Worn Timing Chain Symptoms

by Quinn MarshallUpdated June 06, 2023
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All vehicles are equipped with either a timing belt or a timing chain. While a timing belt is made of fiberglass-reinforced rubber, a timing chain is made of metal and looks similar to the type of chain used for bicycles. The timing chain is turned by the crankshaft and is responsible for operating the camshaft. If a worn timing chain is not detected before it breaks, the resulting engine damage could cost thousands of dollars to repair.

Rough Idle

When a timing chain is worn, it develops slack and becomes loose. When this happens, the engine’s valves, which are powered indirectly by the timing chain, will no longer run correctly. When the valves begin to run off-sync, the engine will function poorly and cause the vehicle to have a rough idle. A rough idle usually involves shuddering or shaking while the vehicle is in park or the brakes are applied.

No Ignition

If a worn timing chain becomes so loose that it no longer sits correctly on the gears and doesn’t turn properly when the crankshaft is engaged, the engine will not turn on. When this happens, it is important to replace the chain before attempting to start the vehicle. If the vehicle starts with a severely worn or broken timing chain, the engine may suffer costly or even irreparable damage.

Poor Function

A worn timing chain will allow the valves to operate at incorrect times, which causes the engine to run very poorly. When the engine runs poorly while driven due to a worn timing chain, the symptoms may include backfiring, bucking, shaking and sputtering.


When a timing chain is worn, it becomes loose. Because it is loose, it may cause a rattling sound from near the engine when the car is running. This is due to the loose chain vibrating when spinning from the crankshaft. This is a sign that the timing chain is near the breaking point and should be replaced promptly.

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