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Locked Alternator?

Published by Chad Carnahan on Mar 31st 2016

When installing alternators, you will often remove the pulley from an old alternator to reuse it on the new replacement unit.   When attaching the pulley to the new unit, the rotor will sometimes slide down a little. The distance of this movement is generally no more than 1/8-1/4 Inch. However, it makes a big difference.

When the pulley is tightened on the new alternator, it must be tightened enough to pull the rotor back up in place. If the rotor is not pulled up, it will not engage. The alternator will then appear to lock up with no rotation.

If this happens, go through the process of attaching the pulley again. Be sure that the rotor is fully in place. Then your alternator will function well.