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Help with low oil pressure 4.0

Discussion in 'Wrangler TJ (1996-2006)' started by Lorado, Aug 27, 2022.

  1. Aug 27, 2022 at 5:59 PM
    #1
    Lorado

    Lorado [OP] Member

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    Hi,
    A few months ago I bought a 97 Tj 4.0 4speed 132k from a friend who said it had sat for a year.
    After changing the oil, and a quick tune up it drives well but I quickly noticed a low oil pressure issue after about 10 minutes of run time. The gauge would drop to about 7psi and stay there regardless of rpms.

    I changed the gauge sender, didn't help, today put a mellings high volume oil pump in it and still no change. I did clean up the pan(half inch of sludge) and cleaned out the feed tube to the filter/gauge sender with a couple long zip ties.
    Im running Valvoline full syn 10w30 w a full qt of Lucas stabilizer.

    Has anyone had experience with this? I apologize if this is a usual issue and there are post about it already. New member and first time jeep owner.

    Thanks for your help and time!
    Chris

    IMG_20220504_170414124.jpg
     
  2. Aug 27, 2022 at 8:20 PM
    #2
    cpttuna

    cpttuna Well-Known Member

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    ss exhaust-viper coil
    have it checked with a mechanical gage. Look for leaks.
     
  3. Aug 27, 2022 at 8:30 PM
    #3
    Lorado

    Lorado [OP] Member

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    I just ordered one that will be here Thursday.
    Thanks!
     
  4. Aug 27, 2022 at 8:52 PM
    #4
    aggrex

    aggrex Well-Known Member

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    Tuffy>AEV>TTO>JW>STech>EVOcage>MagnaFlow>SpiderTrax>RockHard>TF>SpringTail>67design>Bolt>GPCA>Curt>
    The underlying issue could be the "sludge" found in one of your pics of the oil pan. Some ports or oil passages may be clogged or semi-clogged. Remove the valve cover to get another visual and/or run some motor flush agent.

    p.s. nice TJ otherwise
     
  5. Aug 27, 2022 at 9:01 PM
    #5
    Lorado

    Lorado [OP] Member

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    Thanks! I do need to do a valve cover gasket as it has a light leak. I used a light down the oil fill and the top of the motor from what I could see looked ok. But time will tell when I get the cover off. Also, I ran sea foam in it before draining the oil for the pump change and plan on changing the oil again soon to see how dirty it gets after light running. I have several things to address with it, but first things making sure it's safe to drive.
     
    aggrex likes this.
  6. Aug 31, 2022 at 4:45 PM
    #6
    Lorado

    Lorado [OP] Member

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    The mechanical gauge arrived a day early and the oil pressure does indeed drop to 7psi at idle when hot. The factory gauge showed that it wouldn't increase from there, but the mechanical shows it increases to 50psi at around 3k (possibly higher, but that's as high as I revved it).
    Would It be ok to go from 10w30 in it now to 15w40 and see from there? I'm seeing on other forums that main bearings seem to be the most common culprit. The problem though, budget constraints and the need to do repairs myself with limited experience.
     
  7. Sep 8, 2022 at 2:44 PM
    #7
    Justanotherjeeper

    Justanotherjeeper Well-Known Member

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    paid cash for it.
    Oil viscosity won’t fix the problem you are describing, Lorado, unfortunately. Although, a heavier oil may help until you get it repaired. It sounds like you need a new engine. I’m a firm believer in low km junk yard engines over rebuilds. Find a knowledgeable person in your local 4x4 community, and offer them a few bucks to help you do the swap. It’s not that big a deal and a good project. Take your time, and strive for perfection. Junk yard engines aren’t expensive, so the whole project should be quite doable. Your Jeep will be a like a new vehicle when you’re done with it.
     
    JKBob 25 likes this.
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