Οverrunning alternator pulley: common defects and their signs

1. Wear-out or corrosion of mechanism elements
   • Short specific cracks are heard in the engine compartment at starting or turning off the power unit.
   • Vibration is noticeable, especially at low speeds.
   • Greasing stains appear on the pulley protective cap.
2. Jamming
   • Vibration and whistling of the belt as well as tensioner clicks are noticeable.
   • Alternator drive belt starts slipping and can break.
   • Car’s electric equipment may fail.

How to replace an overrunning alternator pulley?

Unlike the clutch itself which has a specified service life, the alternator clutch pulley on the car is replaced if necessary. This component is solid and can’t be repaired.

The procedure of overrunning alternator pulley replacement requires professional equipment and skills. Demounting of the part can cause significant difficulties because of too small distance between the alternator and the car body and due to excessively tightened component fasteners. That is why replacement should be entrusted to service station professionals. Often it requires removing the alternator, and in some cases - the wheel as well. Sometimes access to the alternator is blocked by other components, for example by the power steering tank; they also should be removed. It will be necessary to demount the drive belt and disconnect the battery negative terminal.

You can disconnect the pulley with a special tool only. For installation of a new component you will also need a torque wrench. This will allow to observe tightening torque for fasteners which is specified in the car manual.