This manual covers the Yanmar 3YM30, 3YM20, and 2YM15 marine diesel engines. These engines are known for their robust construction, reliable performance, and efficient operation, making them ideal for a wide range of marine applications. Engineered for durability and ease of maintenance, Yanmar engines provide dependable power for recreational and commercial vessels. This comprehensive service and repair manual provides detailed information for the maintenance and repair of your Yanmar marine diesel engine. It includes sections on general maintenance, troubleshooting, engine and transmission service, brake systems, electrical systems, cooling systems, fuel systems, and more. This manual is an essential resource for owners, mechanics, and technicians to ensure the optimal performance and longevity of their Yanmar engines.