Pinion Bearing Noise
WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
Pinion bearing failures can be distinguished because pinion bearings rotate at a higher rate of speed than the differential side bearings or drive axles. Rough or excessively worn pinion bearings produce a continuous low pitched whirring or scraping noise on low speed acceleration from a stop.