Timing belt and chain replacement is one service that isn't going away any time soon. Most Ford engines with overhead cam timing belts have a recommended replacement interval of 60,000 miles to 120,000 miles depending on the application (see the chart on page 54). So if a customer is driving a vehicle that is more than 5 or 6 years old, he may be driving on borrowed time if the timing belt has not been replaced. The risk of belt failure goes up sharply once a belt surpasses its recommended replacement interval, which for most Ford applications (except the Taurus SHO) is 60,000 miles. The recommended replacement interval for the timing belt in the 3.0L and 3.2L V6 Taurus SHO is 100,000 miles and 120,000 miles for Focus.

The consequences of a timing belt failure on a Ford depend on the application. Fortunately for many Ford owners, there is enough clearance between the valves and the pistons so no harm will come to the engine if the belt snaps. But on older Escorts (up to 1985) with 1.6L engines as well as 1989 and up Probes with 2.0L or 2.2L four cylinder engines, a timing belt failure will usually bend a bunch of valves. The same goes for the Mazda-built 3.0L V6 in the Mercury Villager. On the older cars, the cost to repair the damage may be more than the vehicle is worth - which means your customer has to make a painful decision either way.

The main thing to keep in mind about timing belts is that belt failures oft...