Right Rear wheel bearing?

[Motorhead440]

2008 Explorer Limited 4.6 130k miles, . No accidents. Second family owner. I'm hunting down a very loud low pitched howl/whine that occurs between 55-65 mph. Seems to emanate from the left front or possibly right rear and becomes much more pronounced with even the slightest amount of left steering input and goes away completely with right steering input.
Troubleshooting to date with no change in symptom at all:
Replaced both front wheel hubs
Replaced tires (nice set of Michelins)
Four wheel alignment
Removed front driveshaft and test drove it

I'm now thinking power steering pump or rack or maybe right rear wheel bearing? Troubleshooting ideas welcomed? I'm starting to consider strapping a GoPro to various parts.

Thanks Everyone !

 

[Explorer_PL]

Lift the rear, spin the tires and listen with a stethoscope. I have replaced several of them on our 06 with 310 k miles. And I also thought the sound was coming from the front. Sometimes you can wiggle and feel the play but not always.

 

[Trainmaster]

The wheel bearings in these trucks have a reputation for going bad ... But you say you replaced the front ones already? Hard to tell which one it is. Sometimes they don't make noise when they're off the ground. I wound up doing both after choosing the wrong one.

If you do decide the replace the front bearings, there's a good tool available for beating the old ones out. They rust in place and really don't like to come out. Trust me.

 

[Bill MacLeod]

Agree with PL, use a mechanic's stethoscope. If you have either 4x4 or awd, get all 4 wheels off the ground then engage cruise control and probe each wheel bearing around the knuckle and close to the bearing. A noisy bearing will be quickly heard.

Do this in a safe manner, vehicle properly supported and stay clear of all rotating parts and hot exhaust.