Hi,

My 180,000 mile '04 XC90 2.5T AWD has a significantly noisy whine in the front end. Seems to originate around the driver footwell. It becomes audible from about 40mph to about 80mph, above which it seems to cease. This only manifests under acceleration and the pitch becomes higher as a function of increased speed, NOT RPM. Noise immediately goes away on deceleration. No issues with engine or transmission (that I know of) and it runs fine otherwise.

Can I rule out wheel bearing noise since it stops when I take my foot off the gas?
Can I rule out transmission b/c it's not linked to RPM?
Could it be a transfer case or differential issue?
CV joint noise (no cracked boots)?

It's loud and annoying, so any ideas?

Thanks!

 

It sounds like the drive gears in the transfer case. It is not the end of the world, but the gears are not sold separately.

Have it checked on a lift with a mechanic's stethoscope and source a good used part.