Download The information relating to timing belt replacement intervals is additional to the main purpose of this CD, but is included to provide guidance to garages and for customer advice. Where possible the recommended intervals have been compiled from vehicle manufacturers’ information. In a few instances recommendation has been made by the manufacturer and the decision to replace the belt must be made from the evidence of a thorough examination of the condition of the existing belt. Apart from the visible condition of the belt, which is explained fully later in this section, there are several other factors which must be considered when checking a timing belt: 1. Is the belt an original or a replacement. 2. When was the belt last replaced and was it at the correct mileage. 3. Is the service history of the vehicle known. 4. Has the vehicle been operated under arduous conditions which might warrant a shorter replacement interval. 5. Is the general condition of other components in the camshaft drive, such as the tensioner, pulleys, and other ancillary components driven by the timing belt, typically the water pump, sound enough to ensure that the life of the replacement belt will not be affected.