Wheel Bearings Diagnosis (Tapered): Etching

The bearing surfaces appear gray or grayish black in color, with related etching away of material usually at roller spacing. See Fig 1 .

1. Check the seals.
2. Check for proper lubrication.
3. Clean all of the parts and the housings.
4. Replace the bearings. Refer to WHEEL HUB, BEARINGS & SEAL.

Fig 1: Identifying Etching

Courtesy of GENERAL MOTORS CORP.