This manual covers the Mitsubishi S4Q2 Diesel Engine, a robust 4-cylinder diesel engine designed for use in forklift trucks. Specifically compatible with models FD10N, FD15N, FD18N, and FD20CN, this engine is engineered for reliability and efficient operation in demanding industrial environments. Its construction emphasizes durability, ensuring consistent performance and longevity for the equipment it powers. This Service Repair Manual provides comprehensive guidance for the maintenance and repair of the Mitsubishi S4Q2 Diesel Engine. It details essential procedures, technical specifications, and troubleshooting information necessary for proper upkeep. Owners, technicians, and mechanics will find this manual an indispensable resource for ensuring the optimal performance and extending the service life of their forklift trucks equipped with this engine.