Interference engines made by Ford include its 1.6-liter single overhead cam engine, 2.0-liter double overhead cam engine, 2.2-liter engine, 3.0-liter single overhead cam engine and 3.3-liter engine. Ford's interference diesel engines include 2.0-liter, 2.3-liter and 2.4-liter units. The 4.6-liter engines in the 1991 to 1998 Crown Victoria cars are interference engines. Ford used its 2.0-liter engine in the 1993 to 1998 Probe, its 2.2-liter engine in the 1985 Ranger truck, and its 2.0-liter engine in the 1986 to 1988 Ranger.
If a timing belt breaks in an interference engine while the engine is running, the pistons and valves may collide, because they do not have enough clearance between them if the cam stops turning. Engine failure results, which means thousands of dollars worth of internal damage. In a non-interference engine, the pistons and valves have more space, and no collision occurs if the timing belt breaks while the cam is moving.
Owners of Ford vehicles equipped with interference engines and timing belts rather than timing chains should follow the automaker's recommendations for changing timing belts. The replacement interval recommendation is 60,000 miles for most vehicles built before 1995, the year automakers began using longer-lasting ethylene propylene diene monomer synthetic rubber in their vehicles' timing belts. Ford cars equipped with interference engines and timing belts include the 1993 to 1998 Ford Probe and 1991 to 1998 Crown Victoria.