The Sisu Diesel 320, 420, 620, and 634 Engine Full Service Repair Manual is a comprehensive guide for repair, maintenance, rebuilding, refurbishing, and restoring your Sisu diesel engine. It provides detailed information on all diagnostic and repair procedures, covering the same information used by professional technicians and mechanics. This manual is ideal for experienced mechanics and those looking to delve deeper into the workings of these engines.

The manual includes detailed step-by-step instructions for each repair procedure, numbered for easy following. Notes, cautions, and warnings are clearly highlighted throughout the manual to ensure safe and effective repair work. Illustrations, drawings, and photographs accompany each procedure, providing visual guidance and detailed examination of parts. Enlarged insets are provided for close-up views of critical components.

The manual's organized table of contents allows for quick navigation to the necessary information. Troubleshooting and electrical service procedures are combined with detailed wiring diagrams for easy diagnosis and repair of electrical system problems. This comprehensive manual serves as an essential tool for anyone involved in the repair and maintenance of Sisu Diesel 320, 420, 620, and 634 engines.

## Sisu Diesel 320, 420, 620, 634: Robust Workhorses for Demanding Tasks

The Sisu Diesel 320, 420, 620, and 634 are a series of heavy-duty trucks renowned for their rugged construction, powerful engines, and impressive reliability. These trucks were manufactured by Sisu Auto, a Finnish company with a rich history in the automotive industry, known for producing vehicles that can withstand the harshest conditions and demanding workloads. The series boasts a range of engine options, with the 320 typically featuring a 6-cylinder diesel engine, while the 420, 620, and 634 models offering larger 8-cylinder options. These powerful engines deliver impressive torque, enabling the trucks to handle heavy loads with ease, making them ideal for applications like construction, logging, mining, and long-haul transportation.

While marketed as "trucks," the Sisu Diesel models can be further categorized into different configurations based on their intended use. The Sisu 320, for example, was often employed as a construction truck, featuring a robust chassis and a spacious cab designed for demanding work sites. The Sisu 420 and 620 typically served as long-haul trucks, boasting a more aerodynamic design and comfortable interiors for drivers undertaking extensive journeys. The Sisu 634, known for its exceptional power and off-road capabilities, was often deployed as a military vehicle or a heavy-duty hauler for challenging terrains. Despite their different configurations, all Sisu 320, 420, 620, and 634 models share a common trait: they are built to last, with high-quality materials and robust design that ensures they can withstand years of heavy use and demanding environments.