This manual covers the Yanmar Marine Service Repair Workshop Manual, designed for the service and repair of Yanmar marine engines and related systems. It provides comprehensive guidance for models including the 1GM10, 2GM20(F), and 3GM30(F), along with marine gear models Km2p, Kmp3, and Km3v. Engineered by well-qualified technicians, this manual reflects high quality and is utilized across industries, offering a reliable resource for maintaining these marine powerplants. The scope of this manual is extensive, serving as a complete guide covering all aspects from front to back. It details engine systems such as the basic engine, fuel system, governor, intake and exhaust, lubrication, and both direct sea-water and fresh water cooling systems, including modifications. Transmission systems, remote control, and electrical systems are also thoroughly addressed. With easy-to-understand Simple English and clear illustrations, this workshop manual is an invaluable learning resource for aspiring mechanics and essential for owners and technicians to effectively maintain and repair their Yanmar marine equipment.