The contact owns a 2013 Mercedes-Benz C300. The contact stated that upon starting the vehicle, there was an abnormal rattling sound coming from the engine compartment. There were no warning lights illuminated. The vehicle was taken to a local dealer where it was diagnosed, and the contact was informed that the timing chain tensioners were faulty and needed to be replaced. The vehicle was not repaired. The contact had experienced the failure with the timing chain tensioner on three separate occasions. The manufacturer was notified of the failure. The approximate failure mileage was 60,000.