The 3YM20 is a marine diesel engine designed for reliable performance in maritime applications. This naturally aspirated, 3-cylinder engine offers a displacement of 0.57 L (570 cc) and a rated power output of 20 HP (14.7 kW) at 3200 RPM. It features indirect fresh water cooling and a forced lubrication system, ensuring durability and efficiency for boat owners. The engine's robust construction and engineering are hallmarks of commitment to quality and dependability on the water. This comprehensive Workshop Service Repair Manual provides detailed guidance for the 3YM20 marine diesel engine. It covers essential areas including general information, engine mechanical and electrical systems, fuel system, emission control, and troubleshooting. Step-by-step repair procedures and wiring diagrams are included to assist owners, mechanics, and technicians in maintaining and repairing the engine. The manual is presented in English and is fully printable, offering access for all Windows and Mac operating systems.