This manual provides comprehensive service and repair information for the Hino W04D, W040C-T, and W04C-TI marine engines. These engines are known for their robust engineering and reliability, making them a trusted choice for marine applications. This document is designed to be the definitive resource for maintaining and repairing these specific Hino engine models, ensuring their continued optimal performance. The purpose of this manual is to offer detailed, step-by-step instructions for a wide range of service procedures. It covers essential areas such as engine identification, general precautions, disassembly and assembly, maintenance schedules, and specific system servicing for the fuel, cooling, and exhaust systems. Additionally, it includes troubleshooting guides, servicing specifications, tightening torques, and electrical system diagnostics with wiring diagrams, making it an invaluable tool for both do-it-yourself owners and professional mechanics.