

The oil gauge is mostly an indicator, not a calibrated measuring device. The pressure sensor may be off slightly, or the motor simply has better or worse oil pressure than the next 4.0L. Some Jeeps have a bit higher oil pressure, and some a bit lower, neither will explode anytime soon.

Lots of people have driven lots of miles with less than perfect oil pressure.
 
My 2001 has 10 at idle, 50 at 50mph. Gradually drops to 40 at 50 mph. Thats where it stays until I change the oil/filter, it then goes back to 50 at 50. Been that way since the start.
 
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