Komatsu PC300-5 / PC400-5 Excavator Shop Manual, 1988–1995 (P/N CEBM207077)

Komatsu Shop Manual P/N CEBM207077 covers the PC300-5/PC400-5 hydraulic excavator family, including LC, LC-5K, MIGHTY, HD, and PC400 Loading Shovel configurations.

PDF Search, Bookmarks and Diagram Detail

Search and navigation: Text search works in many sections but does not capture every page, table value, or wiring label. Embedded bookmarks provide access to the main chapters and many individual procedures. Small wiring-diagram labels require zooming.

One printable English PDF contains 748 pages, including the original cover, one revision-list page, one manual-revision proposal form, and 35 blank pages.

OLSS Hydraulics, Electronic Diagnosis and Chassis Repair

These selected workshop topics provide a partial overview; starter and alternator removal and installation are also covered.

• OLSS and main pumps: HPV160 + 160 front and rear pumps, servo valves, TVC and CO/NC valves, charging pump, and pressure testing for work-equipment, swing, and travel circuits.

• Travel and swing: Final drives, HMV280ADT and HMV355ADT travel motors, KMF160 swing motor, and brakes, with step-by-step disassembly and reassembly procedures.

• Engine checks and adjustments: Valve-clearance adjustment, compression testing, fuel-injection timing, governor-motor travel, and engine-speed-sensor adjustment.

• Electronic fault finding: Engine throttle control, PEMC pump-and-engine control, EMACC monitoring, and E-, C-, F-, H-, and P-series troubleshooting charts.

• Hydraulic valves and cylinders: Main control, relief, PPC, shuttle, and boom-holding valves, plus hydraulic-cylinder disassembly, inspection, and assembly.

• Undercarriage repair: Track shoes, idlers, rollers, track frames, and recoil-spring assemblies, with removal procedures and model-specific maintenance standards.

• Work equipment and structures: Boom, arm, bucket, cab, counterweight, swing circle, and PC400 Loading Shovel bottom-dump cylinders and linkage, with removal, installation, and post-repair checks.

Komatsu prepared the manual for service personnel performing workshop repairs; its heavy-component, hydraulic, and electrical procedures are suited to experienced technicians with the lifting, pressure-testing, and electrical test equipment required for this class of machine.

Engine Service and Chassis-Volume Limits

The engine sections identify the SA6D108-1 for PC300 and S6D125-1 for PC400. Component removal and installation covers cylinder heads, injection pumps, nozzle holders, turbochargers, front and rear oil seals, water pumps, and related cooling assemblies. Radiator and hydraulic-oil-cooler procedures are included, along with PC300 aftercooler-core service.

This is the chassis volume, rather than a complete internal engine-overhaul manual. Komatsu explains that chassis, engine, electrical, and attachment volumes are needed for complete all-system repair coverage. The supplied volume includes the engine-related work and electrical diagnosis described here.

Serial-Specific Hydraulics and Electronic Control

Early PC300 S/N 20001–21400 and PC400 S/N 20001–20602 circuits are distinguished from the later 21401-and-up and 20603-and-up layouts used with later, MIGHTY, and HD configurations. These distinctions help technicians select the appropriate circuit and diagnostic information before testing.

Pump and drift diagnosis: The testing section covers main-pump control-pressure checks, servo-piston stroke measurement, travel-deviation adjustment, PPC output checks, air bleeding, and residual-pressure release. Hydraulic-drift tests distinguish cylinder-packing leakage from control-valve, boom-holding-valve, and PPC faults.

Control behavior: PNC pump-neutral control, power maximizing, auto-deceleration, automatic warm-up, overheat protection, and swing and travel control logic are explained alongside controller signals. Model-code and self-diagnostic displays connect operating symptoms with the appropriate troubleshooting charts.

Hydraulic-circuit flushing procedures distinguish contamination levels, including metal particles following component failure, and provide different flushing patterns for the documented conditions.

Travel, Swing and Assembly Checks

The repair sections go beyond component removal. They include bearing-clearance adjustment, cylinder-block/valve-plate and rocker-cam/cradle contact checks, shim and spacer selection, and final assembly inspections. Center-swivel repair and swing-machinery assembly are also covered.

The center-swivel instructions warn that careless rotor installation can damage the slipper-seal and oil-seal lips. During KMF160 swing-motor repair, bearings must remain with their matched sets, and a metal bar can damage the bearing outer race.

Circuit Drawings, Repair Standards and Tooling

Diagrams and connector references: Examples include early and late hydraulic circuit diagrams, the PC400 Loading Shovel hydraulic circuit, PC300LC-5 K-prefix electrical diagrams, and engine-throttle, pump-controller, and monitor-system schematics. Connector-location drawings, pin tables, and alphabetical circuit indexes support electrical fault tracing.

Section and exploded views show the main pump, control valve, final drive, and travel and swing motors. Factory reference data include component-specific torque tables, total and refill capacities, hydraulic test criteria, electrical standard values, component weights, leakage limits, clearances, and wear limits.

Special tools: Lists identify the 791-630-3000 master-pin remover/installer and 799-301-1600 oil-leak tester used in travel-motor work. Seal installers, pullers, repair stands, servo-stroke gauges, and press tooling are also listed.

Hydraulic and work-equipment repairs require positive attachment support, residual-pressure release, machine isolation, and lifting equipment rated for the listed component weights.

Selected Valve-Clearance and Servo-Stroke Data

At normal temperature, the engine standard-value table lists intake/exhaust valve clearances of 0.34/0.66 mm for the PC300 SA6D108-1 and 0.33/0.71 mm for the PC400 S6D125-1.

For pump-control diagnosis, the servo-piston measurement section gives approximate standard strokes of 8.9 mm for PC300 and 11.2 mm for PC400 under its high-idle, freely rotating track test condition. These values accompany the manual’s test conditions and inspection procedures.