I had my transmission rebuilt about 5 months ago in my 1999 Dodge Durango and now the transmission keeps overheating when I tow a lite model trailer. I pulled this trailer for years before having the transmission rebuilt with no problems. I even paid an extra $400 to have a drop cooler put on when I had the transmission rebuilt that is supposed to keep the temp down. I have taken it back three times now and they have yet to remedy the problem. If anyone has ideas on what is causing this, please share.

 

Does the transmission overheat only when the trailer is hooked up? Or all the time.

 

The transmission does not overheat during normal commuting, but will overheat even without towing if I am driving for an hour or more and driving up inclines at 65mph or higher which isn't that often. The biggest problem is however when I am towing my trailer. I just don't understand why I never overheated over the last several years pulling the same trailer, and then I get the tranny rebuilt and even add a drop cooler to it and now it consistently overheats.
One explanation that Cottman Transmission gave me for the problem is, (and I hope Iexplain this right) that the TCC in the transmission continuely shifts in and out while I'm driving causing extra heat in the transmission. They said it was a computer problem and that I would have to have my computer re-flashed. I spent $94 to have that done, and my next trip out, it overheated again. Thanks for your time.

 

Have you given your cooling system a good flush??? How about you t-stat? It may just be partially stuck. My OEM t-stat would only open partially so it was pretty weird when I would start to try and overheat. I was just lucky enough to go for the cheapest repair first in the cooling system and that was my issue.

Another question for you, do the tranny lines run through the radiator at all??? I am asking you this because after a rebuild you should replace the radiator as the old TC can throw a lot of crap into the lines and plug up your radiator. When this happens you can flush it all you want but there is still crud in there because you cannot do a reverse flush which would get everything out. Keep that in mind. I went through 3 rebuilds on my tranny (2 of them were under warranty from the 1st) and the last AAMCO actually knew what they were doing and told me to replace the radiator or he wouldn't cover my tranny. Do a search on the forums and you will find my issue, that was a fun month. [:'(]

 

Also adding to what mean green had said on the radiator, Do you have an electric fan as well as the engine fan? If you have an electric fan and its not coming on the radiator and cooling system will get hot.