This comprehensive service and repair manual covers Yanmar inboard QM, GM-HM, 4JH, and 4JH2 series engines and transmissions from 1975 to 1998. It's the same type of manual used by professional mechanics and technicians, providing detailed step-by-step instructions and highly detailed exploded diagrams and pictures to guide you through every repair, servicing, and troubleshooting procedure. This manual is a valuable resource for anyone who owns or maintains these Yanmar marine engines, offering detailed information to ensure proper and efficient maintenance and repair.

The Yanmar Inboards QM, GM-HM, 4JH & 4JH2 Series engines and transmissions represent a significant chapter in the history of marine propulsion. From 1975 to 1998, these robust and reliable powerplants propelled countless vessels, ranging from small sailboats to larger cruisers. Yanmar, known for its expertise in diesel engineering, meticulously designed these inboards to deliver exceptional performance and durability. The QM, GM-HM, 4JH & 4JH2 Series engines featured a range of displacements, horsepower outputs, and transmission options, catering to diverse boating needs. Their compact design and relatively low weight made them ideal for installation in a variety of hull types. These inboards were renowned for their smooth operation, fuel efficiency, and ease of maintenance, making them a popular choice among boat owners.

The Yanmar Inboards QM, GM-HM, 4JH & 4JH2 Series were powered by naturally aspirated, four-cylinder diesel engines, offering a balance of power and economy. The QM series, with its smaller displacement, excelled in smaller boats, while the GM-HM series provided more power for larger vessels. The 4JH and 4JH2 series, characterized by their increased displacement and power outputs, were ideal for heavier boats and demanding applications. These engines were often coupled with Yanmar's own transmissions, known for their durability and smooth shifting characteristics. With their robust construction and proven reliability, the Yanmar Inboards QM, GM-HM, 4JH & 4JH2 Series engines earned a reputation for longevity, routinely exceeding expectations even with regular use and demanding conditions. While production ceased in 1998, these engines continue to be popular choices for boat owners seeking power, reliability, and ease of maintenance.