2003 2wd quad, 6sp, dually. Strange noise to describe. At idle, ac off, at times a very slight "whine". After a stop, whine or roar will gradually get louder. Upon letting off the fuel pulling up to a stop, the whine will be same volume as the truck slows down, then before coming to a complete stop, the whine will quit. It sounds liking "spooling down". Same thing if I kick it out of gear at say, 50mph. Sometimes when making a very slight left or right, like on to an exit ramp the noise usually will go away until straightening out to continue on another road. I did notice the other day when towing our fiver, at exactly 66 mph the noise completely goes away. A little more fuel or less fuel and the noise is there. It doesn't really seem like a tire but at this point I'm totally confussed!

 

Do your boost levels correspond with your noise?

 

I had a similar noise in my 09 6.7, it ended up being a very slightly cracked exhaust manifold, it eventually cracked all the way and made the usual clacking exhaust leak sound but it started out as a high pitched whine....

 

The "roar" continued and last week the ABS and Brake light came on, showed right front wheel bearing. Replaced the hub and fixed it up. Lights out and "roar" gone.