Rear end Humming/Mechanical noise.

[BipolarXpress]

Bought this truck a year ago and have had many issues. Recently had a rear end sound so I took it to a shop. They diagnosed it as rear axle bearings. They replaced those and now the noise is back.

Whats been done so far.

-All bearings front and rear changed
-Brand new EGR Valve (Rough idled and sometimes died at stop lights) Fixed that problem
-New O2 Sensor

Sure enough 2 weeks after getting it back the noise was there again. Got a feeling the dealership got the diagnosis wrong. I think personally its something with the differential. Anyone ever have this issue?
The sound almost seems to be coming from right below the rear passenger seats. Maybe the front of the bed. I know its not the bearings at this point.

 

[Karlsweg]

Pinion and case bearings changed too?

 

[BipolarXpress]

No but that may be the next thing done. I'll take it in in the AM. The differential doesn't seem to be loose or anything. At least not yet. Any noise that isn't natural drives me nuts. I have new tires but I don't think they'd cause that much noise.

 

[BipolarXpress]

Could it possibly be tire noise from misalignment?

 

[Karlsweg]

Yes. What tires are you running? If they are all terrain, they could be humming:

 

[Karlsweg]

I had to rebuild my rear after it started whining. The 9.25 has tiny pinion bearings that fail. I replaced all wheel, pinion and carrier bearings. (And races) The gear oil was full of bearing material. But I had noticeable slop when moving the yoke back and forth.

 

[BipolarXpress]

I think I have some pathfinder all terrain.

 

[Redtruck-VA]

You could jack the wheels off the ground and run it up a little to see if there is noise. Check differential fluid for metal debris.