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Overheating

Discussion in 'Early CJ5 and CJ6 Tech' started by shaun, Aug 19, 2022.

  1. Aug 19, 2022
    shaun

    shaun Member

    Lebanon, Ohio
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    Oct 15, 2015
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    So I have a 225 with 4bbl carb and elect. Push fan because I wanted to go with electric and it doesn’t fit with upgraded radiator. But my thermostat is a 180 and I am running 250 on my gauge!! I also see my oil gauge is only reading 10-20. I’m thinking they run hand in hand low oil pressure more friction more heat. Am I wrong? Thoughts ????
     
  2. Aug 19, 2022
    Stakebed

    Stakebed Member

    BFE Lake Co.
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    Aug 2, 2022
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    More like high engine temp often results in lower oil pressure due to oil thinning out.

    BTW, pusher fans are notoriously inefficient.
     
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  3. Aug 19, 2022
    dnb5853

    dnb5853 Member 2021 Sponsor

    Grand Mesa, CO
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    Does your lower radiator hose have a coiled wire (spring so to speak) inside of it?
    This wire keeps it from collapsing during high volume transfers.
     
  4. Aug 19, 2022
    scoutpilot

    scoutpilot Member

    Asheboro, NC
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    Jun 7, 2014
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    Not enough information to even guess the problem. Engine history? Correct radiator? Running Lean? Timing?
     
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  5. Aug 19, 2022
    Downs

    Downs Rattlecan All The Things!

    Hunt County Texas
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    Jul 25, 2020
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    What "mode" is it overheating in. While you are sitting still or very low speed or at higher road speeds?
     
  6. Aug 19, 2022
    shaun

    shaun Member

    Lebanon, Ohio
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    Oct 15, 2015
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    Yes
     
  7. Aug 19, 2022
    shaun

    shaun Member

    Lebanon, Ohio
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    Oct 15, 2015
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    High speed like 30+
     
  8. Aug 19, 2022
    shaun

    shaun Member

    Lebanon, Ohio
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    Engine has great vacuum and when I had it 5 yrs ago when I was rebuilding the jeep I found I needed to replace the intake manifold, couldn’t find one for a long time for a good price so I went to 4 bbl 390 cfm, since then it was running great in the garage or down road. Oil pressure never went about 10-12, timing is 10 degrees BTDC , radiator is a little thicker than original and don’t think it’s running rich. No gauge but want to install one for tuning
     
  9. Aug 19, 2022
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Hills of NH
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    Checked your temperature gauge against a "known good" instrument?

    250ºF is well above boiling point....
     
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  10. Aug 19, 2022
    3b a runnin

    3b a runnin Active Member 2023 Sponsor 2022 Sponsor 2021 Sponsor 2020 Sponsor

    virginia
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    What is the cfm rating on the fan that you are using? Small fans that only 12-1500 cfm are not enough.
     
  11. Aug 19, 2022
    Downs

    Downs Rattlecan All The Things!

    Hunt County Texas
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    So a good rule of thumb when diagnosing overheating is that low speed overheating is usually caused by an airflow issue and high speed overheating is generally caused by a water flow issue. This isn't the end all be all for troubleshooting overheating and is just a good place to start. If it's only overheating over 30 I'd be looking close at the radiator and water pump.
     
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  12. Aug 19, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Is a pusher fan one of those mounted on the outside of the radiator?
     
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  13. Aug 19, 2022
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    Yes sir.
    Junk in my opinion.
     
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  14. Aug 19, 2022
    Fireball

    Fireball Well-Known Member 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Pullman, WA
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    Also make sure the mechanical advance is working in your distributor 10 degrees base timing is good, but it should be up around 35 degrees at 2000 rpm.

    As noted, I would be suspicious of the guage. 250 is right at the boiling point with a 13lb radiator cap. If it's really at 250, I suspect it would be pushing steam out the overflow tube.

    How fresh is your radiator? Could be clogged tubes.
     
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  15. Aug 19, 2022
    scott milliner

    scott milliner Master Fabricator

    Seattle Wa.
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    Dec 17, 2002
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    I see you have an M38a1 Grill. I cut 1" out of the grill and put dual 12" electric fans on the engine side of the radiator.
    It's a three-row radiator. I can run all day without the fans running. I only need the fans when I drive slowly. My fans have a thermal switch.
    They come on at 210 degrees and shut off at 195 degrees.
    [​IMG]
     
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  16. Aug 20, 2022
    shaun

    shaun Member

    Lebanon, Ohio
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    It’s a large 17” fan that just made fits in my grille. I believe it’s a high output fan. Ill have to check again
     
  17. Aug 20, 2022
    shaun

    shaun Member

    Lebanon, Ohio
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    I was thinking my water pump could be bad, I have a spare in garage I may have to look at that.
     
  18. Aug 20, 2022
    shaun

    shaun Member

    Lebanon, Ohio
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    It was pushing fluid out overflow tube.
     
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  19. Aug 20, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Are you sure your thermostat is opening properly? Have you started your engine when cold and felt the upper radiator hose to see when it starts getting warm due to the thermostat opening? What is the level in the radiator when the engine is cold?
     
  20. Aug 20, 2022
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Hills of NH
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    If the cooling system was recently drained and re-filled, an air pocket may be the cause.
     
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