Noticable noise in front end at high speed

[SnookMan]

Ok Explorer gurus....I need a diagnosis! All of a sudden I have a loud humming noise in my front end at 55mph....after that it goes away till I hit about 67mph where it gets louder, then at 75 or so its gone. I feel it in the floor board under my feet. The best discription would be the resonance you get from an aftermarket exhaust system at certain RPM's. Took it to the dealer, let them drive it around, and they said I had a bad REAR wheel bearing. I knew that, and the sound was totally different than what I hear up front. They replaced the rear, but the front is STILL making the noise. Can the wheel bearing go bad yet not have the noticable wear signs such as play etc? Is there any other way to diagnos the bearing to determine if that is the culprit? The delaer just seemed to like driving my truck, all the mechanics came out asking what all I had under the hood, commenting on how great it sounded, and didn't really offer answers. Tires are fairly new, need to fix this its driving me nuts!

 

[Mathematics]

I had 3 out of the 4 (2 front, 1 rear) wheel hub assemblies go bad & get replaced on my mounty between 100-115k miles, replaced the 4th for good measure. They seem to go bad at about the same time. Not too hard to do yourself, there's a good how-to on this site as well.

 

[HiImBrian]

Have your wheel and steering alignment checked. Some shops will check it for free for you.
And yes, your bearing can be bad without showing signs of play...