This manual covers the Yanmar 3YM30, 3YM20, and 2YM15 diesel engines. These engines are vertical, water-cooled, 4-cycle, naturally aspirated units designed for reliable operation. The 3YM30 features a 1.150-liter displacement, the 3YM20 a 0.854-liter displacement, and the 2YM15 a 0.570-liter displacement. Their robust construction and efficient design make them suitable for various applications requiring dependable power. This comprehensive Workshop Service Manual and Operating Manual in English provides detailed information for the maintenance and repair of your Yanmar engine. It includes sections on general information, engine components, fuel and lubrication systems, cooling, electrical systems, and troubleshooting. With high-definition diagrams and a well-structured format, this manual is an essential resource for both professional mechanics and non-experienced users aiming to ensure the optimal performance and longevity of their Yanmar engines.