I had it happen 2 different times. A belt makes a much different sound than the sound I believe he is describing. One time it was the egr thats bolted on with 2 bolts on the back top of efi intake, it was loose, and whislting loud as hell. The other time, it was a rod bearing, and it sounded very high pitched, not really ear hurting loud like the air leak, but a annoying sound that was a very high frequency.
Coul also be pulleys or belts, but those made a way dif sound than my air leak and bearing did.
