Komatsu PC138US-8 PC138USLC-8 Hydraulic Excavator Shop Manual – PDF Download

Description

Komatsu PC138US-8 PC138USLC-8 Shop Manual

This Komatsu PC138US-8 PC138USLC-8 Hydraulic Excavator Shop Manual is a comprehensive service and repair resource covering the PC138US-8 and PC138USLC-8 models from serial number 20001 and up. Whether you are performing routine maintenance, diagnosing a fault code, adjusting hydraulic pressures, or removing and reinstalling major assemblies, this manual provides the procedures, specifications, and reference data needed to complete the job correctly.

File Details

• Manual type: Shop Manual (Service Manual)
• Brand: Komatsu
• Models covered: PC138US-8, PC138USLC-8
• Serial number range: 20001 and up
• Engine: Komatsu SAA4D95LE-5 diesel engine
• Language: English
• Page count: 959 pages
• File format: PDF
• Publication date: 2007

Chapters Covered

• Index and Foreword — safety notices, how to read the shop manual, terms for maintenance standard, handling of electric equipment and hydraulic components, connectors used for engines, electric wire codes, standard tightening torque tables
• Specification — dimension drawings, working range diagrams, specifications, list of weights, fuel/coolant/lubricant table
• Structure, Function and Maintenance Standard — Engine and Cooling System: engine mount, PTO, cooling system
• Structure, Function and Maintenance Standard — Power Train: swing circle, swing machinery, track frame
• Structure, Function and Maintenance Standard — Undercarriage and Frame: idler cushion, idler, track roller, carrier roller, sprocket, track shoe
• Structure, Function and Maintenance Standard — Hydraulic System Part 1: equipment layout drawing, valve control, hydraulic tank and filter, hydraulic pump
• Structure, Function and Maintenance Standard — Hydraulic System Part 2: control valve, CLSS, functions and operation by valve
• Structure, Function and Maintenance Standard — Hydraulic System Part 3: PPC valve, swing motor, travel motor, center swivel joint, solenoid valve, PPC accumulator, holding valve, multi-control valve
• Structure, Function and Maintenance Standard — Work Equipment: dimensions of components, hydraulic cylinder
• Structure, Function and Maintenance Standard — Cab and Its Attachments: air conditioner
• Structure, Function and Maintenance Standard — Electrical System: electronic control system, monitor system, KOMTRAX system, sensors
• Standard Value Table — engine related parts and chassis related parts
• Testing and Adjusting — tools, engine speed, exhaust temperature, exhaust gas color, valve clearance, compression pressure, blow-by pressure, engine oil pressure, fuel system, alternator belt, swing circle bearing clearance, air conditioner compressor belt, track shoe tension, work equipment/swing/travel circuit oil pressure, control circuit basic pressure, pump PC and LS control circuit pressures, solenoid valve output pressure, PPC valve output pressure, hydraulic drift check, travel deviation, residual pressure release, oil leakage, air bleeding, cab tipping stopper, mirrors
• Testing and Adjusting Part 2 — special functions of machine monitor
• Testing and Adjusting Part 3 — engine controller voltage circuit handling, preparation for electrical troubleshooting, diode testing, PM Clinic service
• Troubleshooting — failure code table, fuse locations, general troubleshooting information, wiring table for connector pin numbers, T-adapter box and table
• Troubleshooting by Failure Code Part 1 — engine controller lock cautions, charge voltage low, engine oil pressure low, engine oil level low, engine coolant overheat, hydraulic oil overheat, ECM critical internal failure, Ne and Bkup speed sensor error, charge air pressure sensor, throttle sensor, coolant temperature sensor, charge air temperature sensor, sensor supply voltage, ambient air pressure sensor, engine overspeed, IMV/PCV1, injector system open/short errors
• Troubleshooting by Failure Code Part 2 — injector drive circuit error, sensor supply 1 volt errors, engine oil pressure switch abnormality, battery voltage errors, rail pressure errors, Ne speed sensor error, Bkup speed sensor phase error, persistent data lost, Bkup speed sensor error, KOMNET datalink timeout, throttle sensor supply voltage, rail pressure very low, IMV solenoid abnormality, battery relay drive short, personal code relay abnormality, GPS antenna disconnection, pump solenoid power low, 5V sensor power abnormalities
• Troubleshooting by Failure Code Part 3 — CAN disconnection, camera power supply short circuit, GPS module error, hydraulic oil sensor short, pump pressure sensor abnormality, travel PPC pressure sensor abnormalities, blade PPC pressure sensor abnormalities, overload sensor abnormality, travel alarm short circuit, travel speed solenoid, swing brake solenoid, travel junction solenoid, merge-divider solenoid
• Troubleshooting by Failure Code Part 4 — PC-EPC solenoid, service current EPC, wiper working/parking abnormality, washer drive, wiper drive short circuits
• Troubleshooting of Electrical System (E-mode) — machine monitor displays, engine start, preheater, automatic warm-up, work equipment/swing/travel lock, precaution lights, emergency stop items, gauges, display contents, function switches, auto-decelerator, working mode, travel speed, alarm buzzer, windshield wiper and washer, swing holding brake, travel alarm, air conditioner, service meter, service mode, monitoring function, KOMTRAX system
• Troubleshooting of Hydraulic and Mechanical System (H-mode) — system chart, speed/power issues, engine speed drops, no work equipment/travel/swing movement, abnormal noise from hydraulic pump, fine control, boom/arm/bucket speed and power, single operation, hydraulic drift, time lag, compound operation, travel deviation, travel speed, steering, track movement, swing issues, swing acceleration/speed, overrun, shock, sound, swing hydraulic drift, attachment circuit flow rate
• Troubleshooting of Engine (S-mode) — starting performance, engine does not start, engine does not pick up smoothly, engine stops during operation, engine does not rotate smoothly, engine lacks output, black exhaust smoke, excessive oil consumption, oil contamination, excessive fuel consumption, oil in coolant, oil pressure drops, oil level rises, coolant temperature too high, abnormal noise, vibration
• Disassembly and Assembly — how to read the manual, list of adhesives, special tool list, sketches of special tools; removal and installation of fuel supply pump, fuel injector, front oil seal, rear oil seal, cylinder head, radiator, aftercooler, work equipment oil cooler, engine and work equipment pump, fuel tank; travel motor and final drive, swing motor and swing machinery, swing circle, track roller, idler, recoil spring, track shoe, sprocket, revolving frame, counterweight, center swivel joint, hydraulic tank, hydraulic pump, control valve, work equipment PPC valve, travel PPC valve, hydraulic cylinder, work equipment, operator cab, cab glass, front window, floor frame, air compressor, air conditioner condenser, air compressor unit, machine monitor, pump controller, engine controller, KOMTRAX communications module
• Diagrams and Drawings — hydraulic circuit diagram, electrical circuit diagram, connectors table and arrangement drawing

