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2000 Suburban 2500 Tranny cooler reading hot when towing

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by skongolf, Mar 25, 2013.

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  1. skongolf

    skongolf New Member

    I have a 2000 Suburban 2500 4x4 with 180K miles. Last weeekend I was towing my boat which weights about 4000lb and the tranny cooler reading started getting pretty high, up to around 250 when going up some grades. When I got to the flats it went down a little but it stayed around 220 the entire time. My radiator gauge never moved from 190 which it never does. I did replace the tranny fluid about 25K ago so I am sure it is OK. I am just wondering if a Tranny cooler can go bad. I am sure the current cooler is stock and it does not look that big at all. What would be the best thing to look at first? This weekend it was only 82 degrees out and it was running hot so I am a little worried what will happen when the temps hit the 100's. Thanks in advance for any help.
  2. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    As you mentioned, the Stock Factory Transmission Cooler is Small, I also was concerned about my Transmission Temps reaching 180, 190 and at times, Just over 200 Degrees, when Towing my Boat,

    IMO the Best Thing to do, is to go with a Larger Aftermarket Transmission Cooler....which is what I did.....so I Swapped out the Small Factory Trans. Cooler, and went with a Larger Cooler, Called a 40K Transmission Cooler, below is my Thread, regarding the removing of Factory Cooler and the installing of the 40K Cooler.


    Since installing the 40K Cooler, my Transmission Temps, when Towing my Boat have never gone over.....160 Degrees, this has been the Best Up-Grade I've done with helping to keep my Trans. Temps Down when Towing!!!.....but also one of the easiest Swaps I've done.

    http://www.gmtruckclub.com/forum/showthread.php/88250-New-Transmission-Cooler
    Last edited: Mar 25, 2013
  3. skongolf

    skongolf New Member

    Thanks for the info. I skimmed your article, so did you just add this cooler along with the factory or just replace it? If I replace the factory one isnt it just a case of unbolting and removing the lines from the old one and install the new one? I thought I saw something where you cut the metal tranny line underneath. Unfortunately the pics from your install don't show up on my computer.
    Thanks
  4. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    I Removed the Factory Trans. Cooler all together, and then mounted and installed the 40K Cooler, here are the pictures of the......removing of the Factory Cooler and installed of the 40K Cooler, and the 3rd picture down, it shows how I mounted the Transmission Lines using the 2 Inverted Flair Fittings and Compression((Brass)Fitting onto the New Transmission Cooler......hopefully you will be able to See/View them??



    Factory Transmission Cooler

    [​IMG]
    New True Cool 40K Installed With New EAD Upper and Lower Mounting Brackets

    [​IMG]


    Install of the Inverted Flair Fittings to both of the Transmission Hard-lines
    [​IMG]


    Install of the Compression(Brass)Fitting........to be able to Spin the Passenger Side Hard-Line 180 Degrees to Line-Up/Fit onto the Threads of the 40K Cooler
    [​IMG]






    Below are the Items/Parts used in the Install of the Transmission Cooler,

    True Cool 40K Transmission Cooler
    [​IMG]




    The 2 Inverted Flair Fittings and Compression((Brass)Fitting that were supplied in the EAD Kit,

    [​IMG]

    [​IMG]

    Mag-Hytec Transmission Pan
    http://www.mag-hytec.com/transmission.htm




    Last edited: Mar 25, 2013
  5. skongolf

    skongolf New Member

    Seems fairly straightforward. My concern was having to cut into the hard line underneath that I saw in another video online.
  6. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    I had no problems with cutting the hard-line, to install the Compression Fitting, and have had no Issues/Problems with it since.....and it is "fairly straightforward".....also I'm guessing you were able to view the photo's above??....:great:

  7. skongolf

    skongolf New Member

    So I just went and checked and I do have the oem cooler. It is tiny! anyway, did you run two new cooler lines because on second look at your pics, they look different. Is there a description of how you did the lines anywhere? Hate to ask all the questions, but I will be doing this myself. Thanks
  8. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts


    The Only Mod(Cutting)of what I call the Passenger-Side Hard-line, and that was it....the factory hard-lines are the some ones, I didn't add any new hard-lines.

    This picture is of the Factory Cooler, notice where the Passenger-Side Hard-line is located and the Driver-Side Hard-line

    [​IMG]

    In this picture notice where the Pass-Side Hard-line is now, after the Install of the Compression(Brass)Fitting....I was to be able to Spin the Passenger Side Hard-Line 180 Degrees to Line-Up/Fit onto the Threads of the 40K Cooler
    and the Driver-Side Hard-Line is in the Same Spot, as it is in the picture above.
    [​IMG]




    In this photo, you can see the Compression Fitting, on the Passenger-Side Line,
    and then the Install of the Inverted Flair Fittings to both of the Transmission Hard-lines
    [​IMG]


    Hope this helps you out, regarding your Questions???
    Last edited: Sep 4, 2013
  9. skongolf

    skongolf New Member

    Sure does. How hard was it to cut the line? Did it pull up enough to get a pipe cutter on it? Also did the mounting brackets come with the kit or did you have to make your own? I definately plan on doing this soon. Thanks again for all the answers.
  10. j cat

    j cat Active Member 1000 Posts 100 Posts

    since you have had this vehicle for some time now and suddenly you notice that the tranny temp of 190 deg f which is normal expected now is in the 250 deg f range I would say that the transmission is slipping. now another reason this can occur is did you tow in 4th gear ? towing in 4th gear and not in tow mode will cause internal tranny temps to rise.

    installing a "huge" tranny cooler is a good upgrade , if you plan on towing in 100 deg f temps. it will also lower the engine temp. the only problem I found with installing a huge cooler is , the heater temp in cold weather takes much longer .

    I also noticed more power when towing in the hot weather.

    cutting the tubing lines you need a tubing cutter . do not use any saw . then if required you use the proper hoses or get more hard lines to complete the install using the compression fittings. do not over tighten these type fittings . the small seating part can crack. to secure these properly you tighten the nuts so they are snug then turn 3/4 of a turn . then take the fitting apart and check for proper seating position. on re-install tighten the fitting until you feel its not compressing those seats into the tubing any more .

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