The Yanmar 4LH Series represents a line of robust diesel engines engineered for reliable performance. These in-line, 4-cylinder engines feature a direct injection fuel system and are water-cooled, designed to meet demanding operational requirements. While specific production years are not detailed, the series is known for its engineering quality and durability, making it a trusted choice for various applications requiring consistent power and efficiency. This service repair manual provides comprehensive instructions and procedures for the Yanmar 4LH Series engines. It covers essential areas including general engine information, the fuel injection equipment, intake and exhaust systems, lubrication and cooling water systems, reduction and reversing gears, remote control mechanisms, and the electrical system. The manual is intended to assist owners, mechanics, and technicians in performing effective maintenance, troubleshooting, and repairs, ensuring the continued optimal operation of the engine.