This manual covers the Komatsu 12V140E-3, a V-type, 12-cylinder, water-cooled diesel engine designed for heavy equipment applications. Known for its robust engineering and reliability, this engine is built to perform under demanding conditions. Its powerful design ensures efficient operation and longevity, making it a dependable component in various industrial and construction settings. The purpose of this Full Service Repair Manual is to provide comprehensive guidance for the maintenance and repair of the Komatsu 12V140E-3 engine. It details essential procedures, technical specifications, and troubleshooting information necessary for owners, mechanics, and technicians. By following the instructions within this manual, users can ensure optimal performance, safety, and extended service life for their equipment.