Drove my wife and Mom down to tour a plantation this afternoon - about 35 miles each way, all freeway. Truck has 2400 miles on it. For the first time ever, I noticed a noise that sounded to me like a large electric fan of some sort (sounded like the Flex-A-Lite fan on my brothers Jeep) that came on intermittently. This happened at 75mph, cruise on, level, steady speed and RPM, no road surface changes or anything. It would come on for between 5 and 15 seconds, then go away again. Also, sounded like it spooled up and down - not just an on/off. It probably happened 5 or 6 times each way.

I'm hoping there's a fan I'm unaware of that could be doing this - any thoughts? I'm confident it's NOT:
~ Turbo whine
~ Tire noise
~ Wind noise

Other than that, I'm open to ideas. Thanks.

 

the only thing I can think of would be the radiator fan. but mine rarely kicks on unless I'm towing slowly uphill, or in heavy traffic going slow and it's hot.

I know from the past the fan clutch on these trucks have been prone to go bad and actualy break in the engaged possition. you have the fan, but with a radiator as large as this you dont need it when moving.

 

interesting....I have approx 90 miles on my new '06 3500. I am a senior'ish seasoned truck driver with approx 1.5 million miles on my own class 8 Cummins powered big-rig...and both my wife and I could swear we heard something similar...not as long in duration maybe 3 seconds...or so two or three times at aprox 70 moh after an extended throttle press...woooooppps!...( to help in the break-in procedure)....maybe my mind is NOT playing tricks on me.....tell me more

 

Well - glad it's not just me at least! Still, I'm no closer to having an answer. I haven't heard it again, but I haven't been back out on the freeway either. One of these days, I'll start reading through the service manual - there's probably a clue in there - but I have yet to have that much uncommitted free time. Keep in touch if you find anything out, and I'll do the same - hope you're enjoying your new truck as much as I am!

 

I'll keep an eye out at some of my other haunts and see if I see anything there about this.