i have a 2006 impreza that has a noise coming out of the rear of the car. it sounds like a wheel bearing and only does it when its cold,could it be the wheel bearings or something in the rear diff? the car has awd and four wheel disc brakes.

soopsoop,

 

Typically wheel bearing noises can be narrowed down by driving at moderate speeds and swerving the car from left to right and back again. Listen for changes in the volume, pitch, and the actual sound, as the inside and the outside bearing races are loaded up and then released from the car's weight. If the pitches, etc. change from one swerve to the next, you've most likely got a wheel bearing going bad.

 

The best way to know for sure is to get the car in the air, with the wheels spinning in 2nd gear (2000 rpm) and use a stethoscope to listen to the individual bearings and the center differential.