This manual covers the Komatsu 12V140-1 Series Diesel Engine, a powerful V12, 14.0 L, water-cooled engine featuring direct injection, and turbocharged and aftercooled aspiration. It is designed for robust performance and reliability in demanding applications, serving as a critical component in various heavy-duty equipment including models like the SA12V140-1, D475A series, WA800 series, and HD785 series. The engineering quality of this engine ensures sustained operation and efficiency, making it a trusted choice for industrial and heavy machinery needs. This comprehensive Service Repair Workshop Manual provides essential information for the maintenance and repair of the Komatsu 12V140-1 Series Diesel Engine. It details general information, engine structure and function, testing and adjusting procedures, disassembly and assembly guidelines, and maintenance standards. With step-by-step instructions, detailed illustrations, and exploded views, this manual is an indispensable resource for servicemen, do-it-yourself enthusiasts, and experienced mechanics. It also includes crucial hydraulic and electric circuit diagrams, along with troubleshooting charts to aid in diagnosing and resolving issues efficiently.