Low humming noise with slight vibration
 

I own a 2004 F250 6.0 4X4 with 80,000 miles on it. No mods, and I have owned it since it was new. My problem is that I have an annoying hum that sounds like it is coming from the front end. The noise is only there when i am cruising down the road and seems to get loader as i go faster. I have never done any work to the front axles or hubs, It does have 35" tires and a leveling kit. Some suggestions from talking with other people are: unit bearings?, locking hubs? , and u-joints. How can I narrow this down so that i am not spending money buying and replacing parts that I dont need? Also, this noise just started about 2 weeks ago. Any suggestions?
Thank you

Do you have the auto-lock hubs? Are they in the lock position or the auto position? This is going to be a tough one...

Can you describe it a little more?

Auto locking hubs. they are in "auto" position. I engaged the 4wd but it did not change the noise at all. I sounds like a bad bearing, but there is also a pinging noise at very low speeds. At first i thought the noise was engine related, but it only occurs at road speeds. there is no power loss or any thing like that. The turbo does make a new noise when i shut the engine down you can hear it spinning to a stop well after the engine is shut down. But i dont think that is related?

Have you done / checked the front brakes?

is it possible that a small pebble got stuck in the pads and is just grinding away?

When you drive down the road swerve back and forth and see if the noise changes any. if the noise goes away or lessens when you swerve on way or the other then the bearing is bad on whichever side you're swerving twards because you're taking the weight off that side causing the noise to change. :c:

another thing to check is the bearing in the AC compressor, mine just went bad with 253k on it, could hear a wirrring sound, no belt squeal until it froze up at idle, the bearing was totally gone, had to be this way for a while to look like this did. just loosen the belt and check it out.