Interference engine models produced by parent company Chrysler and used in some Dodge automobiles include the 2-liter engine used in the Dodge Neon from 1994 to 1998 and the 2.5-liter V-6 used in the Avenger from 1995 to 1998. Pentastar engines produced since 2010 are also interference engines.
The term interference engine refers to any engine where part of one or more of the engine valves extends into the same space as the piston in the engine cylinder. The valves are normally retracted out of the way of the cylinder during the compression cycle to avoid damage. While interference engines are potentially more efficient than noninterference engines, there is a high risk of serious damage from the piston striking the valves in an interference engine at high speed if a timing belt or chain failure occurs. A failure of this kind often causes enough damage to render the engine a total loss.
Many older Chrysler and Dodge interference engine designs use a timing belt, but the newer Pentastar V-6 engine design uses a timing chain. A major reason for this change is the increased durability of timing chains. While timing belts must be replaced periodically due to wear, most timing chains last the lifetime of the engine. Chains are also tougher than timing belts, reducing the overall chance of catastrophic damage from a timing chain failure.