Going too long between oil changes and using the wrong type or viscosity rated motor oil causes the timing chain pins and plates to wear, resulting in timing chain stretch. In almost all cases, timing chains stretch due to improper owner maintenance. When a timing chain wears or the timing chain guides are damaged, metallic particles may be found in the drain oil. Those misfires and excessive emissions can then result in costly damage to the vehicle’s catalytic converter. In other words, valves that don’t open and close exactly when expected cause an incomplete burn, resulting in a reduced power contribution from each cylinder and excessive emissions. When the intake and exhaust valves are out of time with the crankshaft, they cause incomplete combustion that’s detected by the engine control computer and reported as a misfire. At idle speed, the result is a rough idle that causes the engine to shake when you’re at a stop. Since the timing chain controls when the intake and exhaust valves open in relation to the pistons, a worn chain can cause the valves to be out of time, opening and closing slightly early or late. However, if the timing chain wear is great enough so that the tensioner can no longer compensate for the slack, the noise may continue even after warm up. If the engine is equipped with a hydraulic timing chain tensioner, the noise may disappear or lessen as the engine oil warms up and the tensioner removes some of the slack. The excess slack can cause a rattling sound or even a clanking sound if the slack is severe enough to cause the chain to slap against the timing chain cover. Timing chain noise is most noticeable on cold startup when oil pressure and flow is at its lowest. Stretching, in turn, causes other problems. When an owner neglects oil changes or uses the wrong oil, the timing chain pins wear, causing the chain to stretch. New and stretched timing chain Timing chain problems
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