This component is one of the essential and consumable parts of 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 part can cause serious engine damage, timing belt breakage, and ultimately bent valves.
Roller failure at low usage may be caused by dust or water entering the timing belt cover, or engine oil leaking into the cover. The first sign of roller failure is noise in cold weather. It is recommended to purchase complete timing kit products for proper replacement.