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Serpentine Belt Replacement

What is a serpentine belt?

The engine in your car has many roles to fill. It has to do more than move. It also has to generate electricity, assist with power steering, cool off the passengers, and keep itself cool. The serpentine belt - sometimes referred to as the fan belt, alternator belt, or accessory drive belt - is used to spin, or "drive," several components attached to the engine. It drives the alternator that powers the electrical system and recharges the battery. It also drives the power steering pump, the air conditioning compressor, and the water pump. (The water pump circulates coolant through the cooling system). In the past, multiple drive belts were used to turn pulleys attached to these components. Today, most vehicles employ just a single belt - the serpentine belt - to do the job.

How does the serpentine belt work?

As the engine's crankshaft pulley turns it drives the serpentine belt. In turn, the belt drives the pulleys for the other systems including the air conditioning, alternator, water pump, cooling fan, and power steering.

High-quality serpentine belts are less likely to squeak and/or prematurely fail.

What are the symptoms related to a bad serpentine belt?

Over time serpentine belts stretch, crack, and the ribs that ride on the accessory pulleys being to wear smooth. A squealing noise that increases with engine speed or as engine driven accessories are turned on may be noted. The noise is caused by the belt slipping on the pulleys, insufficiently driving them. Ineffective air conditioning, a battery warning light, or intermittent power steering assist can result from this. »MORE: Symptoms of a bad serpentine belt

Can I drive with a serpentine belt problem?

A slipping belt means one or all of the accessories are not being driven properly. Loss of air conditioning, electrical power, power steering, or water pump and fan drive are possible depending on the severity of the wear. If left for too long the belt can shred or come off of the pulleys. The belt should be inspected as soon as is convenient to protect against becoming stranded.

How often do serpentine belts need to be replaced?

Replacement intervals vary by vehicle and driving conditions. We typically see this part replaced approximately every 100,000 miles.

How are serpentine belt issues diagnosed?

The technician will visually inspect the serpentine belt for wear or fluid contamination. The belts have grooves that locate them laterally on the accessory pulleys. These will be checked for cracking or chunking. On vehicles equipped with automatic belt tensioners there is usually a gauge on the tensioner that indicates how much the belt has stretched, this will also be checked.

How is a serpentine belt replaced?

The technician will loosen the tensioner to allow slack in the belt. After removing the old belt, the technician will route the new one over the accessories, then release the tensioner so that it puts tension on the belt. The vehicle will then be started to check that the belt has been properly routed.

Over time, serpentine belts crack, become glazed, and can squeak or even break. For optimal performance and reliability, they should be replaced at the recommended interval by the manufacturer.

We recommend replacing serpentine belts if related components are being repaired and the belts have signs of wear or have over 30,000 miles on them.

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