Thread: Oil Pressure

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  1. #1 Oil Pressure 
    Senior Member grandmaster's Avatar
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    Well ive been driving my jeep around a bit sense i got my long arms/axle/tcase done and it seems to be running good and handles much better too. But the other day when i was driving i noticed my oil pressure was really high. I figured high oil pressure was better then no oil pressure, but my gage is maxed out. At Idle it sits at the line right before 80, and when i press on the gas it shoots up to 80 (as high as the guage goes). Im heading down to napa to pick up a sending unit to see it that fixes the problem. Any ideas of why it could be so high??

    Oh another thing to add is it dropped the other day when i was driving to just below 40 and then shot back up and then down and then back up to 80 again...

    Thanks in advance.
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  2. #2 Re: Oil Pressure 
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    mines goes up almost to 80 as well..Let me know what fixes the problem for ya, I am just gunna change the oil, see if that helps
    95 Rubicon ZJ-60/14b-40" LTBs on 17" ORO beadlocks-full hydro
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  3. #3 Re: Oil Pressure 
    Junior Member 94limited's Avatar
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    could actually be in the gauge too if the sending unit doesnt fix it
    94 zeej 5.2 np231 swap dynomax exhaust 2 inch bb and 31s slowly but surely
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  4. #4 Re: Oil Pressure 
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    mine does it all the time if im sitting at a light letting the car idle the guage sits in the middle. As soon as i give it any gas it shoots strait to the max. Its been doing it for over a year now so i figure nothing is going wrong. It all started on a wheeling trip. If you get the problem tracked down post up. It would be nice to know whats going on with the oil when im out.
    95 zj, KOR 7" long arm kit, lockrights front and rear, 285/75/16 (32.9x10.3) on rock crawler 16x8x4.5bs, kevins track bar with a home brew conversion, K&N FIPK, and Rubicon Express gen II discos.

    Ready for install... home brew sliders
    http://www.mallcrawlin.com/forum/sho...hlight=sliders
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  5. #5 Re: Oil Pressure 
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    its the sending unit. when it doesnt work at all it will just peg at 80. it could also be the elec connector to the unti, so check that first. you need a special socket to replace the sending unit (at least on the 4.0)
    '93 ZJ 4.0 w/ AX15 and slightly modded and many unreasonably farfetched plans
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  6. #6 Re: Oil Pressure 
    Senior Member grandmaster's Avatar
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    Ok, well i grabbed the sending unit from NAPA and I'm going to put it in on Sunday when i get a minute. Been packing for college so I've been pretty busy. We will see if it fixes the problem and I will post up when i know for sure. Unless Comanchefreak is right then we already know the answer. Do you think you can get that special socket through autozone on there loan a tool thing?
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  7. #7 Re: Oil Pressure 
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    Hey guys, i put in the new sending unit just now and it dropped it down to about 60 at idle, still isn't were it was, but is an improvement. And i figure a little high oil pressure is better then no oil pressure. I got the sending unit at napa for $20 bucks, but that was on my dad's old account, normal price was about 47 dollars and the part number is OP6695 (for the 4.0l). I called auto zone and they wanted $24 for it and Pep boys wanted $28. I just used a cresent wrench to get it off and put the new one on, and put the old one back in the box and will keep it as a spare just in case.
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  8. #8 Re: Oil Pressure 
    Senior Member dangerousdave's Avatar
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    cool. i think ill do that when i do my engine swap. I figure it cant be any easier to get to then right then. thanks for the part number.
    95 zj, KOR 7" long arm kit, lockrights front and rear, 285/75/16 (32.9x10.3) on rock crawler 16x8x4.5bs, kevins track bar with a home brew conversion, K&N FIPK, and Rubicon Express gen II discos.

    Ready for install... home brew sliders
    http://www.mallcrawlin.com/forum/sho...hlight=sliders
    Dr. Mambo
    http://www.mallcrawlin.com/forum/sho...ighlight=mambo
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  9. #9 Re: Oil Pressure 
    Senior Member grandmaster's Avatar
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    Your probably right, and if you have the tool to take it in and out it will make the job 1000 times easier. Its harder then hell to fit a big cresent wrench in there.
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  10. #10 Re: Oil Pressure 
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    This is from Alldata. Just a way to test your sending unit before you spend the money to replace it just in case. Thought maybe it would help.

