This Service Repair Manual covers the Mercury Mariner, a 4-stroke outboard engine designed for marine propulsion. This engine features a water-cooled system and delivers 40 horsepower, with an outboard lower unit transmission offering Forward, Neutral, and Reverse gears. The Mercury Mariner is engineered for reliability and performance in various aquatic environments. This manual provides comprehensive guidance for the maintenance and repair of your Mercury Mariner outboard engine. It details essential procedures, technical specifications, and troubleshooting steps necessary for optimal performance and longevity. By following the instructions within this English-language document, owners and technicians can effectively manage routine servicing, address potential issues, and ensure the continued operational integrity of the engine.