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

This 748-page PDF is Komatsu document CEBM207077, covering the PC300-5/PC400-5 excavator family with LC, LC-5K, MIGHTY, HD, and PC400 Loading Shovel configurations. 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.

• Machine and serial coverage: PC300-5 and PC300LC-5, S/N 20001 and up; PC300-5/PC300LC-5 MIGHTY and PC300HD-5, S/N 21401 and up; PC300LC-5K, S/N K20001 and up; PC400-5 and PC400LC-5, S/N 20001 and up; PC400-5/PC400LC-5 MIGHTY and PC400HD-5, S/N 20603 and up; plus PC400-5 and PC400LC-5 Loading Shovel versions.
• OLSS and main-pump service: Explains the HPV160 + 160 front and rear pumps, servo valves, TVC valve, CO/NC valves, charging pump, and main control circuit. Factory procedures cover work-equipment, swing, and travel pressure tests, pump-control checks, servo-piston stroke measurement, travel-deviation adjustment, hydraulic-drift isolation, air bleeding, and residual-pressure release.
• Travel and swing repair: Includes final drives, HMV280ADT and HMV355ADT travel motors, the KMF160 swing motor, swing machinery and circle, center swivel, brakes, track components, and recoil spring. Procedures cover removal and installation, disassembly and reassembly, bearing and contact checks, shim selection, and final inspection.
• Engine-related workshop procedures: Covers the SA6D108-1 used in the PC300 and the S6D125-1 used in the PC400, with valve-clearance adjustment, compression testing, fuel-injection timing, governor-motor travel, and speed-sensor adjustment. It also includes removal and installation of the cylinder head, injection pump, nozzle holders, turbocharger, water pump, oil seals, and related cooling components.
• Electronic control and fault finding: Documents engine throttle control, the PEMC pump-and-engine mutual control system, EMACC monitor functions, pump-controller signals, model-code and self-diagnostic displays, connector locations, and structured E-, C-, F-, H-, and P-series troubleshooting charts.
• Work equipment and hydraulic component repair: Covers the main control, relief, PPC, shuttle, and boom-holding valves; hydraulic cylinders; boom, arm, bucket, cab, and counterweight; PC400 Loading Shovel bottom-dump cylinders and linkage; hydraulic-circuit flushing; and post-repair checks.

Serial-Specific Hydraulic and Electronic Logic

The hydraulic and electrical diagrams are not treated as one universal layout. Early PC300 S/N 20001-21400 and PC400 S/N 20001-20602 material is separated from the 21401-and-up and 20603-and-up circuits used with later, MIGHTY, and HD configurations. The control chapters also explain PNC pump-neutral control, power maximizing, auto-deceleration, automatic warm-up and overheat protection, and swing and travel control logic.

Drawings, Standards, and Tooling

Named visual references include the early and late hydraulic circuit diagrams, the PC400 Loading Shovel hydraulic circuit, PC300LC-5 K-prefix electrical wiring and circuit diagrams, the engine throttle controller circuit, pump-controller and monitor-system schematics, and section or exploded views of the main pump, control valve, final drive, and travel and swing motors. Electrical pages add connector-location drawings, pin tables, and alphabetical circuit indexes.

Factory repair data include component-specific torque tables, total and refill capacities, hydraulic test criteria, electrical standard values, component weights, leakage limits, clearances, wear limits, and model-specific maintenance standards. The special-tool lists identify the 791-630-3000 master-pin remover/installer and 799-301-1600 travel-motor oil-leak tester, along with seal installers, pullers, repair stands, servo-stroke gauges, and press tooling.

Scope and Repair Notes

This is the chassis volume. It contains the engine procedures listed above, but not a complete internal engine overhaul, and Komatsu states that separate engine, electrical, and attachment volumes are needed for complete all-system repair coverage.

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

Before hydraulic or work-equipment repair begins, lower or positively support the attachment, release residual circuit pressure, isolate the machine, and use rated lifting equipment for the listed component weights.