Wheel bearing vs rear differential noise???

[uponone789]

I have an '04 XLT 4.6 4x4. I have a constant light whine from 35-60 mph...when I release the throttle between that speed the noise goes away, re-apply the throttle and the noise returns. I like the vehicle and I'm prepared to spend some money on maintenance but I would like to find a way to isolate this noise.
Thoughts???

Thanks!

 

[94Eddie]

It sounds like a classic case of rear differential gear whine to me. It is a fairly common occurrence on third gen Explorers and Mountaineers. Bad bearings usually have more of a grinding sound.

 

[uponone789]

The vehicle has 87k miles and is in great shape...should I just resign myself to the fact that this noise exists or pay to have it fixed? Obviously a subjective question I know but I'm kinda shooting in the dark here.

 

[94Eddie]

Differential whine typically doesn't require a repair. They can run for years that way. I had it on a Mountaineer and decided to get it taken care of rather than live with the noise. It is not a cheap fix. Expect to pay a shop $400-$600 in labor and another $800-$1,000 for a rebuilt differential. The good news is it doesn't have to be done. If it is/was bearings then things would be different.

You might lessen the noise with a change of gear oil. I recommend going with a synthetic oil.

 

[swetrid]

Ring and pinion problem when noise goes away when you let off throttle.

 

[uponone789]

I recently changed the rear diff fluid per my search here...no luck. Thanks for humoring me.

 

[akdoggie]

The whine you hear while running under load, then letting off and getting no noise, is either a bad differential front pinion bearing or the infamous gear wear whine. Either require parts replacement to relieve the noise.

Personally, until this differential starts the howling stage, I wouldn't spend the money on the repair. If your pinon seal is leaking, I'd pull the rear flange, remove the seal and check the pinion bearing. If you need to change the seal, a couple minutes more wouldn't hurt to check it out. You'd be surprised how often that it is the culprit, not the gears. It's worth the look if the seal if leaking. Good luck

 

[uponone789]

Thanks for the info....I keep the vehicle in my garage at home and there are no leaks anywhere.