This manual covers the Komatsu 12V140E-3 engine, a robust V12, turbocharged, water-cooled unit with a displacement of 13.96 liters. Known for its engineering quality and reliability, this engine is designed for demanding applications, delivering approximately 370-420 horsepower. Its direct injection fuel system and precise bore and stroke dimensions contribute to its performance and efficiency. This Workshop Service Manual provides comprehensive guidance for professional technicians. It details essential maintenance procedures, including lubrication and filter replacement, along with troubleshooting steps and technical specifications. The manual's purpose is to ensure the optimal performance, longevity, and safe operation of the Komatsu 12V140E-3 engine through accurate repair and maintenance practices.