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Oil Pressure

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Old 07-29-2009, 04:27 PM
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Default Oil Pressure

Just noticed that my oil pressure gauge is reading 10 at idle. Never noticed this before. It will go up to 40 while under load. There are zero leaks anywhere and the oil level is perfect. I've only had it for a few weeks now, and I honeslty though it was always around 40. My guess is that either the sensor is going out...or I will have to change the pump. Any ideas?
Old 07-29-2009, 04:48 PM
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Mine runs around 40-50 while driving and 10-20 when idling,I have the stock guage and a mechanical one,I would like it to be higher than 10,but I am not concerned about it,I just looked at the haynes and it says 13 at idle and 37 to 75 above 1600 rpm. I guess 10 ok.
Old 07-29-2009, 06:13 PM
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check it with a mechanical gauge they are much more accurate it could very well be you r gauge in the truck is bad the sending units go bad after a while and even when working good they arent all that accurate
Old 07-29-2009, 06:43 PM
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mine usually reads 20 psi at idle and 60 psi at load.
Old 07-30-2009, 12:16 AM
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Originally Posted by mixed89
Mine runs around 40-50 while driving and 10-20 when idling,I have the stock guage and a mechanical one,I would like it to be higher than 10,but I am not concerned about it,I just looked at the haynes and it says 13 at idle and 37 to 75 above 1600 rpm. I guess 10 ok.
yeah thats what mine does 10 at idle and 35+ while acclerating or such
Old 07-30-2009, 05:19 AM
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Originally Posted by jd4x426
check it with a mechanical gauge they are much more accurate it could very well be you r gauge in the truck is bad the sending units go bad after a while and even when working good they arent all that accurate
Yeah, that's what I was thinkin, a mech gauge, just need to find a fitting that matches the thread of the sender. I think it may have been stuck before, because I'm pretty sure it was always at 40. It may have become unstuck and now it's reading correctly since the book does say 13psi at idle.

It would be nice to get a consensus on what most XJs read at idle. I would hate to loose an engine due to a cheap oil pump.
Old 07-30-2009, 11:36 AM
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You need 10 PSI of oil pressure for every 1000 RPM.

Sounds like yours is normal.
Old 07-30-2009, 11:44 AM
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hmmmm should i be concerned if mine usually stays right around 60? it goes right there when i start er up and stays there pretty much the whole time.
Old 07-30-2009, 11:59 AM
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Originally Posted by strikechords
hmmmm should i be concerned if mine usually stays right around 60? it goes right there when i start er up and stays there pretty much the whole time.
I would not trust it,mine did that to me and it was just the wire at the sensor. I would look at it,sounds like you are flying blind.
Old 07-30-2009, 12:00 PM
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Originally Posted by strikechords
hmmmm should i be concerned if mine usually stays right around 60? it goes right there when i start er up and stays there pretty much the whole time.
That's how mine was except at 40...when it dropped to 10 at idle I freaked out. It sounds like now it's working normal so there was probably some junk in the elbow or the actual switch that cleared out. I ordered a new switch anyhow. Ordered it from quadratech 24 bucks shipped.
Old 07-30-2009, 01:28 PM
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Originally Posted by strikechords
hmmmm should i be concerned if mine usually stays right around 60? it goes right there when i start er up and stays there pretty much the whole time.
If it doesn't vary with engine temperature or RPMs it is probably giving a false reading. Something may be wrong with it.


"Yeah, it read 60 PSI right up to the point of my engine seizing up."

Old 07-30-2009, 01:53 PM
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Originally Posted by Firestorm500
If it doesn't vary with engine temperature or RPMs it is probably giving a false reading. Something may be wrong with it.


"Yeah, it read 60 PSI right up to the point of my engine seizing up."

Oh, damn...
Old 07-30-2009, 01:58 PM
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10psi is acceptable. I have an 88 that I thought there was a problem with so I changed the switch. Everyone insisted that "I've never replaced a jeep oil pump." I did an oil pan gasket and that was HELL! So I changed the pump while I was in there.

With the before pump I would idle at 10psi and with the new pump it would idle at 20psi. It just comes with age, wear, and tear. When it dips below 10psi when turning is when you know you need to add 3.5 quarts of oil. I know that is awful but I couldn't get the bolt on the oil filter adapter loose to change the seal(s).
Old 07-30-2009, 02:52 PM
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Mine is 40psi idle and moves up to 60psi under load. So I take it Im good, even with 175,000 miles. That makes me feel better. Time for a turbo, jk!
Old 07-30-2009, 04:11 PM
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Originally Posted by 2.5TURBO
I did an oil pan gasket and that was HELL! So I changed the pump while I was in there.
my friend has an 88 wrangler, his oil pan and gasket were leaking, idk if its stock or someone put it on there but there was a skid plate welded onto the oil pan, so we took it off, found were it was leaking, brazed it, and put a new gasket on. it sucked, he got oil in his eye haha, i was wearing safety glasses tho. guess it doesnt have anything to do with the pump, or a cherokee, but its a jeep!


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