Have had the truck for a year and last weekend was the first real time I used the truck to tow. The air temp was about 85 degrees. For almost the whole trip the fan clutch was engaged. Running at 70 mph and fan locked in. After a couple miles fan unloads. As soon as you go down a hill and let off the throttle the fan clutch engages and and takes a while to unload. Trans temp never went over 200 & engine temp never made it to 210.

I took it to the dealer today and of course they could not find a problem with it. They said this is normal.

This is my second Duramax and did not have this problem before. Anyone else have a problem like this or an idea how to get the dealer to replace it, short of having to hook up the trailer & make the service adviser take a ride out of town.

go to the dieselplace.com and do a search for lly overheating there is a ton of stuff on there about this problem and yes chevy does know about it

Thanks, on first page found a thread with the problem.