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Oil Pump And High Pressure Issue - 1977 Cj5 - 5.0l

Discussion in 'Intermediate CJ-5/6/7/8' started by Charles Brown, Jan 17, 2020.

  1. Jan 17, 2020
    Charles Brown

    Charles Brown New Member

    Salem, OR.
    Joined:
    Jan 8, 2020
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    11
    In the process of bringing this piece of beast back to life. I'm so close to driving this awesome machine around!

    My current issue is high oil pressure. I noticed it on my last ignition. the (i'm assuming mechanical gauge) is hovering around 80psi (which is the max of the gauge). As it warms up I can see the needle going down a little bit but still hovers around 80 none the less.

    It's the 5.0L v8, i've been running 10w-40 oil and i've changed it three times now in my rebuilding process. the oil level is to the full mark cold. Today I pulled the pressure relief valve to see if that was messed up. I had to use a magnet to pull the little piston piece out, as it was a tad snug at the end. but it slides around in the chamber smoothly, its only till it gets to the end that it "snaps" in. So i'm not sure if that's my issue there because i'm not sure what normal is.

    I put it all back together and put in some 5w-40 to see if it would change anything and it did not. Luckily I don't have to drop the pan to get to the oil pump, but short of replacing the cover i'm not sure what else to do.

    Is my pressure relieve valve kind of "clicking" in the issue? is it the oil i'm using? What other tests can I do to figure this issue out?

    Thanks as always.
     
  2. Jan 17, 2020
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    Try another gauge - maybe it's reading faulty.
     
    Ol Fogie likes this.
  3. Jan 17, 2020
    Charles Brown

    Charles Brown New Member

    Salem, OR.
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    Jan 8, 2020
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    Is what I described for the relief valve normal? Should the gauge max out like that or just remain at zero if its faulty? Should also be mentioned that this jeep has been sitting for the better part of a decade.
     
  4. Jan 17, 2020
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    Who knows what might be wrong with it. But if it's electrical it something as simple as a loose connection or a shorted wire could do either of those things.
     
  5. Jan 18, 2020
    sterlclan

    sterlclan Member 2022 Sponsor

    exploring the...
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    the spring holds the valve in if it sticks at the bottom of the hole it cant move to bypass the extra pressure, it shouldn't stick . that said I would check pressure with a good known gauge before going too much further. the wifes 76 will read pegged full pressure or about halfway, I know it has pressure cause the pushrods flow oil, the electrical sender is bad on hers.I figure when it totally stops working I will fix it.
     
  6. Jan 18, 2020
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    I did have a pressure relief stick shut on my M-715, due to a NOS pump with fossilized cosmoline.

    But that blew the oil filter right off the engine. I can still see the oil stains on the garage wall.
     
  7. Jan 18, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

    Southern...
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    x2 on trying a new mechanical gauge first. You can just get a less expensive one at your local FLAPS and install temporally in the engine bay.
    Another thought when you changed oil did you use a good quality oil filter? some of the cheaper filters might have a problem with flow forcing the oil pump to rely on the by pass valve to keep the engine lubed, if my thinking is correct on how it works. could this cause higher pressure? anyone else know?
     
  8. Jan 18, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

    Southern...
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    Several years ago my brother had an old ford pu with a straight 6 engine. We changed the oil and filter. When finished we drove up the street and the power steering stopped working--hum, fluid level ok, all look normal. The power steering worked normal when sitting parked and engine at idle, when you increase engine speed the power assist would go away making driving almost impossible above idle speed. work on the problem for 3 days, changed PS pump no help, new hoses no help, even changed steering gear no help. nothing left to change. humm--humm.:study: now what to do, we were looking at the engine while it was at idle, revved up the engine and someone said-dang look at that oil filter its swelling up like a balloon when you increase engine speed. seems the steering drag link passed very close by the oil filter and when the engine speed was increased oil pressure increased as well and the filter was swelling up enough to press on the drag link making it hard to steer. The new filter was a cheap-o from the local service station as the FLAPS was closed that day. With only a light and no gauge we had no way to tell the pressure was excessive. Turns out the relief valve was stuck. Guessing the original oil filter was much better quality and probably would not swell with the excess pressure. Not all was lost at least he got a whole new steering set up.:D
     
  9. Jan 18, 2020
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    :shock:
     
  10. Jan 18, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Yeah,I would have never believed it could swell that much and not rupture if I had not seen it . It was swelling 1.5 inches or so!
     
  11. Jan 19, 2020
    4wealn

    4wealn Member

    Ontario, Canada
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    You could check the tolerance in the pump gears.
     
  12. Jan 19, 2020
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    I don't think there is any question a pump in good condition should be capable of producing high pressures.

    The question is if the relief valve is blowing off that normal over-pressure, or if the apparent condition is a gauge reading incorrectly
     
  13. Jan 21, 2020
    4wealn

    4wealn Member

    Ontario, Canada
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    Only reason I suggested this is I had lower than normal oil pressure and installed the midplate by melling along with a new spring and gears and my oil pressure jumped to 80-90 and would not come down. I removed the midplate and my pressure is now great. Just something to check. It had me baffled at the time but I think my tolerance was too tight causing the high oil pressure.
     
  14. Jan 21, 2020
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    My first new car was a '77 VW Scirocco, before they went to hydralic lifters. Cold oil pressure in cold temps was in excess of 120 psi. I blew up two Fram filters, back to back. The whole canister completely separated at the crimp both times. Mann filters never gave any problems.
    My guess is there is a faulty gauge on that 304.
    -Donny
     
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