This comprehensive repair manual provides detailed instructions for servicing and overhauling MerCruiser stern drive units from 1978 to 1982. It covers specific models including MCM 120, 140, 165, 470, 485, 898, 228, and 260, with serial numbers ranging from 4891650 to 6216686. The manual also includes information on stern drive units with ratios of 1.98:1, 1.84:1, 1.65:1, and 1.50:1, with corresponding serial number ranges. The manual features step-by-step repair procedures, accompanied by clear illustrations, diagrams, and specifications, enabling you to effectively diagnose and resolve common issues. It covers a wide range of topics, including inspection, service, and overhaul of major components. The content is organized to aid in understanding the intricacies of these stern drive units. This manual is a valuable resource for experienced technicians who require detailed technical information in their work.

The 1978-1982 MerCruiser MCM 120-260 stern drive units represent a pivotal era in recreational boating, offering a reliable and powerful means of propelling pleasure craft. These units, encompassing a range of horsepower outputs from 120 to 260, were built with a focus on durability and ease of maintenance. Notably, they featured GM-sourced V8 engines, renowned for their robust construction and proven performance. The MCM 120-260 units were equipped with a variety of transmissions, including the BorgWarner Velvet Drive, renowned for its smooth and efficient power transfer. Coupled with a robust drive train, these units delivered a balance of power and fuel efficiency, making them popular choices for a wide range of boat types, from runabouts to cruisers. The MerCruiser MCM 120-260 stern drive units were also known for their user-friendly design. Their components were easily accessible, allowing for routine maintenance and repairs with relative ease. This practicality, combined with the inherent reliability of the GM-sourced engines, made these units a popular choice for both seasoned boat owners and those new to the boating world. The MCM 120-260 stern drive units, however, were not without their quirks. Early models were susceptible to issues related to the cooling system, particularly in the exhaust manifolds, and the drive train could require regular lubrication for optimal performance. Despite these minor shortcomings, the 1978-1982 MerCruiser MCM 120-260 stern drive units became a mainstay in the boating industry, providing dependable power and a smooth ride for countless boaters across the globe.