1. #1
    Join Date
    Dec 1999
    Virginia Beach VA

    What temperature is too hot for my Automatic 42RLE Transmission?

    I just upgraded my transmission temp gauge, and I was wondering what you guys would consider the max temp (where you'd pull over). Mine seems to stay around 185°
    Last edited by TerryMason; 12-29-2011 at 03:22 PM.
    My 2005 Wrangler Build Thread

    “He who is without oil shall throw the first rod.” -Compressions 8.7:1

  2. #2
    Join Date
    Jul 2008
    Santa Clarita ,ca

    Re: What temperature is too hot for my Automatic 42RLE Transmission?

    keep in mind heat transfer metal to metal contact etc.. If your motor hits 220-230 its going to get hurt before your transmission. but safely speaking 215 is about as high as I would personally be comfortable with.
    You could always talk to your local trans shop for thier recomendation.

  3. Re: What temperature is too hot for my Automatic 42RLE Transmission?

    You might be able to go slightly Higher -- Under SEVERE Driving Conditions. Probably about -- 220F -- On a HOT Day - while climbing a hill! I would expect the Normal Transmission Temp. To be around: 180 to 195F. Several Factors come into play: 1. Thermostat Temp. (195?). 2. Do you Have Installed on your Jeep an: Auxillary Trans Cooler? 3. Driving CONDITIONS. -- These Factors. Will determine your. "Normal" Transmission Temp. Chrysler Factory Service Manual says: Temp. OVER 240F is OVERHEATING. But --- Let's. ASK this QUESTION: What HAPPENS as Transmission Temp. GOES UP?? Gentlemen: HERE IS THE CHART ---- Let's Call it: TRANSMISSION LIFE EXPECTANCY CHART -- OK?

    1. Trans. Temp. --- 195F - Low Heat; LONG LIFE - 75K+ Miles.
    2. Trans Temp---220F -- Warm --- But OK!
    3. Trans Temp--- 240F -- Varnish Forms! (Maybe pullOver!!).
    4. Trans Temp--- 260F -- Seals Harden (Bad - start damage!).
    5. Trans Temp --- 295F -- Plates Slip (Real Bad)
    6. Trans Temp----315F-- Seals and Clutches. BURN OUT ! VERY BAD -- Maybe 250-500 Miles ! TRANS FAILURE

    So the MORAL of the Story: KEEP UR TRANS COOL! LONG LIFE-- NO PROBLEMS! Hope this. Sheds a little light on this Topic. Happy New Year -- To All our fellow Jeepers! - JB
    Last edited by TerryMason; 12-29-2011 at 05:05 PM. Reason: formatting

  4. Re: What temperature is too hot for my Automatic 42RLE Transmission?

    What Jimbob said is very much so accurate. By keeping the transmissions internal components at a cooler temperature it allows for the machine to operate at the most efficient rate. Once the temperature begins to rise in a transmission, the internal components can expand and will eventually fail. My 42rle overheated completely and ultimately failed while I was pulling a trailer with a couple of ATV's loaded down.
    Last edited by TerryMason; 01-27-2021 at 02:36 PM. Reason: Link removed

  5. #5

    Re: What temperature is too hot for my Automatic 42RLE Transmission?

    What temperature is too hot for my Automatic 42RLE Transmission?-c0e88598-edff-4585-86a3-d5e4a6a11141.jpegOn another SUV build I added auxiliary PS and trans coolers to ensure the temps will not get too hot. Both coolers are in series with the OEM coolers. Both auxiliary coolers are hard mounted on custom brackets.

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