I purchased my duramax a few months ago. I pull a 28' gooseneck horse trailer. My fan clutch started sticking while pulling the trailer 70 miles at 75 mph. I took it to the dealer they said all was fine, but didn't seem to confident in their answers I had asked them about my truck. I can understand the fan clutch engaging at idle but not going down the highway. Now the fan clutch will engage with or without a trailer behind my truck. Any info would be greatly appreciated.

Same problem with mine.


Mine will do it running 80-85 unloaded up and down the hills at a mild outside temp of 85 degrees. Towed this weekend and it would engage around 70-75 for a few minutes then release. I was only towing about 5k.


IRRC my lb7 did the same thing until I got the Juice. My new LLY juice is suppose to be here tonight so I will let you know if it makes any difference.


My dealer said it was normal as well.

Mine just started doing the same thing the other day. Funny thing is I only notice mine in the mornings before it gets warm. I have not called the dealer yet, I thought it might have been me just hearing things b/c the truck had been parked for a few days but low and behold every time I start the truck up cold it sounds like a big wind machine until it gets warmed up some. By the way the truck has 1300 miles on it.

this is strange. the first lly I test drove did it on warm up only. I did the 24 hour test drive and i was totally annoyed by it. when my truck arrived I was thankful that I was not hearing it but now when I tow it is totally annoying. all I am towing is a 4500lb ski boat. it is pretty warm here 85-95 but the guages say everything is really cool and it still turns on. I thought it was normal. sure is annoying

More talk here about this

http://dieselplace.com/forum/forum_posts.asp?TID=11507&PN=1

Its not actually a clutch but a fluid coupling (silicone bath). Depending on the design parameters it will lock the fan to the pulley at certain temperatures - this is normal. Could be than GM wanted to make sure to have good cooling under all circumstances and overengineered it a little bit. I am driving an Avalanche with the 327 CID engine and somethimes the fan comes on when there is no real explanation for it (crusing at 55 miles per hour, no load) - it unlocks with higher speeds. Temp here was around 85 - 90 degrees.