Komatsu PC128US-2, PC138US-2, PC138USLC-2 Hydraulic Excavator Shop Manual (P/N SEBM018419)

• A 1,029-page PDF of Komatsu America shop manual SEBM018419, covering the PC128US-2 S/N 5001–7730 Avance and S/N 7731-up GALEO, PC138US-2 S/N 4501-up GALEO, and PC138USLC-2E0 S/N 1001-up GALEO (shown internally as PC138USLC-2).
• Separates the major serial-dependent builds, including S4D102E-1 and SAA4D95LE-3-A engine applications, the PC138USLC-2 change at S/N 1501, standard and blade-equipped machines, North American and KUK specifications, and serial-specific attachment circuits.
• Explains the HPV95 piston pump, CLSS hydraulic control, main control valve, self pressure-reducing valve, PPC circuits, center swivel joint, travel motor/final drive, swing motor, and hydraulic drift-prevention valves through operating descriptions and section views.
• Provides factory testing and adjustment coverage for engine condition, hydraulic pressure and leakage, travel behavior, undercarriage wear, system bleeding, and residual-pressure release.
• Details major factory repair work, from engine/main-pump, cooling-module, swing, travel, and undercarriage removal to internal control-valve, PPC-valve, hydraulic-cylinder, recoil-spring, idler, and swing-machinery reassembly.
• Includes serial-specific electrical, hydraulic/mechanical, monitor, communication, CR700 controller, pump-control, input-signal, and engine troubleshooting, with connector data, circuit diagrams, monitor-mode checks, and arm-crane boom-angle potentiometer correction.

This January 2005 issue carries a 2007 Komatsu copyright line and incorporates revised pages throughout.

Serial-Specific Coverage

The manual does not group every PC128US-2 under one generic procedure set. Machines from S/N 5001–7730 are identified as the Avance build, while S/N 7731 and up is the GALEO build. The older machines retain their own E-mode electrical and M-mode monitor troubleshooting. Later machines add CR700 deceleration and pump-control diagnosis, F-mode input-signal checks, N-mode S-NET communication troubleshooting, and expanded monitor-panel functions.

Electrical drawings are divided again for PC128US-2 S/N 5001–6300, 6301–7730, 7731–7874, and 7875-up. The PC138USLC-2 material also separates S/N 1001–1500 from S/N 1501-up because the engine and related control specifications change from S4D102E-1 to SAA4D95LE-3-A. These breaks matter when choosing wiring, test values, controller logic, or repair procedures.

Workshop Procedures and Reference Data

Testing and adjusting begins with standard-value tables for the engine, chassis, and electrical components, then moves into usable shop procedures. Coverage includes a PM Clinic inspection form, engine-speed and exhaust-smoke checks, blow-by and oil-pressure testing, valve-clearance and fuel-injection-timing work, PC and LS valve output tests, PPC and solenoid pressure checks, travel-deviation diagnosis, swing-circle clearance, sprocket wear, motor leakage, and post-repair operational checks.

The disassembly chapter clearly distinguishes removal-and-installation work from assemblies that receive full internal teardown and reassembly coverage. Internal repair sections are provided for the center swivel, swing machinery, recoil spring, idler, track roller, control valve and its LS/pressure-compensation valves, work-equipment and travel PPC valves, and hydraulic cylinders. Separate removal sections cover the engine/main-pump assembly, cooling packs, travel motor/final drive, hydraulic tank, work equipment, cab, stuck glass and front window, floor frame, A/C components, counterweight, monitor panel, and controllers.

Tooling is documented by part number rather than left to general recommendations. Examples include the 799-101-5002 hydraulic tester, 790-601-8000 T-adapter kit, 790-502-1003 cylinder repair stand, and 799-703-1200 A/C service tool kit, along with component-specific pullers, installers, push tools, and locally fabricated tool drawings.

This is the chassis shop manual, not a complete stand-alone engine overhaul volume. It contains engine-related specifications, testing, troubleshooting, complete engine/main-pump removal, and selected cylinder-head and injection-pump procedures for the applicable SAA4D95LE-3-A machines. Full internal engine repair requires the matching engine manual.

Diagrams, Limits, and Repair Cautions

Representative technical references include the HPV95 pump section view, CLSS hydraulic circuit, travel-motor/final-drive section view, connector arrangement and pin table, serial-specific two- and three-sheet machine wiring diagrams, and blade-plus-one-actuator or KUK two-actuator attachment circuits. Standard and blade-equipped machines, North American and KUK builds, and breaker or one-/two-service-valve attachment arrangements are distinguished where separate data is provided.

Maintenance-standard chapters supply inspection criteria and repair limits for the swing machinery and circle, track frame, idler and rollers, sprocket and shoes, pump, control valve, travel and swing motors, center swivel, PPC valves, hydraulic cylinders, and work equipment. General and component-specific torque tables, fluid and lubricant data, clearances, pressure-test specifications, electrical test values, and wear limits are also included.

The control-valve repair material warns that spools and pressure-compensation parts are directional and are not interchangeable; mixing them can cause incorrect valve operation. Hydraulic-cylinder assembly notes protect the packing, dust seals, O-rings, and backup rings from handling damage that can lead to leakage after repair. Before testing or repair, lower and support the work equipment, release residual hydraulic pressure, isolate the battery, and use correctly rated lifting equipment for heavy assemblies.