Over time, the rubber used in belts can wear down, eventually leading to cracks and breaks. Alignment problems with the belt and other issues within the engine can cause problems as well.
Although car belts are durable, they're subject to regular movement every time the car operates. In addition, the engine compartment heats up, which can damage the belt as well. Belts don't always fail catastrophically; parts of the belt can peel or flake off, and the belt might squeal if its position slips. Belts should be examined annually and replaced periodically to avoid a breakdown, advises Firestone Complete Auto Care.