What is the recommended action if a timing chain has excessive deflection?

If a timing chain has excessive deflection, the recommended action is to replace it. Excessive deflection often indicates that the timing chain has stretched or worn to the point where it can no longer function properly. A timing chain's main purpose is to synchronize the rotation of the crankshaft and camshaft, ensuring that the engine's valves open and close at the correct times. If the chain is too loose due to excessive deflection, it can lead to incorrect timing, which may cause significant engine performance issues, misfires, or even catastrophic engine failure.

Replacing the timing chain ensures that the engine operates within the manufacturer’s specifications, maintaining optimal performance and preventing further damage to other engine components. While adjusting the tensioner can temporarily alleviate some issues with chain slack, it does not address the root cause of chain wear and would not be a long-term solution. Lubrication, while essential for the health and operation of engine components, does not resolve the issues caused by excessive deflection in the timing chain itself. Leaving the timing chain as it is would risk severe damage to the engine, making prompt replacement the most appropriate action.