This workshop repair service manual covers the Fiat 540 and 540DT tractors, produced approximately from the late 1970s to the early 1980s. These utility tractors, powered by likely naturally aspirated diesel engines from the Fiat 8040 series, were known for their robustness, simplicity, and reliability in agricultural and industrial applications. The 540DT designation indicates a 4-wheel drive configuration, enhancing its capability in demanding conditions. With an estimated horsepower range of 50-60 HP, these tractors were designed for a wide array of tasks, embodying the strong heritage of Fiat Trattori. This comprehensive English-language manual provides professional-level guidance for owners, operators, and mechanics, covering all models, engines, and transmission types. It details routine maintenance, advanced troubleshooting, and complete repair procedures for every major system, including the engine, lubrication, cooling, fuel, clutch, transmission, drive train, axles, brakes, steering, hydraulics, and electrical systems. Featuring hundreds of pages with detailed illustrations, diagrams, and step-by-step instructions, this manual is an indispensable resource for maintaining and repairing your Fiat 540 or 540DT tractor, ensuring its optimal performance and longevity.