This manual provides comprehensive service and repair instructions for the Hino W04D marine engine. Designed for mechanics worldwide, it covers all major topics with step-by-step instructions, diagrams, illustrations, wiring schematics, and specifications. The Hino W04D marine engine is engineered for reliability and performance in marine applications, and this manual ensures that its maintenance and repair are conducted with the same precision used by authorized service departments. The scope of this manual is extensive, detailing engine identification, general precautions, maintenance checklists, and specific procedures for the engine body, fuel system, cooling system, fuel filter, electrical system, alternator, and regulator. It also includes essential troubleshooting guidance, servicing specifications, and tightening torques. This resource is invaluable for owners and technicians alike, offering the knowledge needed to perform diagnostics, maintenance, and repairs effectively, thereby saving time and expense.