The OM617 is a five cylinder diesel engine used initially in the w115 models in 1974. Considered by many as one the most reliable engines ever produced.

Hugely successful in the USA the engine was the main reason behind the success of the Mercedes W123.The first  incarnation was a 80hp unit later an 87hp was introduced. Used in various models including the S class and G wagons the engine also found its way into the 209,309, & 409D Vans.