This workshop service manual covers the Mercury Mariner 3.0 Marathon Outboard motor, designed for boating applications. This gasoline-powered, water-cooled outboard motor features a 3.0 L displacement and an outboard drive transmission with forward, neutral, and reverse gears. The engineering quality and reliability of Mercury outboards are well-established, providing dependable performance for marine enthusiasts. This comprehensive manual provides detailed information for the repair and overhaul of your Mercury Mariner 3.0 Marathon Outboard. It includes essential maintenance procedures, troubleshooting guidance, and technical specifications to ensure optimal performance and longevity. Owners, mechanics, and technicians will find the step-by-step instructions and diagrams invaluable for routine servicing and complex repairs, ensuring the continued reliability of the unit.