A timing chain, or belt, is an integral part of an automobile's engine that controls the opening and closing of the valves in the engine. If the chain breaks, serious damage to the engine could result. Proper maintenance is important to prevent this from happening.
A timing chain can break with either too much or not enough tension. If the chain does not have enough tension, it can develop slack. This can result in the chain "slapping," leading to premature fatigue. A chain with too much tension can also fail, as it is placed under excessive stress. Tension increases friction and heat in the chain, which can result in failure.
Engine seizure can be caused by an engine overheating or running out of oil, causing pistons to seize inside the cylinders. If an engine seizes while running at high speeds, the sudden stop can cause a timing chain to break.
The age and number of miles driven on a timing chain are major contributors to failure. The more miles you have on your vehicle, the higher the odds your timing chain will fail, as the chain will become weak and break. Most car manufacturers suggest you have the chain replaced every 60,000 miles.