2004 Komatsu PC78MR-6 Excavator Service Manual (P/N SEBM030602)

• Original OEM publication SEBM030602, printed in Japan, dated May 2004
• Documents the S4D95LE-3-A engine variant and associated control valve assemblies for serial numbers 1001 and up
• Contains 583 pages of factory-level technical specifications, maintenance standards, and hydraulic system diagrams
• Covers Steel shoe, Road liner, and Rubber shoe undercarriage configurations
• Features comprehensive exploded-view diagrams of the hydraulic pump, travel motor, control valve, and swing machinery
• Provides torque specs, fluid capacities, and pressure thresholds for quick shop-floor reference
• Explains the structural mechanics of the CLSS (Closed-center Load Sensing System), center swivel joint, electric control system, monitor system, boom hydraulic anti-burst valve, air conditioner unit, and power train
• Includes wiring diagrams, electrical circuit diagrams, specification dimensions drawings, working range drawings, hydraulic circuit diagrams, troubleshooting charts, and standard tightening torque tables

Component and System Documentation

This Komatsu PC78MR-6 PDF repair manual details the structure and function of the entire hydraulic system. Mechanics gain clear insights into the variable-capacity piston pumps and gear pumps. Dedicated chapters cover the testing and adjusting of travel motors, swing machinery, and the multi-control valve. The documentation also outlines exact maintenance standards for track frames, idlers, and rollers. Technicians will find precise guidance for component assembly parameters, with specific sections breaking down the PPC lock solenoid valve, brake accumulators, and various EPC valves. By providing step-by-step procedures for complex tasks—such as testing and adjusting fuel injection timing, adjusting valve clearances, measuring blow-by pressure, and safely bleeding air from the hydraulic circuits—this manual allows your shop to execute critical diagnostics in-house rather than outsourcing to expensive dealer services. Please note that while this text provides excellent reference data for troubleshooting, you must always consult a certified technician before initiating any heavy equipment service to ensure workplace safety.

Specification and Reference Data

Accurate reference data is critical for daily workshop operations. Direct access to factory-specified protocols, such as standard value tables for the chassis and testing procedures for the PC and LS valves, prevents costly trial-and-error parts replacement. This publication lists comprehensive torque tables for metric bolts, flared nuts, split flange bolts, and O-ring boss piping joints. Factory hydraulic specifications for the PC78MR-6 are set at 26.5 MPa (270 kg/cm²) for work equipment and travel circuits. The swing and blade circuits operate at a distinct 21.1 MPa (215 kg/cm²). The manual also details exact system fluid requirements, specifying a 10.5-liter cooling system and a 120-liter hydraulic tank capacity.