This manual covers Westerbeke Universal Marine Power Units, specifically the M-30, M-40, and M-50 models. These diesel-powered marine engines are designed for reliable marine power generation, utilizing internal combustion technology. Westerbeke is known for its robust engineering and dependable performance in demanding marine environments, ensuring that these power units meet the rigorous requirements of maritime applications. This comprehensive factory service and repair manual provides essential information for maintaining and troubleshooting your Westerbeke marine power unit. It includes detailed sections on specifications, preventive maintenance, construction, lubrication, cooling and fuel systems, electrical systems, disassembly and reassembly, the dynamo and regulator, and troubleshooting. With step-by-step instructions, exploded diagrams, and clear illustrations, this English-language manual is an indispensable resource for owners, mechanics, and technicians.