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Unread 07-01-2013, 09:55 AM   #1
AdamZJL
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1998 XJ Cherokee 
 
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Loss of oil pressure at idle

I've got a 1998 Cherokee Sport with the 4.0L, about 380,000km, i was on my way back from a camping trip this weekend when i noticed every time i was slowing to stop at a light or stop sign, or even slowing down for a turn, my oil pressure would drop to 0, i would have to brake with my left foot and hold the revs up in neutral to keep it up in the safe zone.
As long as it was either under throttle or coasting above about 20km/h it was fine, but would drop when going any slower or stopped, i believe it to be the oil pump going on the fritz but am not 100%, anybody know what it may be or have had the same issue?

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Unread 07-01-2013, 10:19 AM   #2
CitadelXJ
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My suggestion would be to get some kind of manual gauge for it to double check your pressure. Your oil pump might be okay and the gauge might be screwed up. I would do that before the hassle of dropping the pan and changing the oil pump.
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Unread 07-01-2013, 10:46 AM   #3
skyway0018746
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It could be 1 of 2 things, with that many miles the oil pump could be on its way out or your main bearings could be worn. Is oil pressure higher when the engine is cold?
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Unread 07-02-2013, 09:39 AM   #4
AdamZJL
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It doesn't seem to be any different when cold, i'll probably go out today and start it up, see if it's still doing it, i need to drop the oil pan at some point anyway due it's rusted through and leaking.
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Unread 07-02-2013, 10:35 AM   #5
skyway0018746
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It may be the pump then , if your going to drop the pan then its a no brainier to change the pump
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Unread 07-02-2013, 01:05 PM   #6
BigBadDad
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I had low oil pressure on the Wife's GC with the 4.0. I was convinced the oil pump was worn out, so I replaced it. Did not solve the problem! I found that the oil pressure sending unit was bad. That did solve the problem. Boy, did I feel stoopid!
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Unread 07-05-2013, 11:12 AM   #7
AdamZJL
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I've been doing a lot of research on this and i'm really not liking some of the things i'm reading, but i'm really liking some of the things i'm reading. I have found things from something as simple as the oil filter, to the sending unit, to the bearings, to the head... knowing my luck it's probably... all of them lol.

Due to the research i did i have some more details i may be able to add, try to get this as detailed as possible so i don't have to keep playing the guessing game, or at least narrow it down.
I see a lot of people talking about psi, i don't know what the psi is on mine, it doesn't say (i'm in Canada), i just know that it shows a 3 in the middle and obviously a 0 at the bottom, it holds around 3 or higher when it's under throttle, but when i come to a stop, or when i'm almost to a stop, it's oil pressure drops quite quickly down to 0 then the check gauges light comes on, i can keep it in neutral or park at a stop and hold the revs up and it's fine, but when i try to take off if the revs drop too much allowing the oil pressure to drop it will bog and sputter, and on one occasion it actually went as far as to stall... when it first started it was fine, but after about 15-30 seconds it would drop again if i didn't take off.

