Noticeable vibrations and noises can be a sign that the belts that attach the Balance Shafts to the Crankshaft are worn. Rough idling when stopped at a red light or a loud rumbling are telltale signs of a damaged Engine Balance Shaft Chain. This can also be caused by excessive metal wear or leaky oil seals. The issue is common in 4-cylinder engines and can lead to performance hiccups from low oil pressure and bad timing in Camshaft Parts.