Whining when under power

[freema22]

I have a 2004 Tahoe with AWD. Since new, there has always been a slight whine from the front end. Now, with 142k, the whine seems to have gotten louder. I changed the diff and trans fluids and they looked and smelled fine. There doesn't seem to be any loss in mpg. If I shift into neutral, the sound goes away. The tone of the sound changes with speed, and seems the loudest around 45mph.

Any ideas?

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[ccapehartusarmyINF.(ret)]

is it in 4WD or Auto

 

[freema22]

I have AWD, so the only switch is 4LO. It's definitely not that.

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[FrankU]

Here you go. This was the fix for me.

http://www.tahoeyukonforum.com/forum/showthread.php?t=29948

 

[freema22]

The symptoms don't match what I'm describing. I don't have any issues with my brakes or power steering. I wish the solution was as simple as a system flush.

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[clandr1]

I've heard the front differentials on AWD trucks need to be rebuilt every 100k or so. Perhaps the whine is the front diff on its way out.

 

[TheAutumnWind]

I have a similar whine. Its not loud, but it is there. I have flushed the hydroboost system already. Trans and diffs are next on the list.