The OAP040 Overrunning Alternator Pulley has an outside diameter of 50mm and width of 35.8mm. The inside diameter of the mounting hole is 17mm and the pulley suits a 6PK belt. Please confirm dimensions match before ordering as some variation may exist based on year, engine code, and configuration.

With the ever increasing number of accessories and auxiliary systems that require extra electrical power in modern cars, Overrunning Alternator Pulleys (OAP) are becoming increasingly popular on many late model vehicles to deal with increased alternator loads and engine torsional fluctuations. 

Auxilliary systems such as power seats, heated and cooled seats, GPS navigation systems, electric power steering systems, on board entertainment systems and more all place increased strain on alternators, front end accessory drives and drive belts, unless managed effectively by quality overrunning alternator pulleys.

Dayco OAPs allow the alternator to ‘freewheel’ when the belt speed drops and are engineered with one-way clutches that allows the rotational inertia of the alternator to “overrun” during any belt deceleration. Dayco OAPs, which are designed for long service life, decrease drive belt vibration and reduce belt slippage during rapid acceleration or deceleration, resulting in reduced stress on the drive belt and other accessories as well as increased alternator and drive belt life.

Note: Overrunning alternator pulleys require special tools for removal and fitment.

Suitable for the following applications. Please confirm details before ordering:

• Mercedes Benz|C220 CDI|Sep 2004 - Jun 2007|2.1L 4 cyl DOHC 16V CRD Turbo Diesel W203|Eng code: OM646.963|OAP (Alt Bosch, 200A)
• Mercedes Benz|E270 CDI|Aug 2002 - Aug 2005|2.7L 5 cyl SOHC 20V TCDI Turbo Diesel W211|Eng code: OM647.961|OAP (Alt Bosch, 200A)
• Mercedes Benz|E320 CDI|2003 - 2005|3.2L 6 cyl DOHC 24V CRD Diesel W211|Eng code: OM648.961|OAP (Alt Bosch, 200A)