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 Post subject: Oil pressure drop while Idling
 Post Posted: Mon Dec 07, 2009 12:24 pm 
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Paul Bunyan
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Location: Indiana
My el conquistador has a grand cherokee 4wd with the 4L and he said that when its idling in park, the oil pressure will drop and his check engine light will come on, but if he shifts into neutral and gives it some gas, it'll go back up to normal. He said that it drives fine, and he has no issues when driving it either. Any ideas?

explanation of VIN #
1 Manufactured By DaimlerChrysler Corporation
J Jeep
4 MPV (Multi-Purpose Vehicle)
G 5001-6000 lbs.
W Vehicle Line (North America) = Grand Cherokee 4WD (1999-2004)
5 1999 = Laredo
8 4dr Sport Utility
S 4.0 Liter
3 check digit (verification letter or #)
X 1999
C Assembly Plant - Jefferson North Assembly Plant (Michigan, USA)
659757 Vehicle serial number

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 Post subject: Re: Oil pressure drop while Idling
 Post Posted: Mon Dec 07, 2009 12:37 pm 
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freezes his batteries off
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I had a Ford Ranger that did the same thing. The problem with it was the pick-up screen in the pan was gummed up. With the engine at a higher rpm it would suck the oil up enough, but at idle it couldn't. I am not sure if there is a screen on the pick-up, but I would think there probably is one.

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 Post subject: Re: Oil pressure drop while Idling
 Post Posted: Mon Dec 07, 2009 12:41 pm 
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Paul Bunyan
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99stompertj wrote:
I had a Ford Ranger that did the same thing. The problem with it was the pick-up screen in the pan was gummed up. With the engine at a higher rpm it would suck the oil up enough, but at idle it couldn't. I am not sure if there is a screen on the pick-up, but I would think there probably is one.


if that were the problem - than the best way to fix it is to....drop the pan and clean it out? Or is there a solvent that he can try running through the jeep for 3000 miles? or just till his next oil change?

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DD: '96 Chevy K2500HD, ext. cab, LB, 4x4, 5 sp, PMD relocate, air filter retrofit, Banks Exhaust, 6.5L "F" diesel, Hideaway gooseneck hitch, Rear bumper hitch, Pyro Gauge, Boost Gauge, custom fog lamps mounted on a custom front hitch, DIY wastegate, A/C delete.

Wish List: some sort of scangauge, muffler & CAT delete, Walbro fuel pump & marine fuel filter, Feed the Beast mod (have fittings already)
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 Post subject: Re: Oil pressure drop while Idling
 Post Posted: Mon Dec 07, 2009 12:43 pm 
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freezes his batteries off
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I changed the pick-up tube. I tried to clean it, but the new one was not that much $ and I wanted to make sure I fixed the problem!

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 Post subject: Re: Oil pressure drop while Idling
 Post Posted: Mon Dec 07, 2009 4:45 pm 
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spackled
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Gump01 wrote:
99stompertj wrote:
I had a Ford Ranger that did the same thing. The problem with it was the pick-up screen in the pan was gummed up. With the engine at a higher rpm it would suck the oil up enough, but at idle it couldn't. I am not sure if there is a screen on the pick-up, but I would think there probably is one.


if that were the problem - than the best way to fix it is to....drop the pan and clean it out? Or is there a solvent that he can try running through the jeep for 3000 miles? or just till his next oil change?


For some more info on cleaning the inside of the engine out, check this post...
viewtopic.php?f=59&t=20126 (sludge!!, in the CJ section)
Just be aware that if you decided to try a motor flush, it's not a 3000 mile kind of thing. It's more like 5 min. at idle and then change the oil, or you risk wiping out the bearings. And, if there is a lot of sludge inside the motor, it can make the problem worse....

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 Post subject: Re: Oil pressure drop while Idling
 Post Posted: Mon Dec 07, 2009 5:19 pm 
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Tang Soo
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Location: NE Indiana
it could be the pickup, it could be the oil pump is wearing out, it could be the main bearings are going out. if a flush of some type doesn't help, i would pull the pan, check the screen, plastic gauge a few of the mains, and/or change the oil pump...

is there any other noises or anything that is making?

you said the check engine light is coming on? have you pulled the code?

mac 'never seen a check engine light for low oil pressure' gyvr

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 Post subject: Re: Oil pressure drop while Idling
 Post Posted: Mon Dec 07, 2009 5:28 pm 
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Paul Bunyan
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Location: Indiana
its not my jeep and my el conquistador just told me about it this morning. I talked to chuck and googled it, and he's going to try the oil pressure sensor and see if that works. Seems to be a common replacement part. I'll pass this information along if that doesn't fix the problem.
Thanks!

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DD: '96 Chevy K2500HD, ext. cab, LB, 4x4, 5 sp, PMD relocate, air filter retrofit, Banks Exhaust, 6.5L "F" diesel, Hideaway gooseneck hitch, Rear bumper hitch, Pyro Gauge, Boost Gauge, custom fog lamps mounted on a custom front hitch, DIY wastegate, A/C delete.

Wish List: some sort of scangauge, muffler & CAT delete, Walbro fuel pump & marine fuel filter, Feed the Beast mod (have fittings already)
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 Post subject: Re: Oil pressure drop while Idling
 Post Posted: Mon Dec 07, 2009 7:51 pm 
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freezes his batteries off
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I thought about the oil pressure switch earlier this afternoon, but was to busy to post until now. That's probably the cheapest place to start!

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 Post subject: Re: Oil pressure drop while Idling
 Post Posted: Mon Dec 14, 2009 4:36 pm 
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Thread Necromancer
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is his engine comsuming any oil?
My TJ did that... main bearings were going out, so I rean 50 weight in it, and traded it off...

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 Post subject: Re: Oil pressure drop while Idling
 Post Posted: Thu Mar 22, 2012 3:59 am 
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n00b
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So this might be an oil issue not entirely on the mechanical of the engine? Maybe you should replace the oil on the right mileage instead of overusing it right?

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