Oil pressure gauge barely moves away from 40psi - JeepForum.com
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post #1 of 7 Old 02-02-2013, 03:45 PM Thread Starter
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1997 ZJ 
Join Date: Aug 2012
Location: Nashville
Posts: 194
Oil pressure gauge barely moves away from 40psi

This is a short and simple question that I can't seem to find an answer to anywhere on this forum or Google. No matter what the temp is (ambiant or internal engine), what the RPMs are, what the engine load is, the oil PSI never moves farther than about 35 to 45psi and generally just sits a hair under 40psi no matter what once everything is warm. When I first entered the Jeep world by buying this Jeep (which I love to death ) I always thought it was normal till I got a Haynes manual and flipping through it I noticed it said 13psi idle and then 37 to 75psi above 1600rpms. And a friend of mine that owns a Grand Cherokee (whatever the next generation is) with an inline six his oil gauge moves from 20 to 70 depending on RPMs so I was wondering is this normal or does the sensor need to be replaced? The engine is silent other than on 20F and colder days it will click/clack very quietly (have to stand right next to the hood to hear it) for the first few minutes in the morning of idling with 10W30.

herculeesjr is offline  
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post #2 of 7 Old 02-02-2013, 04:07 PM
Web Wheeler
1998 ZJ 
Join Date: Aug 2010
Location: Virginia
Posts: 5,548
Your engine is healthy.. Both my 5.9 and the 4.0 sit at 43-40psi when cold. and after beign driven for 10 minutes or so they idle at 30 PSI idle and when driven they are at around 35-40psi when driving normally in the city. The manual saying 13 is bare mininum but i wouldnt want an engine if it were at 13.. and your friends going from 20-70 i dont think id like either.

Good oil pressure is oil pressure that doesnt fluctuate going back and forth by large amounts like your friends does.. Or Oil pressure that is extremely low a worn out engine is an engine that sits at say 10psi and goes up to 40 when reved.
Candymancan is offline  
post #3 of 7 Old 02-02-2013, 04:07 PM
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1998 ZJ 
Join Date: Sep 2010
Location: Lake Forest
Posts: 868
You're fine. The fact that is doesn't drop way down at idle means that your pump is good and your bearing clearances aren't badly worn.

My 5.2 runs 30-50 depending on RPM & if it's warmed up or not. Cruising at 65 when it's warm, it's right on 40.

I use 5W-30 so it's not oil starved on a cold start for quite as long. When it heats up it's the same as 10W-30.
kachink is offline  
post #4 of 7 Old 02-02-2013, 04:13 PM Thread Starter
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1997 ZJ 
Join Date: Aug 2012
Location: Nashville
Posts: 194
That's the main thing I was wondering is if the engine really is just staying at 40psi or if the sensor was bad and somehow stuck at 40psi. I just was expecting the pressure gauge to fluctuate more than a few psi. Thank you for the info!
herculeesjr is offline  
post #5 of 7 Old 02-02-2013, 04:16 PM
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1998 ZJ 
Join Date: Jun 2009
Location: LHC, AZ
Posts: 515
Your golden dude. My oil pressure sits at 30 all day everyday.
98GCLimited is offline  
post #6 of 7 Old 02-03-2013, 12:24 AM
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2007 JK Wrangler 
Join Date: Oct 2008
Location: Calgary
Posts: 2,571
its good.

don't listen to those 4L guys; different motor, different beast altogether!

07' JKUR rollin on 35s
JohnnyZJ is offline  
post #7 of 7 Old 02-03-2013, 10:08 AM
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1998 ZJ 
Join Date: May 2012
Location: Columbus
Posts: 211
Makes me feel good. 40 all day every day.
NewtoZJ is offline  

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