Your car’s alternator is what delivers energy to your vehicle’s battery. It works by means of converting mechanical energy to electrical energy, taking power from the engine’s crankshaft and delivering it to the battery where it is stored. The alternator connects to the crankshaft by means of a belt – either a V-belt, or a serpentine belt. With a V-belt, only the alternator is driven. If your vehicle has a serpentine belt, then other components are also powered. If the alternator belt breaks, then the car battery does not receive a charge, and accessories may not operate properly, if they work at all.

The alternator belt is constantly working, from the time you start your vehicle until the time you turn it off. Like all other automotive belts, it is made of rubber, and that means that over time, it can deteriorate. Usually, you can expect your alternator belt to last 3-4 years. You should have it inspected regularly – a good rule of thumb is to have your mechanic check the alternator belt whenever you have an oil change.

Signs that your alternator belt needs to be replaced include:

  • Fraying, cracking or looseness
  • Headlights and/or interior lights flickering or dimming
  • Engine will not turn over
  • Car stalls
  • Accessories do not work

If you notice signs of wear on your alternator belt, or you experience any of the symptoms noted above, you should have a qualified mechanic check the belt. Have the mechanic replace the failing alternator belt to eliminate any further problems with your vehicle.

This article originally appeared on YourMechanic.com as How Long Does an Alternator Belt Last? and was authored by Valerie Johnston.


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