This workshop service manual covers the Mercury Mariner 40 Marathon, a 2-cylinder outboard engine designed for marine propulsion. This engine delivers 40 horsepower and features a water-cooled system. Its robust construction and reliable performance make it a suitable choice for various boating applications. The outboard lower unit provides forward, neutral, and reverse gear selection, ensuring versatile maneuverability on the water. This comprehensive English-language manual is intended for technicians and provides detailed information on the repair and overhaul of the Mercury Mariner 40 Marathon. It covers essential procedures and technical data necessary for maintaining the engine's optimal performance and longevity. By following the guidelines within this manual, technicians can ensure accurate diagnostics, effective repairs, and proper servicing of the unit.