Volvo advises that a new timing belt be inspected and adjusted, if necessary, at 600-1200 miles (966-1932 km). The timing belt should be replaced at 50,000 miles (80,000 km). Replacing the timing belt before its recommended interval is a wise choice. It is far less expensive to replace the belt than to repair the engine damage which can result from the belt breaking.
Inspect the belt for cracks, missing teeth and wear on any of the surfaces. Inspect the sprockets for grease and other deposits. If any of these conditions exist, the belt should be replaced. Please refer to Engine & Engine Overhaul for procedures on timing belt removal and installation.