Noise...while moving

Looking for help/suggestions.

2000 Yukon XL 4x4.

While moving forward, above 5mph, our Yukon has developed a "noise." It's a cyclical, rotational noise that speeds and slows with the speed of the vehicle. As for the tone of the noise, it sounds like a jet flying overhead. I actually had a co-worker listen for it and he said he thought it WAS a jet flying overhead (I work 5 miles from an airport). But please don't think it's as loud as a jet, it's not THAT extreme. As the driver, the sound seems to come from under and/or just forward of me. However, I have had people comment on hearing it in the middle row.

I have checked all brakes including the e-brake, replaced front rotors and pads (they needed it), bled the brakes, and changed front differential and transfer case fluids. Tomorrow I will have the tires rotated and balanced, but I would be really surprised if that proved to be the cause (it's too loud at too low of speed for road/tire noise, I think).

I'm trying to do cheap/easy stuff first (that needs done anyway) before I take it in to have it looked at. Any suggestions or help you can offer is appreciated.

Hi,
is it the same whether it is in Auto 4WD, 2Hi, 4Hi?
Accelerating, coasting, decelerating?
Left turn, straight, right turn?
Drivetrain stuff makes me nervous, so I vote for having an experienced mechanic listen to it. He may just say, yes, this is XYZ, heard it ten times before.
I certainly do not have a clue.
Take care, Eggert :bananasmi

To me (driver)...it appears to stay on all the conditions you mention above. However, last night, passengers in the rear said they thought it went away upon medium to heavy acceleration. When I took it in to have tires rotated/balanced yesterday, their mechanic thought it might be something with the rear differential, but it's not their expertise. Rear passengers think the noise comes from the rear, so my perception of the noise eminating from the under me could be wrong.
BTW...last night (highway trip) I think I felt "something" when my foot was flat on the floor board and traveling at a very slow speed (idle...traffic jam). It seemed to happen at the loudest point in whatever noise I'm hearing.

Hello, I have a 1996 GMC Yukon and I started noticing the noise too I took it to the mechanic and when they put it in reverse it made the noise even worse and they told me it was the transmission althought I think they may be wrong I will be getting a second opinion.

Well...the Yukon went in for an official look today. Service guy just called to say they found an "enormous amount" of metal contamination in the inner and outer rear bearings. They are currently checking for axle damage and the cause. I'm already gearing up for the sticker shock.
Anyone experience this or the cost to fix?

Bearing is the culprit. According to the service guy it contaminated a bunch of other stuff so he reccomends replacing bearings, seals, and other stuff. +$1,200 worth. I'm sure some of it is a "might as well replace it while we have it apart" type thing. So, since it's our tow vehicle...

I have a 1999 GMC Youkon - we first noticed the noise about 2 weeks ago and its getting worse. Is this something a good mechanic can fix or do I need to take it to a rear end shop? We are taking a trip in a month and I have to have it fixed!!

Hi Virginia, it depends on how good the good mechanic and his shop and equipment is.
You know that the dealer will fix it right in a short time, although probably not at the lowest price.
Ask the dealer, the good mechanic and the rear end shop for an estimate, have them explain what they will do, and why. Then decide on what you feel most comfortable with.
Take care, Eggert :bananasmi