This manual covers Yanmar Marine Inboard Engines, specifically all QM series models and engine types. Designed for service, repair, and maintenance, these engines are built with engineering quality and reliability in mind, ensuring consistent performance for marine applications. This comprehensive guide is intended to support owners and technicians in understanding and maintaining their Yanmar marine propulsion systems. The purpose of this English-language Service and Repair Shop Manual is to provide detailed, step-by-step instructions, accompanied by pictures and wiring diagrams, for all servicing, repairs, and routine maintenance jobs. It is structured to be very easy to use, even for individuals with basic computer skills, and enables users to perform their own servicing and repairs, leading to significant savings on costs. This manual serves as an essential diagnostic aid, helping users understand engine parts and repair procedures for their Yanmar marine inboard engines.