Crank Pulley Problems

Written by andrea stein | 13/05/2017
Crank Pulley Problems
Crank pulleys drive numerous car parts, but they can develop problems. (Vintage Car Engine image by itsallgood from

A crankshaft pulley refers to the main pulley that attaches to the front of the crankshaft, which is used to drive such parts as the alternator and air pump. Crank pulleys can develop problems that can affect how these and other parts of a vehicle operate.


Crank pulleys can warp due to loose or improper installation. This can result in faulty crank pulley operation as well as causing wear on the belt used to drive the pulley. Suspected warping can be checked by removing the crank pulley and placing it on a flat surface. If warped, the crank pulley should be replaced and all other parts involved should be checked for physical damage.

Lack of Spin

A malfunctioning crank pulley may not spin while the engine is in motion. This lack of spin often means that the crank pulley is not properly attached to the crankshaft, which can result if the small metal key used to lock the crankshaft and crank pulley together is broken or lost. If the pulley has not sustained damage, a replacement key can be installed to correct the issue.

Harmonic Dampener

Aftermarket crank pulleys are often sold without harmonic dampeners, which absorb vertical and torsional vibrations from the crank. A crank pulley lacking a dampener absorbs excess vibrations, which can lead to pulley failure.

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