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.

What happens when a timing chain breaks while driving?

A broken timing chain will cause an engine to not start or fail while driving. If the belt is already broken, the engine won't have enough compression to start. If it breaks or jumps while driving, the pistons will be damaged from contact with the valves. The valves themselves will bend and potentially ruin the engine.

Is it common for a timing chain to break?

The timing chain in an internal combustion engine connects the crankshaft and camshaft. ... An internal combustion engine will not run with a broken timing chain or belt. Timing chains are rarely known to break during an engine's typical lifetime.