This workshop service repair manual covers the Yanmar 4JHE Series marine diesel engines, including the 4JHE, 4JH-TE, 4JH-HTE, and 4JH-DTE models. These robust, water-cooled, four-cylinder diesel engines are engineered for reliability in marine applications, with aspiration varying from naturally aspirated to turbocharged and intercooled configurations depending on the specific model variant. The Yanmar 4JHE Series is designed for demanding maritime use, offering dependable power and performance. This comprehensive manual provides essential information for the maintenance, diagnosis, and repair of your Yanmar marine diesel engine. It includes detailed sections on general information, care and safety, routine maintenance, systems descriptions, fault finding, test procedures, and specific overhauls of the fuel, cooling, lubrication, electrical, induction, exhaust, and base engine components. Designed for DIY individuals, professional technicians, and mechanics, this manual offers step-by-step repair procedures and comprehensive fault-finding guidance to ensure your engine operates at peak efficiency.