This workshop service manual covers the International Harvester Hydro 186 Tractor, a robust piece of agricultural machinery known for its reliability. Produced during the late 1970s to early 1980s, this tractor is part of International Harvester's esteemed legacy of durable farm equipment. Its design emphasizes practical functionality and ease of maintenance, making it a valuable asset for various agricultural tasks. The Hydro 186 features a hydrostatic transmission, designed for efficient power delivery and operational flexibility. This comprehensive 303-page English-language manual provides detailed, step-by-step repair and service information for the International Harvester Hydro 186 Tractor. It covers all major systems, including the engine, hydrostatic transmission, hydraulic system, electrical diagnostics, cooling, fuel, and brake systems, as well as chassis and operator station components. The manual includes procedures for disassembly, assembly, adjustment, installation, testing, and preventative maintenance, supported by detailed illustrations, exploded diagrams, and factory-specified torque values. It is designed to assist mechanics and DIY individuals in maintaining and repairing the tractor, emphasizing accident prevention and the use of genuine parts.