    1. Place ignition switch in On position, then disconnect oil pressure sending unit connector and observe gauge. Needle should move to high end of scale.
    2. Connect a jumper wire between sending unit connector and ground and observe gauge. Needle should move to low end of gauge.
    3. If gauge performs as specified, replace sending unit; if not, proceed as follows:
      1. Remove jumper wire and place ignition switch in Off position, then disconnect battery ground cable.
      2. Remove instrument cluster and dash pad, then disconnect printed circuit connector and probe cavity C9 for continuity to ground. If continuity exists, repair short as necessary; if not, continue with procedure.
      3. Check for continuity between cavity C9 and sending unit connector. If continuity exists, replace gauge; if not, repair open circuit as necessary.
    -95 ZJ 5.2, 4.5" Lift, 33 12.50 STT's, 231swap, Rear Detroit Tru-Trac,JKS Quicker discnnects, KOR Track bar front. jks rear, and more.
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  11. #11 Re: Oil Pressure 
    Senior Member grandmaster's Avatar
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    Thats a bit different...a lot harder then anything i did. I just assume spend the $20 dollars replacing the sending unit, and if that doesn't fix it you take it back. Or you leave it in and move the wires around to see if it is a short somewhere in the engine compartment. If that doesn't work then you have to assume there is something wrong with the guage or the wiring that goes to the guage. Thats just the way i trouble shoot things, and just replacing the sending unit worked for me But thanks for the post, it could be helpful to some and i assume there is pictures of the wires they are talking about and such??
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  12. #12 Re: Oil Pressure 
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    No problem. As far as pic's I will have to get back on there and check. If anyone needs them I will try to get them up if they are on there. I do remember seeing once that high oil pressure readings was a common thing with the ZJ's. Couldn't find it on there when I looked last though. But it was in the chrysler parts systems computer before.
    -95 ZJ 5.2, 4.5" Lift, 33 12.50 STT's, 231swap, Rear Detroit Tru-Trac,JKS Quicker discnnects, KOR Track bar front. jks rear, and more.
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  13. #13 Re: Oil Pressure 
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    where should the 4.0 be at idle and driving
    1994 zj 4.o 3.73's hella 500's custom front bumper homebrewed coldair intake(registered on computer)and a cherrybomb
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  14. #14 Re: Oil Pressure 
    Senior Member grandmaster's Avatar
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    At Idle mine is between 40 and 60, when you press on the gas it almost hits 80...but not quite
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  15. #15 Re: Oil Pressure 
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    if it goes below 40 is that bad
    1994 zj 4.o 3.73's hella 500's custom front bumper homebrewed coldair intake(registered on computer)and a cherrybomb
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  16. #16 Re: Oil Pressure 
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    I wouldn't say it is bad, but it cant be good. High oil pressure is better the low oil pressure or better yet no oil pressure.
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  17. #17 Re: Oil Pressure 
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    The WJ oil pressure guage in the dash is a dummy guage. IT DOES NOT show the actual oil pressure of the motor. Our oil pressure guage recieves a voltage thru the system and makes an indication of oil pressure so we all feel good about it. The PCM uses the correct reading, from the correct sending unit from MOPAR, to make indications of your check engine light. If your check engine light is not on and you are not getting a code (high/low oil pressure) then your pressure is above 13 psi and lower then 75 psi. The only way to measure actual pressure is from a wet guage. Further more the guages on our dash are not caibrated.
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  18. #18 Re: Oil Pressure 
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    Quote Originally Posted by blk01WJ View Post
    The WJ oil pressure guage in the dash is a dummy guage. IT DOES NOT show the actual oil pressure of the motor. Our oil pressure guage recieves a voltage thru the system and makes an indication of oil pressure so we all feel good about it. The PCM uses the correct reading, from the correct sending unit from MOPAR, to make indications of your check engine light. If your check engine light is not on and you are not getting a code (high/low oil pressure) then your pressure is above 13 psi and lower then 75 psi. The only way to measure actual pressure is from a wet guage. Further more the guages on our dash are not caibrated.
    What did we ever do before you arrived to chime in on threads from nearly two years ago?
    04 Dub -- Longarms, JK44, 9" ARB's etc.
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