Strange coolant temp behavior.

Discussion in 'KJ General Discussion' started by GitEmSteveDave, Jun 6, 2020.

  1. GitEmSteveDave

    GitEmSteveDave Full Access Member

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    Feb 23, 2018
    So I had the engine replaced end of last August and had Jeep flush and refill the coolant earlier this year. My previous engine always ran cool(would take like 5 minutes sitting at a light in traffic for it to hit 219-221 and the fan kick on), but this "new" engine seems to run hot(cooling fan kicks on when doing almost any city driving).

    Lately, since the temps have been hotter, I notice the temp creep up to 219-221, the fan kick on and it drops down to ~204, rinse and repeat, but then all of a sudden the temp will drop down to 199 and stay in that area for a long time and almost act like my old engine.

    Any thoughts on this?
  2. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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    Oct 24, 2008
    B.C. Canada
    Summer temps make my eyes glued to the temp gauge/ scangauge. I've often wondered why the jeeps temps can be all over the map.
    I have never tried, but have thought about removing the thermostat in summer LOL.
    I just have the electrical cooling fan & I think adding the clutch fan may stabilize temps better in summer especially.
    Driving conditions like stopped in traffic obviously heat things up good, and then the high speed electrical kicks on and temps drop, thankfully!
    Once you are moving everything seems perfect.
    Going slow especially climbing off road in 4x4 mode for an extend period is a wow heat. Hood louvers a great idea if you are summer off roading. Or just take the hood off ~!
    I pulled over before and lifted the hood for a few and gave it some revs and watched the trans light go off. Added the 42RLE PML pan with drain plug solved that.
    Many times when pulling the boat I wished that I had a manual override to continuous high speed fan only.
    If I had it my way, I surely would have programmed in a lower temperature setting for the high speed fan to kick in.
    What about a high speed impeller or performance water pump is one available?
    My last thought is this radiator is awfully small. All may be cured if we could we could just mount a larger capacity aluminum rad and faster dual fans up front !
    Calling Ron Davis rads, can you help with a real custom rad for my KJ??
    Last edited: Jun 7, 2020
  3. HoosierJeeper

    HoosierJeeper Gold Supporter/Admin Staff Member Administrator

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    Jan 20, 2009
    Western WI
    The mechanical fans helps a ton when you're in stop and go. It always runs and when you accelerate it sounds like a jet from the fan fully locking on.... and AC stays super cold always!
  4. renegade 04

    renegade 04 Full Access Member

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    Jan 3, 2014
    Albany New York
    I would buy an all aluminum radiator and call it a day. My jeeps runs 195 all day everyday.
    LibertyTC likes this.