This manual covers the Komatsu SAA6D125E-5 engine, a robust inline six-cylinder power unit designed for demanding applications. With a displacement of 12.5 liters, this water-cooled engine features direct injection and a forced lubrication system, engineered for reliability and performance. Its substantial bore and stroke contribute to its efficient operation and durability, making it a cornerstone for various Komatsu 125E-5 series equipment. The purpose of this comprehensive workshop manual is to provide detailed technical information and guidance for the maintenance and repair of the SAA6D125E-5 engine. It includes essential procedures, specifications, and troubleshooting steps necessary for owners, mechanics, and technicians to ensure optimal performance and longevity. The manual covers critical aspects of engine upkeep, including filter replacement intervals, and serves as an indispensable resource for all service-related activities.