The Mercedes-Benz 300 D Turbo, part of the W123 generation produced from 1976 to 1985, represents a pinnacle of mid-size luxury sedan and wagon engineering. Renowned for its legendary diesel reliability, exceptional fuel economy, and solid construction, this model offered a comfortable ride and timeless design that set it apart from contemporaries like the BMW 5 Series Diesel and Audi 100 Diesel. Powered by robust inline-5 cylinder diesel engines (OM617 and OM617 A turbocharged) and inline-4 diesel engines (OM615), the 300 D Turbo is celebrated for its enduring appeal and the exceptional longevity of its powertrain when properly maintained.

This comprehensive service manual provides detailed repair, service, and maintenance information for Mercedes-Benz W123 300 D Turbo models, covering engine variants OM615, OM617, OM617 A, and M115. It encompasses all major systems, including the powertrain, chassis and suspension, electrical and electronics, and body and interior. Within its extensive pages, you will find step-by-step repair procedures, routine maintenance schedules, troubleshooting guides, diagnostic capabilities, rebuild specifications, and detailed wiring diagrams. This manual is an indispensable resource for enthusiasts, DIY mechanics, and professional technicians seeking to maintain and repair these iconic vehicles.