Timing chain issues in Ford 3.5L engines, particularly in models like the Ford Taurus, Explorer, and Edge, can lead to poor engine performance and costly repairs. Common problems include chain wear, slack, or tensioner failure, which can cause rattling noises, engine misfires, or even catastrophic engine failure if left unaddressed. Regular maintenance and timely inspection of the timing chain system are crucial to avoid these issues. Signs of a failing timing chain include engine noise at startup, rough idling, or poor acceleration. Replacing the timing chain and associated components early can prevent significant damage to the engine.