Making a humming noise?

[rockabilly29]

I am new to this site and have a question that maybe you guys had the same trouble. I have '98 sport with 108,000 miles. Just recently, it's been making a humming noise as I drive but winds down when you brake. Almost like if I had oversized tires on it. Also does it when i throw it in neutral as i drive. Brakes, rotors are new and cv joints and ball joints look good. No tears in boots or damage to it. front u joint replaced about 2 years ago. Any suggestions? I thought it would be cv or ball joints ( which were never replaced )? Thanks

 

[Blee1099]

Is it humming or does it sound like a train whistle? If its sounds like a train whistle, then you should try cleaning your IAC.

 

[rockabilly29]

Is it humming or does it sound like a train whistle? If its sounds like a train whistle, then you should try cleaning your IAC.

Nope, it's definite a humming noise like if i had oversized tires

 

[isuballr]

I have sort of the same problem, but it only occurs around 30 mph and comes from the rear of the vehicle. I just had my tires rotated a few days ago, and i never heard it before then.

 

[Turdle]

Sounds like my friends problem, so Im linking these together
http://www.explorerforum.com/forums/showthread.php?p=1507525#post1507525

 

[Skibug]

Cupping tires is a common problem with our trucks. If you have any type of aggressive AT tread, the tires will cup when the alignment is out of wack just slightly or due to worn ball joints etc... I would first try rotating the front tires to the rear and see if the noise changes location, pitch, etc... If the noise changes, then it's your tires cupping. Mine are cupped and it sounds like I've got mudders on the X.

 

[isuballr]

Hmm...i'll have to check that out. Since I did just get a rotation 4 days ago that could be the problem. Thanks.