This manual covers the Mitsubishi S6S / S6S-T Diesel Engine, a robust power unit engineered for reliable performance in demanding industrial applications. Specifically designed for forklift trucks, including models FD35-FD50, FD60, FD70, FD70E, FD40K, FD40KL, FD45K, and FD50K, these diesel engines are built with Mitsubishi's commitment to quality and durability. Their efficient design and strong engineering ensure consistent operation, making them a trusted choice for material handling equipment. The purpose of this original factory illustrated service repair manual is to provide comprehensive guidance for the maintenance, repair, and technical understanding of the Mitsubishi S6S / S6S-T Diesel Engine. It includes detailed information on general procedures, maintenance standards, special tools, overhaul instructions, and testing and adjusting protocols. Furthermore, it covers the proper servicing of various engine systems, including air inlet and exhaust, lubrication, cooling, fuel, and electrical systems, along with specific instructions for alternator types and glow plug inspection, ensuring optimal performance and longevity.