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Inspecting and Replacing Accessory Belts

Keeping the bands together is practically a cinch

Even though the names may suggest otherwise, serpentine, and v-belts have little to do with Grandpa's plaid Sansabelt golf slacks. Grandpa may, however, have a serpentine or v-belt under the hood of his Buick. He may even have a spare belt in the trunk along with his golf clubs. The automobile engine, you see, not only provides the power to keep the Buick going down the road and get Grandpa out to the links, but also provides power to what are collectively known as engine driven accessories. The air conditioner compressor, the alternator, the power steering pump, the water pump, and some even more exotic devices such as a supercharger, are all driven by a system of pulleys and a belts.

Power Player

The power player in this game of pulleys and belts is the engine. Connected to the engine crankshaft is the Big Kahuna of pulleys. All the other pulleys are driven from this one pulley, with a belt or belts running through it all to keep things spinning. Older vehicles sometimes had multiple V-belts to drive all the accessories involved. The V in this case refers to the shape of the pulley valley in which the belt sits. Imagine a little v stuffed into the valley of a big V and the picture becomes clear. Later model vehicles did away with the V-belt system in favor of a single serpentine belt. A serpentine belt earns its name from its ability to turn and twist around corners, like a snake.

Belt Tightening Measures

As with any moving part, accessory belts eventually wear out. This is true regardless of belt type—serpentine or V-belt variety. When an accessory drive belt fails, so does the function of the accessory. A water pump that stops pumping will cause the engine to overheat. An alternator that stops spinning will stop making electricity and charging the battery. An air conditioning compressor that stops compressing will bring hot air blowing out of the previously cooling interior vents.

While a serpentine belt adds singular simplicity to driving accessories, all will stop working if the one belt fails. While some redundancy was built into the older multiple V-belt systems, the one belt that did fail was usually the one that left you walking along the side of the road after the engine overheated or the battery drained. For these reasons inspecting and replacing the accessory drive belt according to the recommended service intervals is a capitol idea. Even though modern accessory belts can last up to four years, the only way to determine condition to is take a good look at the pulley-driven side of the belt. A quick twist of the accessory belt with the battery disconnected and the engine cool is one way to inspect belt condition. The best way to do this is to remove the belt and flex it slightly against its natural curve. Replace the belt if it shows glazing, cracking, fraying or wear any kind.