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Thread: 68RFE Thermal Bypass Valve?

  1. Top Of Page | #21
    Crshanta's Avatar

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    68RFE Thermal Bypass Valve?

    Quote Originally Posted by DUST1N View Post
    Do you know if allisons have this? My truck has been in the shop getting a trans so i have been pulling with my fathers duramax. When its down in the 30s or below his trans gauge doesnt even move past the 100 degree mark. Just always thought it was odd mine would get up to temp and stay there and his would always fluctuate.
    Allison’s up-to 2013 do not. Right from trans to the cooler.

    While it does not get really cold in PA, I would put on the winter front on Dmaxs when temps dropped below 40.

    That would get trans fluid to 110-150 empty or towing less than 10k between a outside temp of -5 to 40.

    With the new truck I am also using the winter front and will be installing a revmax bypasss or similar shortly.

    2018 srw 3500

  2. Top Of Page | #22
    Basic Member mud015's Avatar

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    68RFE Thermal Bypass Valve?

    I just replaced mine with a popular bypass block.

    While driving I noticed about 30 degrees cooler temps under normal town driving but while on the freeway under a full pull tuned and deleted the feed line to the cooler popped off of the block clips where in with the factory plastic retainer as well.

    Yeah it was a mess so if you are looking at doing the delete I would look at having lines made to eliminate this from happening.

    Just one more week link on the 68RFE.


  3. Top Of Page | #23
    captgpflorida's Avatar

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    68RFE Thermal Bypass Valve?

    I'd like to add my experience on the Thermal Bypass Cooler block.

    I have a 2016 Ram Outdoorsman.

    I purchase the truck in Aug 2019 Used with 88k miles.

    Its a 4x4 Crew Cab Standard Bed.

    I live in South Florida with usual temps 85F and always 90F plus in the summer.

    Since I took delivery of the truck I have been learning about Ram Cummins and all I can about the truck.

    I have monitored the Operating temps of the fluid and just couldn't understand why the Transmission 68RFE temps are always at 190 - 210F, just driving around town with no tow or payload.

    Just a few miles of driving the 68RFE temps reach 180F. Then driving on the highway at 75mph I would think the oil cooler will receive cooler airflow and lower the temps.

    Highway driving the temps will reach 205F. Then once I return to city driving, temp will even reach 215F at traffic stops. At the high 200F temps, I notice the transmission will downshift roughly.

    Seems between 3rd to 2nd gear upon reaching a stop, I would feel a "clunck" upon slowing down to a stop.

    I was told by other Cummins Ram owners that this was normal.

    A transmission "tune" will fix the shifting parameters.

    The truck came with the Ram Owners Manual (Thick large white book with 860 pages) Section of Maintenance: Page 784, states 6 speed trans operating temp are 170 180F.

    I also would ask other Ram Cummins owners about their temps when driving around town. Those whom paid attention to their gauges, stated Trans temps between 140 - 160F in town not towing.

    So I assumed something was wrong with my Transmission Thermo Valve.

    After reading many forums on this topic.. I decided to install the RevMax Thermo Bypass Valve.. Purchased on Amazon.

    Viewed several vids on YouTube on how to replace. The job was fairly easy, same skill set as changing oil and filter.

    Took about 40 minz taking my time. Used a large drip pan to collect ATF drip. About 3 quarts dripped out, I replaced with 3 quarts of ATF+4

    Temps now are 135F - 155F in the City. So far the highest temp Ive seen in 162F after a few hours driving on highway. No towing or payload.

    Also notice shifts are smoother. The clunky downshifting has reduced. I can't very if the bypass mod with cooler temps is the reason for smoother downshifting.

    I hope this info can help others with the research for their 68RFE temperature problems.

    My 2 Cents folks.


  4. Top Of Page | #24
    Ausloose29's Avatar

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    68RFE Thermal Bypass Valve?

    I installed the thermal bypass valve last week.

    I bought the ATS block: https://www.atsdiesel.com/ats2/produ...p?p=3100052392

    Easy install~30 minutes or less.

    I have the 68RFE transmission.

    You lose about 3/4 quart of fluid or less so I’d recommend to have a quart on hand to refill.

    The Aisin will lose more.

    The temp range is now 125-130 when daily driving versus the 165-170 that I had before.

    From what I read the factory valve is for colder climates that are freezing and below so most states shouldn’t be an issue.

    I’d recommend this switch and consider it an upgrade.

    Lowering temp increases the life of the tranny and the fluid within.


  5. Top Of Page | #25
    Rambling Rump Ranger! SyN's Avatar

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    68RFE Thermal Bypass Valve?

    Replaced mine @ the 1200 mile mark - It was the 1st & best logical mod as of today!

    After many years - I have never (heard about) or (read about) any one transmission failure due to lower then average ATF temps.
    Most were due to over heating or idiot abuse & neglected maintenance...

    Once again: My opinion to owners whom live in very cold or extremely cold climates - I would advise against install...
    But be diligent with your transmission maintenance...

    2017 Bighorn (Delmonico Red & Chrome) CC-HD2500-4WD-6.7L-3:42w/Anti-Spin
    Oil: -SHELL- Rotella T6 5W-40 & T5 15W-40 combo w/LF16035
    68RFE/BW44-46/Power Steering: -Red Line- C+ ATF
    Frontend & Rearend: -Red Line- SAE GL-5 75W-90NS
    Many Small Mods: Interior & Exterior
    Mileage: 28,541

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