Lower Timing Chain Tensioner that is responsible for maintaining the correct tension on the Timing Chain that connects the Crankshaft and the Balance Shaft. It is recommended to replace this Tensioner when Replacing the Timing Chain and Guide Rails. While Timing Chains are designed to last a lifetime, it is possible for them to stretch and possible for the tensioners to fail. We recommend inspecting these components to prevent severe engine damage, especially on high mileage vehicles (over 150K).