Decoupler Pulley Archives - UnderhoodService
Engineering Better Belt Systems

An accessory drive belt is always both speeding up and slowing down.

Replacing a Decoupler Pulley (VIDEO)

Millions of vehicles have decoupler pulleys, heres how to replace them. This video is sponsored by Litens.

Advanced Belt Noise Diagnostics

One of the noisiest components under the hood of a vehicle can be the belt and the drive components. Noise is not the fault of the belt, but the result of how the power comes from the crankshaft and the components attached to the belt.

10 Tips For Serpentine Belt System Inspection And Service

The serpentine belt is part of a system and is not the only component susceptible to wear. The tensioner, idler pulley and, on some vehicles, the decoupler pulley all wear over time and need periodic inspection and replacement. If you are replacing just the belt without looking at the other components, you could be sending a new belt to a premature death.

VIDEO: The Best (And Worst) Ways To Install A Decoupler Pulley

Andrew Markel discusses several installation and removal processes for decoupler pulleys, including which will produce the most reliable results. Sponsored by Litens.

VIDEO: Idle Quality On Kia Vehicles

Andrew Markel discusses a recent TSB about idle quality on the Kia Sorento, and how the problem was solved at the alternator level. Sponsored by Litens.

VIDEO: Steering Vibration Or Moan On Honda Vehicles

Andrew Markel discusses steering noise, and the repair necessary to correct the noise and vibration conditions. Sponsored by Litens.

Servicing Decoupler Pulleys

Alternator pulleys are not so simple anymore. Many late-model vehicles are equipped with special pulleys that are engineered to reduce NVH (noise, vibration and harshness) and extend the life of the alternator. An Overrunning Alternator Pulley (OAP) has a one-way clutch mechanism inside the hub that allows the belt to turn the alternator in one direction, but allows the alternator to “free wheel” and spin at its own speed when the engine suddenly decelerates.