This manual covers the Mercury Mariner 210/240 HP M2 Jet Drive models manufactured between 1999 and 2004. These gasoline-powered, water-cooled outboard engines are designed for marine propulsion, featuring a jet drive transmission with forward, neutral, and reverse gears. They deliver either 210 or 240 horsepower, providing robust performance for various boating applications. The engineering of these Mercury engines emphasizes reliability and efficient operation on the water. The purpose of this English-language Service Repair Manual is to provide comprehensive guidance for the maintenance, repair, and technical understanding of the Mercury Mariner 210/240 HP M2 Jet Drive. It details essential procedures, technical specifications, and troubleshooting steps necessary for owners, mechanics, and technicians. By following the information contained within, users can ensure the optimal performance and longevity of their marine propulsion system.