Komatsu N-855-C, NT-855-C, and NTA-855-C Diesel Engine Shop Manual (PN 09–84(01)10431, SEBE6710A03)

• Covers the Komatsu-Cummins N-855-C, NT-855-C, and NTA-855-C diesel engine series utilized in PC300-1, HD320-2, and D85A-18 platforms.
• Official 279-page Komatsu PDF publication (SEBE6710A03), printed in Japan, dated September 1984.
• Includes 12 assembly-view schematics, 9 performance curves, and 4 comprehensive torque specification tables.
• Details testing and adjusting, disassembly and assembly, maintenance standard limits, repair and replacement procedures, and factory wiring diagrams.
• Explores the water pump, thermostat, air compressor, alternator, Cummins VS governor, and starting motor.
• Serves as the foundational technical reference documenting the transition from early N-855 setups to the turbocharged and after-cooled NTA variants.

Important safety notice: Always ensure industrial machinery is fully powered down, locked out, and depressurized before inspecting engine components or comparing internal systems against these reference materials.

Internal System Documentation

This service manual details the exact technical descriptions for major engine subsystems. It breaks down the intake, exhaust, fuel, and lubrication systems to give mechanics a clear look at factory layouts. You will find precise structural outlines of the cylinder block, crankshaft, and timing gear assemblies. The publication documents the operational function of turbochargers and after-coolers, supported by troubleshooting charts, lubrication system charts, and disassembly relationship network drawings. It also details the Cummins PT fuel pump and governor arrangements for various machine applications. Reference data is included for troubleshooting symptoms like reduced power, oil leaks, and abnormal hydraulic pressure. Instead of relying on expensive dealer labor, shop mechanics can utilize the step-by-step instructions to perform complex tasks like calibrating the PT fuel pump, adjusting the four-valve cylinder heads, and measuring critical gear backlash with dial gauges. This provides undeniable clarity for daily workshop tasks. It strictly covers engine structure, function, testing, maintenance, and repair procedures.

Engine Specification Highlights

Specifications cover multiple variants across industrial and heavy equipment applications. The cylinder head intake valve clearance for Engine No. 26100001–26155791 is documented at 0.41 mm in the cold state. Standard tightening torque for a 12 mm thread diameter bolt is specified at 112 ± 9.8 Nm. The engine dry weight varies by specific model configuration, landing between 1,450 kg and 1,750 kg. Equipping your technicians with this factory data prevents guesswork when determining if a component can be reused or must be scrapped, significantly cutting down on unnecessary replacement costs by providing exact standard clearances and repair limits. When servicing these specific powerplants, be aware of a few notable repair pitfalls. For instance, attempting to mate floating seal housings without the O-rings and seal rings properly in place beforehand will instantly crush the O-rings, leading to severe fluid leakage. Furthermore, incorrect centering between the engine and transmission during reassembly significantly increases stress on turning parts, accelerating component wear and causing potential shaft failure.