Overrunning Alternator Pulley System

Creating more efficient parts within a vehicle takes a combination of ingenuity, perseverance, testing, and “KNOW HOW”. Because vehicle systems such as self-parking assist, rear bumper cameras, vehicle performance diagnostics, other electrical systems and crash avoidance systems are getting more and more complex – they require a constant supply of energy to run effectively. Energy to power these systems, the engine, and many other vehicle applications come from the car battery, but must be powered through the conversion of electrical energy from the battery - through the alternator. In order to create that much needed flow of electricity, your vehicle depends on the dedicated work of the serpentine belt, which “snakes around” and spins the alternator. Until recently, the alternator was always spinning while the engine was running but now some newer model vehicles come with overrunning pulleys – which assist the alternator in continuing to produce energy – allowing it to “coast” when the engine is decelerating.

There are many benefits to this. Overrunning pulleys are able to disconnect from the alternator allowing it to be at rest occasionally which means that the alternator will last longer. Overrunning alternator pulleys also provide additional vibration isolation for smoother engine performance, greater fuel efficiency and longer serpentine belt life – because “even your Serpentine Belt can use a break!” Overrunning pulleys also help save money because if they need to be replaced due to use, then it’s likely that the alternator is still good. This is because the pulleys taking on much of the stress in maintaining power – not the alternator itself. Keep in mind, the alternator will still be checked, but replacing a pulley is a much more affordable option than replacing an alternator.

This type of alternator system is quickly becoming standard in most new model vehicles because of the increase fuel economy and reduced wear it provides.

Don’t forget, NAPA AutoCare technicians are here to help you with all of your starting and charging issues and can diagnose any of these systems in your vehicle.

Posted January 28th, 2016