The term serpentine belt may conjure up images of a snake like object. That representation is actually pretty accurate. The serpentine belt is a long, winding belt that connects many of your vehicle’s components, including the power steering pump, alternator, and air conditioning compressor, and more, to the vehicle’s crankshaft pulley. In some engines, the serpentine belt also runs the water pump, radiator fan, and supercharger.

Years ago, most engines had several V-type belts. Each belt was responsible for running one or two accessory components. This was often an inconvenience because instead of having one belt to maintain, there were several belts that had to be maintained and replaced.

Today, most vehicles have one ribbed serpentine belt responsible for running all of the accessory components. This belt can be tensioned automatically or manually. Automatically tensioned serpentine belts are the most common and are kept at the proper tension with a tensioner comprised of a housing unit, spring, idler pulley with bearing, pivot, and mounting bolts. The automatic tensioner is designed to apply constant accurate tension to the belt. Manually tensioned serpentine belts are less common and have a mechanical adjustment comprised of threaded bolts, nuts, and adjustable slotted brackets.

Serpentine belts are made of high quality reinforced rubber. The lifespan of the serpentine belt depends mostly on the material it is made of. Older Neoprene rubber belts generally last about 50,000 miles, while newer belts made from Ethylene Propylene Diene Monomer (EPDM) rubber will last up to 100,000 miles.

Serpentine belts can fail in a few different ways. The most serious failure is when the serpentine belt breaks completely. This is usually the result of a belt in poor condition, or a problem with one of the accessory components being driven by the belt. A failed bearing in a pulley being driven by the serpentine belt will also cause the belt to break.

Some possible consequences of a serpentine belt breaking while driving include: the illumination of warning lights on your dashboard, difficulty steering the vehicle, engine overheating, and the battery going dead in a few miles because the alternator would not be charging. A broken serpentine belt will have numerous negative effects on your engine and can potentially be dangerous.

There are many indicators that your serpentine belt may need to be replaced. Deep cracking in the ribs and spine of the serpentine belt is a common indicator your belt is due to be replaced. A noisy belt is also indicative of a problem. Your serpentine belt can also become contaminated with oil or coolant due to other issues with the vehicle. These contaminants will reduce the life of the belt and contribute to irregular noises.

An aged belt may become shiny or glazed in appearance. It may also begin to harden and lose some of its flexibility. An aged belt made of EPDM rubber may also show excessive wear in the ribs and valleys of the belt which can lead to slippage. An EPDM belt will not crack like traditional Neoprene rubber belts. Instead, it will wear and lose rubber similar to the way a tire wears out. EPDM belts need to have the rib valleys inspected with a belt wear gauge. All of these potential issues can be easily detected during a routine inspection.

Take the time to have a trusted automotive technician inspect your serpentine belt, belt tensioner, and the accessory components driven by your serpentine belt every time you take your vehicle in for routine services. Serpentine belts typically give ample visual warning of impending failure. Driving your vehicle with an old and worn out belt is a disaster waiting to happen. Drive with peace of mind by having your serpentine belt inspected and replaced when necessary.