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Transmission Fluid Cooling?

Discussion in 'The Hokey Ass Message Board' started by AAFD, Jun 26, 2010.

  1. AAFD
    Joined: Apr 13, 2010
    Posts: 585

    from US of A

    TH400 Transmission, Stock Converter
    Aluminum Cooler Lines to Stock Radiator ATF Cooler
    Inline Transmission Cooler on Return Line into Transmission
    Derale Deep Steel Pan with cooling tubes inside

    What's the optimum ATF temperature for daily driving?
    I heard 200* degrees is fine, anything over that is bad.
    Engine Temp stays around 180-190* degrees, so the ATF temp can only go up from there. I figure with the external inline cooler and tubed deep pan will drop ATF temperature quite a bit. Just trying to be preventative, no such thing as overkill, right?
  2. AAFD
    Joined: Apr 13, 2010
    Posts: 585

    from US of A

    Back up for the Sunday crowd...
  3. maniac
    Joined: Jul 11, 2005
    Posts: 539


    Other than the stock radiator cooler, I'm running the exact same setup, never had any problems with it in 20 years or so, don't have a trans temp gauge, but oil stays red and never smells bad.
  4. AAFD
    Joined: Apr 13, 2010
    Posts: 585

    from US of A

    Maniac, yeah I'm guessing it should be good. I'd like to run a gauge just to monitor temps, but unsure of what optimum temperature of the ATF should be.

    Pitts, the external trans cooler needs to be on the return line back to the transmission from the radiator cooler. Doing it the other way is kind of useless.


  5. ...I've run trans coolers only (not radiator coolers) for over 30 years on as many cars; mounting the cooler along side the trans on the inner framerail with no problems. Just mount it so it gets air around it as you drive and away from exhaust.
    I think this also lets your radiator work better as you don't add the trans heat to it.
    ...just my 2 cents,...don't really know what the trans temp should run ...
  6. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,307

    from Quincy, IL

    It seems to mme that if the manufacturers used radiator trans cooler only, except in heavy duty apps, then that must be adequate for normal use, meaning an average weight car with moderate engine power driven on the street. I have often wondered about 'proper' trans temps though, and considering most cars have 180 to 200 degree thermostats, the trans almost HAS to be running in that range. In aircraft, engine oil temps are intended to be no higher than the low 200's, but trans fluid and engine oil are no doubt formulated differently.

    I think the trans probably benefits from some sort of 'normal operating temp' as opposed to running way cool. If that is true, then I like your approach of running thru the radiator cooler, then aux cooler then back to trans..........basically what a factory tow package aux cooler does.

  7. Deuce Roadster
    Joined: Sep 8, 2002
    Posts: 9,519

    Deuce Roadster
    Member Emeritus

    My 2009 Silverado LTZ ( off topic HAMB I understand ... but as a referrence point ) has a factory tow package. It has a factory transmission temperature gauge. The transmission fluid is usually 80 degrees warmer than the outside weather temperature. :)

    When it is 90 degrees here in South Carolina ... the transmission temperature is usually 170.

    Even pulling up a long, steep hill with 7 thousand pounds of trailer load behind me ... I have NEVER seen the transmission temperature go above 208 degrees ( and it was 106 degrees outside :( )

    Because I have fairly " LOOSE " converters in both of my 32 Fords ... I have the extra remote cooler before the radiator. I believe that is another reason my 32's run cool. The fluid is COOL as it goes to the radiator and then the heat from the radiator ... helps the fluid get back to a 170/190 temperature range that MOST prefessional transmission experts suggest.


    I also put inline before the remote cooler ... a extra transmission filter :)
    I plumb it with hard line ( no rubber :eek: ) I think having the extra filter helps in two ways. 1 ) it increases the amount of transmission fluid in the system 2 ) it keeps any debris and trash from ever getting to the remote cooler and the factory filter in the transmission.

    :eek: :eek:

  8. 50dodge4x4
    Joined: Aug 7, 2004
    Posts: 3,535


    All I can tell you is I have a very big trans cooler on my plow truck and the fluid has not ran through the rad since this has been together. This truck has plowed snow, pulled trailers and been generally abused for over 10 years now. The trans has not had anything other then a recent fluid change in those 10 years. I suspect that trans sees a way larger fluid temp range (-30 to probably +200, truck water temp has been past 230 more then once) then most of your cars ever will and that trans is not showing any signs of damage. Gene
  9. HOT40ROD
    Joined: Jun 16, 2006
    Posts: 961

    from Easton, Pa

    Had a frame rail cooler in the 41 Ford with a temp gauge in the pan. Never got above 185.

    Just remember if your engine running at 180,190 or 200 and you trans is running through the radiator, that all the cooler the trans oil will get.
  10. big creep
    Joined: Feb 5, 2008
    Posts: 2,945

    big creep

    i run one without it going into the radiator, i have a be cool radiator so it has baffles in it, no room for a trans cooler. ive never had a problem. i think for older cars without computers it will be fine. my buddy has a transmission shop, and he said it should work fine!
  11. Darkharts
    Joined: Aug 24, 2004
    Posts: 119

    from Corona

    On may daily i went over kill since it takes allot of abuse- just a big cooler and bypass of the radiator. My tranny guy said it can also cause issues since like the motor it wants a minimum temperature. I used to work down by the beach and it can soak up condensation and if not allowed to heat up enough to boil it off it could do some damage. Now on a computer controlled unit i would worry more but due to the cost of my rebuild for my olds hydramatic i put a termostat in just to be safe. I remember it opening at about 180. Im sure over heating is like 95 percent of issues but im just lucky so now its safe on both sides.

    hope it helps,

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