This comprehensive workshop manual provides detailed technical information and repair procedures for Sisu Diesel 320, 420, 620, and 634 engines. It covers a wide range of topics, including engine specifications, troubleshooting, maintenance schedules, component identification, disassembly, reassembly, and repair procedures. The manual is written in clear and concise language, making it easy to understand and follow. With detailed illustrations and diagrams, this manual is an essential resource for mechanics, technicians, and anyone who needs to maintain or repair these engines. It offers step-by-step guidance and valuable insights into the inner workings of these powerful Sisu Diesel engines.

The Sisu Diesel 320, 420, 620, and 634 engines are powerful and robust powerplants designed for heavy-duty trucks. These engines were manufactured by Sisu Auto, a Finnish company renowned for its durable and reliable vehicles. These engines were popular choices for long-haul trucking, construction, and other demanding applications, known for their high torque output and impressive fuel efficiency. The Sisu Diesel engine lineup encompassed a range of displacement options, with the 320, 420, and 620 models offering different power outputs to cater to specific needs. The 634 engine, a later addition to the range, featured a more advanced design and enhanced performance characteristics. These engines were primarily equipped with turbochargers, intercoolers, and other technologies to optimize performance and fuel economy. They featured durable construction with cast-iron blocks and forged steel crankshafts, designed to withstand the rigors of heavy-duty operation. The Sisu Diesel engines were also known for their reliability and longevity, a testament to their robust design and high-quality components. While the Sisu Diesel brand ceased production of its own engines, these models remain popular choices in the aftermarket for their robust performance and availability of parts. The Sisu Diesel 320, 420, 620, and 634 engines are valuable assets in the heavy-duty truck industry, offering a combination of power, efficiency, and durability that has made them a lasting legacy in the world of commercial vehicles.