I have a 2001 Ford F-350 crew 4x4 that is making a loud whistle noise. I thought it was the brakes at first but had them checked out. They said it was coming from the rear end. It is loud enough to turn heads while driving. The noise stops at about 10 mph. It sort of sounds like air coming out of a balloon with the opening stretched tight. Loud and shrill. Any ideas before I have to take it into the dealer?

 

Have you ever had the center carrier replaced? Someone here, less than a year ago, complained about this. I posted this TSB which is what it ended up fixing his problem. Even though it doesn't include your truck, you could still have a defective carrier bearing. It's worth a shot :

Article No. 03-22-2
NOISE - DRIVESHAFT CENTER BEARING NOISE - VEHICLES BUILT AFTER 6/1/2002
DRIVESHAFT - DRIVESHAFT CENTER BEARING NOISE - VEHICLES BUILT AFTER 6/1/2002

Publication Date: October 17, 2003

FORD: 2002-2003 F SUPER DUTY


ISSUE:
Some 2002-2003 Super Duty F-Series vehicles built after 06/01/2002, with a multi-piece driveshaft may exhibit a squeaking and/or squealing noise from the center bearing while driving. This noise is produced when the bearing seal rotates in the bearing outer race.

ACTION:
To service, replace the center bearing. Use a center bearing assembly with a white paint dot (built after 6/9/2003). Determine the style of the driveshaft per (Figure 1) and (Figure 2), then follow the appropriate Service Procedure below.

SERVICE PROCEDURE
NOTE: WHENEVER DRIVESHAFT REMOVAL IS NECESSARY, IT IS IMPORTANT TO PAINT MARK THE DRIVESHAFT TO THE TRANSMISSION (OR TRANSFER CASE) AND THE REAR AXLE. ADDITIONALLY, MARK A PAINT LINE THE ENTIRE LENGTH OF THE MULTI-PIECE DRIVESHAFT ASSEMBLY. THIS IS ESSENTIAL TO INSURE THE DRIVESHAFTS ARE REASSEMBLED IN THE SAME ORIENTATION AS ORIGINAL. FAILURE TO REASSEMBLE THE DRIVESHAFT IN ITS ORIGINAL ORIENTATION MAY RESULT IN AN UNBALANCED DRIVESHAFT CONDITION.
F81Z-4800-FA
F81Z-4819-AA
E4Hz-4A254-B
F81Z-4N272-AA.

You could try spraying (soaking) it with WD-40 to see if the noise disappears. looks like this (if you've never heard of it) :

 

I have had the same thing in the past on my '01. It hasn't happened in awhile. It seemed to happen when I parked it in the salt air for a few hours. I never figured out what it was, but come to think of it, it hasn't happened since I put on new brakes.

 

Good call n578md, thats exactly what the prob is. The carrier bearing. And its covered under my warranty. Thanks......Bob