This manual covers the Yanmar 1GM10(C), 2GM20(F)(C), 3GM30(F)(C), and 3HM35(F) marine diesel engines. These engines are engineered for reliable marine propulsion, offering robust performance and durability for a variety of vessel applications. Yanmar's commitment to quality ensures these engines are a dependable choice for demanding marine environments. This comprehensive service and repair workshop manual provides detailed information essential for maintaining and repairing your Yanmar marine diesel engine. It includes step-by-step instructions, detailed photos, and diagrams covering all repairs, servicing, and troubleshooting procedures. This resource is designed to assist owners, mechanics, and technicians in ensuring optimal performance and longevity of their Yanmar engines.