This component is one of the important and consumable parts in a car engine. It consists of a bearing and a plastic roller on which the timing belt runs. It is usually replaced during timing belt service or replacement. Failure of this component can cause serious engine damage, leading to timing belt breakage and ultimately bent valves.
Early roller failure may result from the entry of dust or water, or from engine oil leaking into the timing belt cover. The first sign of roller failure is usually noise, especially in cold weather. It is recommended to purchase the complete timing belt kit for replacement.