This manual covers the HINO WO6D-TI and WO6D-TI-II series marine diesel engines. These engines are 5.8L, 6-cylinder in-line, water-cooled, four-cycle units featuring overhead valve (OHV) design, and are equipped with turbocharging and intercooling for enhanced performance. Specifically, the manual details the 5.8L engine variant producing 187KW (250HP) and the 5.8L variant producing 231KW (310HP). These engines are engineered for robust marine applications, offering reliable power and efficiency. The purpose of this workshop service repair manual is to provide comprehensive guidance for the maintenance, repair, and troubleshooting of the HINO WO6D-TI and WO6D-TI-II marine diesel engines. It includes detailed procedures, technical specifications, and essential safety information. This manual serves as an indispensable resource for owners, mechanics, and technicians, enabling them to effectively maintain the optimal performance and longevity of their marine diesel engines.