After getting the run around at local GM dealers I went to a Cottman Transmission shop and had a TRU-COOL LPD-4490 12”x 11”x 3/4” transmission cooler installed. Around town the transmission cooler lowered the transmission temperature about 25 degrees.

On a recent1,500 mile round tripbetween Portland, ORand Fallon, NV area towing a tandem axel trailer with a gross weight of about 5,000 pounds the cooler seemed to work pretty well. On level roads with outside temperatures of 85 – 95 degrees, elevation 3,000’ – 4,000’, AC on, 60 mph, the transmission ran between 185 – 195 degrees. It pulled 6% grades at 50 mph, 3rd gear, air temp 70 degrees with a transmission temperature of 200 degrees. On an 8% grade starting at 5,000’, 95 degrees outside temperature, I tried pulling at 45 mph but the transmission went to 210 degrees and the engine temperature went from the normal 210 to 225 degrees so I quickly shut off the AC, shifted down, and backed down to 35 mph and the temperatures dropped back to normal within about 3 miles. This was the only time on trip that engine temperature went above 210. I tried to keep in the ‘towing mode’ but this can be a challenge as it resets each time the engine is shut off, too bad the electronic wizards at GM can’t figure a way to sense when a trailer is hooked up to the rear connector and automatically switch to the ‘tow mode’. I also tried to keep the ‘anti skid’ feature off as I am not sure how it would interact with the inertial trailer brake controller in an emergency.

My 2007 Tahoe has the 5.3L engine, 4L60E transmission, 3.73 rear end, and is 2 WD. The overall gas mileage on the trip was about 11 mpg, long term average 15 mpg, and it gets 19 – 20 mpg freeway empty.

I am satisfied with the Tahoe as a tow vehicle, it is unfortunate that GM doesn’t provide an auxiliary cooler and factory brake controller given the transmission has a towing mode and the vehicle comes with a receiver rated for 10,000 lbs.

 

I went on a 60 mile run pulling a 8000 lb boat with my suburban and the trans temp was only around 189-195 most of th eride except for a steep 3 mile hill on the interstate that I had to climb. I climbed the hill at 65 mph and the trans temp only went to 201 degrees and dropped back down to 190 as soon as I crested the hill. Over all, I would save that's not bad?

 

There is a 4.10 axle which is more favorable to towing...also has transmission cooler

 

201 degrees sounds OK, wonder what the outside temperature was? Probably want to keep transmission below 225 degrees. I have several steep grades to deal with on I5,
Siskiyou pass and Grape Vine through San Berdino mountains so want to get as much margin as possible.

 

Reply to Gixer: The 4.10 rear end would be better for towing but the only GM auxillary transmission cooler I could find for 2007 vehicles was for the Silverado pick up series. The dealer story I got was there were aux coolers for 2006 Tahoes but none for 2007.

 

It was in the 80's the day I towed the boat.