SWPDX

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.

07summitwhite

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?

GIXXER

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

SWPDX

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.

SWPDX

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.

07summitwhite

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