Fan clutch problems

sandrat · July 1, 2003

I have an 02 2500HD 8.1/Allison 4.10 and it seems like the fan comes on way too often. It's around 103 degrees here in arizona and it will run almost all the time when towing 11,000 lbs down the level interstate. Even at 95 deg and no load it comes on everytime I pull off the interstate and slow down or stop. I don't remember it running this often when it was new. Now have 30,000.

Do these fan clutches go bad often. Is there a way to test it? Coolant is full in radiator and overflow tank no belts slipping, etc.

ugeesta · July 6, 2003

I also have the same question. We just got back from a 1000 mile trip across the continental divide and had fan clutch issues. We were driving empty in 100 degree heat with the A/C running. When we got into town, the fan would engage at every stop light. This became rather annoying after a while and were wondering if this is a warrenty issue. Our truck is a 2002 GMC 8.1 w/Allison with 2100 miles. We ended up shutting off the A/C to help the motor (which it did). Shouldn't this truck be able to run in high temps. without a load and not have to run the fan?

Another item of notice was the grade brakes on the Allison Transmission. It worked great coming down the mountain, but almost too good. The transmission would go into lower gear to slow down, but would slow us down too much. I had to accellerate to downshift the transmission so we didn't stop. Is there any way to kill the grade brake system when you have slowed down enough?

One more item and then I'll stop. We noticed that the engine compartment was making funny noises in the heat. I think it was coolant siphoning into the overflow reservior, but am not sure. The noise seemed to be coming from the coolant reservior side of the engine compartment. Any ideas?