cherokee 4.0 oil pressure issue, please help -
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Unread 08-28-2013, 07:11 PM   #1
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Join Date: Aug 2013
Location: Philadelphia, Pennsylvania
Posts: 18
cherokee 4.0 oil pressure issue, please help

98 cherokee, 4.0, around 130,000 miles

Okay, so i am currently running castrol high mileage 10w30 oil, but it did this before i started using this oil. No change, i just always used this oil in all of my vehicles.

Once the truck has been running for a good while and it is at its full running temperature, the oil pressure drops low at idle. It usually will hang on to the last line before 0, so i'm guestimating that this is 10psi. sometimes it looks like 9, but it could be just the angle im looking at the gauge. It NEVER goes below this point. Although, once i accelerate, it rises again, back up to 40/50, whatever is normal. Also, when it is at this low psi, i can hear like a pup pup pup pup (sorry, i dont know how to describe it better) inside the cabin coming from the engine. My chrysler sebring used to make the same pup pup pup noise.

i am definitely concerned, but everyone is telling me that its SUPER common for jeeps to run this psi at hot idle and that the noise that im hearing is normal as well.

additional info: doesnt burn any oil, doesnt use any coolant, coolant is super clean and green, and oil looks absolutely fine.

Any ideas?

YeOlCherokee is offline   Reply With Quote Quick reply to this message
Unread 08-28-2013, 07:28 PM   #2
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1996 ZJ 
Join Date: Nov 2009
Location: michigan
Posts: 969
I've had this before, a new sending unit fixed it.
96 ZJ Laredo, 4.0, 242, 230K
95 ZJ Limited, 4.0, 242, 140K
98 XJ Sport, 4.0, 231, 140K
All work well
bigbill888 is offline   Reply With Quote Quick reply to this message
Unread 08-28-2013, 08:12 PM   #3
Paradise XJ
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1988 MJ Comanche 
Join Date: Jan 2007
Location: Paradise, CA, Northern California
Posts: 2,397
I only have Renix gauges to look at so correct me if I'm wrong about the later models. My gauge has four lines - 0, line, 40, line, 80. Both my rigs idle (hot idle) run at the first line, between zero and I would a$$ume, the first line is 20psi...or 19 in your case...and runs at 40 to the next line...aka60 psi.

Sounds perfectly normal to me.

As far as the pup, pup, pup noise...I dunno.
1990 XJ Laredo - White & Chrome
1988 MJ Pioneer - Metallic Green and Black
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Unread 08-28-2013, 09:05 PM   #4
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1995 XJ Cherokee 
Join Date: Jun 2012
Location: Monrovia, California
Posts: 747
Put a manual gauge in it and see what it is.
Volunteer, American Society of Military History.
Just got a 1989 YJ too!
M35A2 is offline   Reply With Quote Quick reply to this message

cherokee , engine noise , oil , oil pressure , psi

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