Fig. 12: Identifying Heat Discoloration
Courtesy of GENERAL MOTORS CORP.
Heat discoloration ranges from faint yellow to dark blue. This discoloration results from overload
or an incorrect lubricant. Excessive heat causes softening of the races or the rollers. In order to
inspect for loss of temper on the races and the rollers, perform a file test. A file drawn over a
tempered part will grab and cut the metal. A file drawn over a hard part will glide readily with
no metal cutting. Replace the bearings if overheating damage is indicated. The tempered part will
fail the file test. Inspect the seals and the other related parts.
Misalignment
2007 Hummer H3
2007 Driveline/Axle Front Drive Axle - H3