2nd Gen Non-Engine/Transmission Intermittent Fan type blower/ humming sounds heard while towing

[GBrock]

While towing my 13,000 lb boat last weekend, if I was going up a hill at WOT, I would occasionally hear a type of blower or fan running sound... almost like a radiator fan kicking on for maybe 10 to 30 sec then cutting out. What was that? I drive a 99 2500. Was it indeed my radiator fan kicking in? Wouldn't it be running all the time while towing under heavy load anyway?

 

[RustyJC]

It was the thermal fan clutch turning the engine-driven cooling fan on and off. Perfectly normal. About the only time I hear mine is towing up a long hill. Next time you hear it, watch the water temperature gauge - it will drop about 10 degF and the fan will shut off.



Rusty