Mercedes-Benz OM617 Engine Specs

The Mercedes-Benz OM617 is a naturally aspirated inline-five diesel engine produced from 1974 to 1991, one of the most legendarily durable diesel engines ever built and a major reason for Mercedes-Benz's enduring reputation for near-indestructible diesel power. It was used in the W123 (as the 240D and 300D), the W126 S-Class (as the 300SD), and the early W460 G-Class, vehicles that remain in active daily service in various parts of the world even decades after production ended.

Producing between 75 and 125hp and 181-240Nm of torque from 2,998cc, the OM617 uses a comparatively simple SOHC 10-valve head and an extraordinarily high 21.0:1 compression ratio, reflecting the mechanically simple, purely mechanical (non-electronic) fuel injection system typical of diesel engines from this era. Mercedes rated the OM617 for an astonishing 500,000km-plus service life, and it is genuinely common to find these engines running well past 800,000 or even 1,000,000km in taxi and commercial service across parts of Africa, the Middle East, and Eastern Europe, where they remain prized specifically for their mechanical simplicity and tolerance of poor fuel quality.

Because the OM617 uses purely mechanical fuel injection with no engine control computer whatsoever, it is remarkably simple to diagnose and repair even in locations with minimal technical infrastructure - a major reason for its continued popularity in demanding markets decades after Mercedes stopped producing it. Common maintenance items include periodic injector pump and injector servicing, glow plug replacement for reliable cold starting, and general age-related wear appropriate to an engine that is now, at minimum, well over three decades old in any surviving example. Timing chain condition should be checked on any high-mileage example, and given the OM617's near-mythical reputation, any well-documented example represents one of the lowest-risk classic diesel purchases available anywhere in this database. The main practical consideration for most buyers today is less about the engine's own durability and more about the condition of the surrounding vehicle, since decades-old bodywork, interior components, and electrics have usually seen far more wear than the engine itself.