Forum Discussion

colonelcorto's avatar
colonelcorto
Explorer
Apr 24, 2017

Hot Transmission, what can I do?

What I have: 1996 Fleetwood Southwind 35LS, 460EFI, E4OD, Banks headers, Transcommand, US Gears Dual Range (under/direct), Dana series 80 5.13, trans temp gage, 96k miles, 19,800 Lbs fully loaded (includes all passengers).

The E4OD was rebuilt a couple years ago by the previous owner, he burned it up while towing his car on a car hauler. I am sure he was over the 23,500 Lbs max GCVW for this coach. Also, I doubt he understood how to use the auxiliary transmission. He had the E4OD rebuilt by a shop out east and they also replaced the radiator, added the trans temp gage, and possibly installed the auxiliary trans cooler. This was about 6k miles ago. When I run on flat ground the gage reads at the top of the normal range (about 200 F). When I ascend mountains (plenty around Las Vegas where we live) it is in the 220 to 240 range. We don't tow a car and I can ascend the mountains easily enough by locking out OD and climbing in 3rd (low range on the US Gears when they are really steep) with only a few down shifts to 2nd. I can maintain 40 to 50 MPH at using this method but at the above mentioned temp.

The charts I have read suggest that I'll only get 20k - 40k out of the transmission at these temps. What is the best way to get them down? Can I mount a DC fan in the front of the cooler with a switch on the dash? Should I install a larger cooler (I have gobs of room)? Or will slowing down on the ascents solve the issue? I am sure that this summer's 100F+ temps will compound the problem.

If I can figure out how to upload pics I will post them. Thanks!
Class A
  • crasster's avatar
    crasster
    Explorer II
    Apr 25, 2017
    Some of these suggestions are easier said than done. The fan itself couldn't be just an electric fan, must be 12v and have a thermostat to cut on. Also should be durable (auto grade) for rain/weather, etc. I'd suggest just adding the cooler first to open venting and then go from there if needed.
  • crasster's avatar
    crasster
    Explorer II
    Apr 25, 2017
    Some of these suggestions are easier said than done. The fan itself couldn't be just an electric fan, must be 12v and have a thermostat to cut on. Also should be durable (auto grade) for rain/weather, etc. I'd suggest just adding the cooler first to open venting and then go from there if needed.
  • CharlesinGA's avatar
    CharlesinGA
    Explorer
    Apr 25, 2017
    All of the temp charts on the internet show fluid breakdown beginning by 220F or so and the life getting very short above that.

    I would get a LARGE transmission cooler with a built in fan that operates on a thermostatic switch, also built into it. There are a number on the market.

    What brand gauge is it? where is the temp sensor mounted? Do you have a deep aluminum pan installed to add additional fluid quantity to the transmission so it will run cooler, plus the cooling the aluminum pan offers.

    Chales
  • theoldwizard1's avatar
    theoldwizard1
    Explorer II
    Apr 25, 2017
    A number of years ago I actually worked in a transmission engineering department of one of the Detroit 3. Assuming the gauge is accurate, 240F IS hot, but it is not over heating ! If it stays under 250, just keep an eye on it.

    IIRC, typical "old fashion" ATF does not start to breakdown until about 275. Things go down hill pretty quick after that.

    If you want a bigger cooler shop for Earl's Performance Temp-A-Cure Fluid Coolers. Used on race cars for cooling engine oil but they are fine for ATF. Many sizes. It will like require custom brackets and hoses.
  • RLS7201's avatar
    RLS7201
    Explorer II
    Apr 24, 2017
    200 degrees is pretty much normal and acceptable for that transmission. The reason it heats when going down hill is because the torque converter unlocks when you tap the brakes. Under normal pulling conditions, the torque converter stays locked until you drop in to 1st gear.
    My 95 Bounder 460/E40D runs the same temperature range as yours. Mine was still working well at 140,000 miles but was pulled for rebuild when I put in the new stroker engine.

    Richard
  • rgatijnet1's avatar
    rgatijnet1
    Explorer III
    Apr 24, 2017
    colonelcorto wrote:
    It is located where it gets ambient air from the front grille in front of the condenser. There is about 18 inches between the cooler and the grille. Its only about 12 inches by 9 inches in size. Would moving it closer to the grille help?


    When you go slow, during a climb, there may not be enough air movement to provide sufficient cooling. I would replace that cooler with a larger one and add an electric cooling fan that you can switch on manually if the temps start to climb. Get one rated for 30,000 pounds GVWR.
  • colonelcorto's avatar
    colonelcorto
    Explorer
    Apr 24, 2017
    It is located where it gets ambient air from the front grille in front of the condenser. There is about 18 inches between the cooler and the grille. Its only about 12 inches by 9 inches in size. Would moving it closer to the grille help?
  • jplante4's avatar
    jplante4
    Explorer II
    Apr 24, 2017
    Where is the trans cooler? Is it in warm or ambient temp flow? Moving the cooler and adding a fan would be a possible solution.

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