This comprehensive Workshop Service Repair Manual provides detailed instructions and high-quality diagrams for servicing and repairing the Sisu 320, 420, 620, and 634 series diesel engines. It covers a wide range of components, including the cylinder block, flywheel housing, cylinder head, valve mechanism, crankshaft, connecting rods and pistons, counterbalance (420), flywheel, timing gear assembly, lubrication system, cooling system, inlet and exhaust system, fuel system, equipment and feeding tables, electrical system, and optional equipment. This manual is an essential resource for anyone who wants to understand and maintain these powerful engines, whether you are a professional mechanic or a DIY enthusiast. This manual is your complete guide for keeping your Sisu engine running smoothly and efficiently.

The Sisu 320, 420, 620, and 634 series diesel engines are robust and reliable powerplants renowned for their durability and performance in demanding applications. These engines were produced by Sisu Diesel, a Finnish company known for its expertise in heavy-duty machinery. These engines were widely utilized in various heavy-duty vehicles such as trucks, buses, construction equipment, and marine vessels. The Sisu engine series is recognized for its sturdy construction, featuring cast iron cylinder blocks and heads, resulting in exceptional strength and longevity. They're also known for their fuel efficiency and low emissions, meeting stringent environmental standards.

The Sisu 320, 420, 620, and 634 series engines offer a range of power outputs depending on the specific model and configuration. They are typically equipped with turbochargers for enhanced power and fuel efficiency. The engines feature a variety of advanced technologies, such as electronic control systems, to optimize performance and ensure reliable operation. Sisu engines are renowned for their durability and ability to endure harsh operating conditions. They are designed for demanding applications requiring consistent power and reliability. The robust construction and high-quality materials contribute to their long service life. These engines are also known for their ease of maintenance, thanks to their straightforward design and readily accessible components. The availability of comprehensive workshop service manuals and parts support further enhances the convenience and efficiency of maintaining these engines.