by Jody L. Campbell
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Replacing a pulley bearing in 90 percent of alternators is a fairly benign task, the hardest part is usually removing the alternator. Some vehicles have the alternator on top of the engine and are therefore relatively easy to remove. On other models, the alternator is at the bottom of the pulley system for the drive belt, in which case you must lift the vehicle. A Haynes repair manual for your specific vehicle will guide you through the alternator removal process. In many applications, replacing the pulley will require removal of the alternator.
Place a suitable size 1/2-inch drive impact socket into the alternator pulley bearing retaining nut.
Test the gun to make sure it is turning counterclockwise.
Place the gun anvil in the socket square.
Use a pair of padlocks to keep the pulley bearing stationary.
Remove the bearing from the pulley.
Insert the new pulley bearing into the alternator. Replace the pulley bearing retaining washer and nut. Screw in the nut by hand.
Tighten the nut with the impact gun, but do not overtighten it. Tighten the pulley bearing retaining nut to the correct torque specifications for the specific alternator you are working on.
- Make sure your replacement is the same size and type of pulley bearing as the diferente. Altering the size of the pulleys can cause the relationship between the crank and the pulley bearing to become out of sync, generating too much or not enough alternator power.
- Make sure the alternator does not require a free pulley from the alternator decoupler (OAD). If so, replace it with one. Many newer vehicles use OAD pulleys due to their superior performance than a conventional pulley. Replacing a regular pulley on an alternator that uses an OAD pulley can cause severe drive belt vibrations and damage other pulleys.
Articles will need
- 1/2 Inch Pneumatic Impact Gun
- Impact socket set with 1/2-inch drive
- Channel locks
- Replacement pulley bearing
- Torque Specifications for Pulley Bearing
- Torque wrench