This manual pertains to the Hino W04D Marine Engine, designed for robust performance and reliability in marine applications. Engineered with precision, the W04D series represents a commitment to quality and durability, ensuring optimal operation for its intended use. Its advanced design and construction are intended to provide owners and operators with a dependable power source, backed by the engineering excellence Hino is known for. The purpose of this comprehensive workshop service manual is to provide detailed guidance for the maintenance, repair, and overhaul of the Hino W04D Marine Engine. It covers a wide range of topics, including routine servicing, diagnostic procedures, and in-depth repair instructions for various systems such as fuel, ignition, lubrication, and electrical components. This manual is an essential resource for technicians and owners alike, offering the necessary information to ensure the engine's continued performance and longevity, emphasizing safety precautions and the use of specialized tools where applicable.