Carbon buildup on the top of the piston is common. As the buildup increases with mileage and over time, symptoms vary from light ticking, to ticking/hammering, to hammering/knocking noises. Fuel injector cleaner often solves the problem.
Average mileage: 106,169 (90,000–122,339)
Engine affected: 3.3L V6
11 people reported this problem