This Workshop Service Repair Manual covers the Mercury Mariner 40 outboard motor, part of the Marathon generation. Designed as a gasoline-powered, water-cooled, 2-cylinder engine producing 40 horsepower, this outboard motor features a CDI ignition system, an alternator/stator charging system, and carburetor induction. Its propulsion system utilizes a splined propeller shaft, and it offers Forward, Neutral, and Reverse gear selection. The Mariner 40 is engineered for reliable performance and durability in marine applications, featuring an impeller-type water pump and a standard kill switch for safety. This comprehensive manual is intended for mechanical technicians and provides detailed information essential for the maintenance, repair, and troubleshooting of the Mercury Mariner 40 outboard motor. It includes guidance on lubrication, specifying marine gearcase lubricant, and outlines the operational parameters of its various systems, including the fuel and electrical components. By following the procedures and specifications within this English-language document, users can ensure optimal performance and longevity of their Mercury Mariner 40 outboard motor.