[LarryJoe50]

I have a 2007 SR5, 4.7 with tow package. My issue is today for the 1st time my trans temp gauge red lined. I just went up a incline of two mile at 7% grade and was home. I was backing up my trailer (which has a dry weight of 5600 lbs. and Gross weight of 7600 lbs. But I never travel with fluids in my trailer so I would be well below the max weight for towing. I have towed this trailer over mountains and no issue. Just had my truck's cooling system flushed and replaced at the dealership. Outside temp was around 74 degrees. I ran my transmission in "S" mode at 4th gear and it kept kicking up and down the different gears. Related? I don't know. Could this just be a fluke? I feel that the truck can more than handle this tow job.

 

[LarryJoe50]

Admin: you may move this to proper forum if needed. thx

 

[RinconVTR]

Just had my truck's cooling system flushed and replaced at the dealership. .

That's likly you're problem, depending how the "flush" vs "replacement" was performed. I do not know if you have the tow package with the 4.7L and/or ATF cooler either.

May be the 5.7L system is different, I honestly have no idea. But I'll tell ya, I just got back from a 3 week trip out west towing a 7k TT with my Sequoia in the hottest parts of the country and then even towing up the tightest, highest mountain roads in the Southwest of which a 32' trailer can travel. Multiple days of 115-121 degree heat while towing all day long. The hardest day was the Death Valley switch backs entering the West side when temps were nearing the high for day of 121 and then all the way Eastward thru Furnace Creek and Amargosa Valley. Trans and Coolant gauges never budged. Torque app registered a high coolant temp of 212, but was not working for actual ATF temps.

 

[LarryJoe50]

Thanks for the info, yes my truck is equipped with a tow package and I was wondering about the service myself. I have to take it back in to have them replace the lower cooling hose. (could you believe that did not have a coolant hose and had to order it from Texas, I live in Oregon). I will have them take a look at it.