No more than 1 mm of pulley rock should be visible.
Alternator One-way Clutch Pulley Inspection
CAUTION:
Be careful not to damage the rotor.
NOTE:
The following steps can be done while the alternator is installed on the vehicle if the drive belt is removed and the alternator electrical connectors are disconnected.
1. Secure the rotor using a medium size screwdriver and a rolled shop towel.
2. Turn the pulley clockwise when viewed from the front.
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Pulley should be locked.
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If it rotates in both directions, replace the alternator.
3. Turn the pulley counterclockwise when viewed from the front.
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Pulley should turn with some dragging
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If it locks or has unusual resistance, replace the alternator.