I was on a camping trip down on a beach, it was downpouring and wet the entire weekend (don't think that would contribute), i was playing in the mud and did a few hill climbs, it began to over heat once but i parked it and shut it off immediately when it did, was only running hot for maybe a minute, nearly maxed out the heat gauge, as for oil, i'm currently running 10w-40, just changed the oil in it before the trip, which is why i'm hoping the oil filter may be the cause of it all, there was a lot of negative talk about fram oil filters, i don't really remember what i stuck on it but i believe it may have been a fram.
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Unread 07-05-2013, 06:21 PM   #8
Mywrangler94
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With that many miles on it, and yes that's a LOT of miles, it could be anyone of the aforementioned problems. One of the causes I have come across in my searches is the O rings in the oil filter adapter. Seems a lot of guys have changed them, when their oil pressure plummeted, and it's helped bring oil pressure up as much 10-12 lbs. I'm not saying that its your problem, but a bunch of little ones can collectively cause a large one. Let us know.....
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Unread 07-05-2013, 06:22 PM   #9
cruiser54
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What brand of oil filter are you using?
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Unread 07-06-2013, 03:17 PM   #10
AdamZJL
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I keep forgetting to check the oil filter, but i've got an update. I took the Jeep for a drive today, went and played in the pit for a bit and drove around the subdivision.. After about 20 minutes of playing i noticed it was starting to drop a bit when stopped but only to about the 1/4 mark, it wasn't stalling out, check gauges light never came on, once it started doing that i drove it around for about another 5 minutes and it stayed the same, when coasting down slow enough to safely take a corner or coming to a stop sign it would drop down to around the 1/4 mark, slightly under once, but never went down to 0, after that i entered the powerlines (just easy atv trails), that go past my house from the other end of the subdivision and most of it i was moving very slowly, coasting down hills, or pretty well stopped, and it didn't drop below the 1/4 mark. I don't know if this info will help with the diagnosis at all but it's details i didn't have before. The check engine light is on (it was on before this started too though), i'm going to scan it to see if there's any codes relevant to the oil pressure issue.
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Unread 07-06-2013, 04:30 PM   #11
skyway0018746
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Sounds like worn out main bearings, change the sending unit and do the same ride as above and see if it changed
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Unread 07-06-2013, 08:24 PM   #12
cruiser54
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Quote:
Originally Posted by AdamZJL View Post
I keep forgetting to check the oil filter, but i've got an update. I took the Jeep for a drive today, went and played in the pit for a bit and drove around the subdivision.. After about 20 minutes of playing i noticed it was starting to drop a bit when stopped but only to about the 1/4 mark, it wasn't stalling out, check gauges light never came on, once it started doing that i drove it around for about another 5 minutes and it stayed the same, when coasting down slow enough to safely take a corner or coming to a stop sign it would drop down to around the 1/4 mark, slightly under once, but never went down to 0, after that i entered the powerlines (just easy atv trails), that go past my house from the other end of the subdivision and most of it i was moving very slowly, coasting down hills, or pretty well stopped, and it didn't drop below the 1/4 mark. I don't know if this info will help with the diagnosis at all but it's details i didn't have before. The check engine light is on (it was on before this started too though), i'm going to scan it to see if there's any codes relevant to the oil pressure issue.
Good chance you've got a bad oil sender. You can verify the oil pressure with a mechanical gauge rented from a parts house. When you get a spare 7.5 seconds, look at the oil filter brand. Some of them are absolute junk, aggravated by the fact that they're mounted upside down and sideways on our Jeeps.
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Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

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Unread 07-07-2013, 07:43 AM   #13
Armycherokee
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I was in the same boat as you my oil pressure would drop to zero then I changed my sending unit and that solved a some of my problem then I switched to mopar oil filter and I'm running 15w40 and I have no more problems like mentioned before it doesn't help that our filters are in crazy postions for example mine is upside down.
I also replaced my oil filter adpter Orings and that helped with a slight oil leak as well but also helped with my pressure problem. My oil pressure still is all over the place it's not as
Low as it was but moves to much for me I will be replacing my oil pump in the near future. Hope this helps you
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Unread 07-07-2013, 09:17 AM   #14
AdamZJL
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Does, a lot, my oil filter i can't see the logo on it due it's facing directly at the motor, but it appears to be just some cheap generic brand from a local parts store (one my mechanic goes to), i'll have to get an actual Mopar one and change it some day this week at work... don't like doing it in my driveway, i did once and oil ended up f*ck*ng everywhere lol. I was talking to a buddy of mine yesterday who said he's had the same problem on two of his three jeeps and it was the sending unit, so i'll change the sending unit, oil filter, and oil filter adapter O-rings, i'm already running 10w-40 so i probably won't worry about going to thicker oil.
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Unread 07-07-2013, 12:02 PM   #15
cruiser54
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Quote:
Originally Posted by AdamZJL View Post
Does, a lot, my oil filter i can't see the logo on it due it's facing directly at the motor, but it appears to be just some cheap generic brand from a local parts store (one my mechanic goes to), i'll have to get an actual Mopar one and change it some day this week at work... don't like doing it in my driveway, i did once and oil ended up f*ck*ng everywhere lol. I was talking to a buddy of mine yesterday who said he's had the same problem on two of his three jeeps and it was the sending unit, so i'll change the sending unit, oil filter, and oil filter adapter O-rings, i'm already running 10w-40 so i probably won't worry about going to thicker oil.
Good plan, but I'd only replace the O-rings if they're leaking.
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Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
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