Been pumping money into the truck, but still chasing a (new) noise. Just had an Auburn installed in the rear ('03 4x4 Hemi QC) and I replaced the left front hub assembly as it was sounding bad. Also did a brake job all the way around. But I have a new noise to keep me up at night. When I hit almost exactly 38 mph I get a whiring, moaning sound from what seems to be the right front. It picks up speed with the truck and I can hear it up to just about 50 or so, maybe it's still there but the wind noise, etc, covers it up. It doesn't seem to matter if I am accelerating or deaccelerating, and when I slow down to stop I can hear it until about 10 mph or so. I can't tell if turning makes a difference yet as it isn't very loud to begin with. In fact my wife said "you're worried about that noise?" since it's so low. My gut tells me it gets quieter when I turn, but I'm not sure. I crawled all around under her tonight and everything looks ship-shape, tight, no movement that I wouldn't expect, no slop, no leaks, tore boots, anything. The infeed shaft into the front diff turns a little, less than 1/8th of a rev before it engages something, and the front shafts only turn a tick. The only thing I noticed was that the diff was a hair low, so I topped it off. And I do mean only a little low, 1/2" too low at most. The new front bearing is a Timken, for what that's worth, and I did get a front alignment as I replaced the upper control arm and tie-rod end as well (don't ask! ).

Sorry it's long, but any ideas? I'm afraid I have a front diff bearing going, but I guess it could be the U-joint. Is it possible the new bearing will just make noise for a little bit (I've only put 60-70 miles on it so far) or is that wishful thinking? (I'm afraid I know the answer...). I am planning to tow a 24' TT this weekend, so I'd like to at least know what I'm dealing with.

THANKS!!!!

 

Could be the differential pinion bearing or depth and gears making the whining noise.

 

Unless the noise gets louder when you turn right or left, I doubt that is a wheel bearing unless its in it's early stages?? You could jack up the front and wiggle the front wheels in/out on top and bottom. I'd lock the steering wheel first to prevent side-side movement.
The new bearing shouldn't make any noise unless it's defective. i think what we got going on here is the same as lots of guys...You were just picking on your truck for noises and found one??? happens to alot of guys.
QAs far as the front diff being low. pretty sure they are suppose to be filled 9/16"-1/2" below the fill hole so maybe you weren't even low?
At any rate, the front pinion bearing does get the most wear but it barely has pressure on it when in 2wd. The turning of the driveshafts...completely normal. There has to be some backlash movement or there would be bind so it's typical for the shafts to move slightly before the pinion comes into complete contact with the ring gear.
*If the noise is apparent then maybe there is some wear inside the housing somewhere. Hard to be completely certain unless taken apart, but if it's not barely noticeable, and there's not much glitter going on in your diff oil. I'd drive it like it is unless it bothers you or begins to get louder..

 

I have EXACTLY the same issue with my 06 Hemi QC, same whining noise at the same speed. If you find out where it come from please let me know wera. Thanks :-)