Most modern engines today are overhead cam engines, which require a long belt or sometimes a chain to drive the camshaft. The belt or chain runs from the crankshaft to the camshaft located above the cylinder head. Many times the belt or chain runs the water pump also to save space and having to run any extra belt. Timing chains require little maintenance and wear very well. Timing belts are used in the place of chains by some manufacturers. If you don’t periodically inspect your timing belt, it might break at an inopportune moment.
Many cars have interference engines, or motor wreckers, as many mechanics refer to them. If a timing belt breaks in an interference engine, the valves may open at the wrong time and then be struck by the pistons. The result will be many hundreds of dollars in damage to your engine. If you don’t have an interference engine, a broken timing belt will leave you stranded — which is inconvenient — but won’t do any permanent damage.
Not sure if you have an interference engine? You can check here.