A typical serpentine belt with tensioner: The serpentine belt is a long belt that snakes its way through a series
of pulleys, idlers, and a belt tensioner. This design eliminates the need for multiple drive belts. An effective
cost-cutting design, serpentine belts tend to last much longer than traditional V-belts, usually upward of
50,000 miles.
Timing Belts
Timing belts are the Rodney Dangerfield of all the belts in your car. They don’t
get no respect. Many of today’s cars are equipped with a timing belt in place of
the old timing chain. The function of this small yet critical member is to keep
your engine mechanically “in time.” In a four-stroke internal combustion engine
(intake, compression, power, exhaust) the top half of the engine must be
synchronized with the bottom half to complete the four-stroke cycle. The timing
belt achieves this synchronization by meshing with cogs connected to the
crankshaft and camshaft, ultimately producing power in your engine.
The timing belt is made out of rubber and is subject to wear and tear from
mechanical and environmental conditions. The environment of the engine is
quite hostile. The under-hood temperatures can exceed 500 degrees. Corrosive
fluids such as oil, hydraulic fluids, and battery acid are present, and there are
mechanical hazards in the form of metal and hard plastics.