Mid range whining/harmonic noise
 

I know it's impossible to describe a noise coming from a truck- looking to see if anyone has some insight. I have a noise at idle only- started during cold starts and now just when idling and in gear. It sounds like a pulley bearing or something. Not sure if this has anything to do with it but I was sitting in parking lot the other day and turned a/c on- after a few moments I thought my truck was on fire. Looked like smoke from under my hood. I jumped out and smelt freon. I shut her down, turned off air and restarted. All was good - I ran air again- no issues and still blowing cold. I'm boggled and annoyed at this new noise! I have a video but don't know how to attach it!

Well found out the hard way it was a pulley bearing. Truck threw the serpentine belt going down the road, no power steering, no brakes, no fun!!!!! I should have know since my truck didn't chirp at shut down :stupidme:

just curious......what do you mean by "chirp at shutdown" ?

Usually the 5.9 will make a squeak when the truck is shut off. Like the belt squealing- There is an aftermarket pully that can be put on the alternator to prevent this if it annoys you.

thanks for your reply that's exactly what my truck is doing and while it's annoying my main concern was "what's going on"...kind of sounded like the belt or possibly a bad bearing so when I read this post I had to chime in

Very likely that an idler pulley bearing is crapping out. Loosen the surp belt, remove from idlers and spin away. You'll know right away if the idler bearings are crap.