This service repair manual covers the Yanmar 4CHE, 6CHE, 6CH-HTE, 6CH-DTE, and 6CH-UTE marine diesel engines. These engines are engineered for reliable performance in marine applications, offering robust construction and efficient operation essential for demanding maritime environments. This manual is designed to provide comprehensive support for the maintenance and repair of these specific Yanmar marine diesel engine models. The purpose of this manual is to serve as a definitive guide for owners, mechanics, and technicians. It details essential procedures for maintaining the optimal condition of your Yanmar marine diesel engine. Covered topics include general information, detailed maintenance schedules, cylinder head and valve systems, engine proper, lubrication, cooling, fuel, intake and exhaust systems, electrical systems, engine installation, marine gear operation, and troubleshooting. This resource ensures that all aspects of repair and upkeep are addressed with clarity and precision.