The Komatsu PC138US-8 PC138USLC-8 Hydraulic Excavator Shop Manual is a deep technical resource covering every major system on these machines. From the Komatsu SAA4D95LE-5 diesel engine and its cooling system, through the power train, undercarriage, and the complete hydraulic system with CLSS control, to the electrical and electronic control systems, this manual gives technicians and mechanics the structure, function, and maintenance standard information needed to understand how each component works and how to service it correctly.

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What This Manual Enables You to Do

With this shop manual, you can diagnose and repair a wide range of issues on the PC138US-8 and PC138USLC-8. The troubleshooting sections are organized by failure code, by electrical system symptom, by hydraulic and mechanical system symptom, and by engine symptom, making it possible to trace a fault from the code shown on the machine monitor all the way to the failed component.

You can test and adjust engine speed, valve clearance, compression pressure, blow-by pressure, engine oil pressure, fuel pressure, alternator belt tension, swing circle bearing clearance, air conditioner compressor belt tension, track shoe tension, and the oil pressure in the work equipment, swing, and travel circuits. You can test control circuit basic pressure, pump PC control circuit pressure, pump LS control circuit pressure, solenoid valve output pressure, and PPC valve output pressure. You can adjust the play of the work equipment and swing PPC valves, test and adjust travel deviation, and check for hydraulic drift of the work equipment.

The disassembly and assembly chapters cover removal and installation of the fuel supply pump, fuel injectors, front and rear oil seals, cylinder head, radiator, aftercooler, work equipment oil cooler, engine and work equipment pump, fuel tank, travel motor and final drive, swing motor and swing machinery, swing circle, track roller, idler, recoil spring, track shoe, sprocket, revolving frame, counterweight, center swivel joint, hydraulic tank, hydraulic pump, control valve, work equipment PPC valve, travel PPC valve, hydraulic cylinder, work equipment, operator cab, cab glass, front window, floor frame, air compressor, air conditioner condenser, air compressor unit, machine monitor, pump controller, engine controller, and KOMTRAX communications module.

Why Correct Procedures and Specifications Matter

Hydraulic excavators operate under high pressure and heavy loads. The PC138US-8 and PC138USLC-8 use a variable displacement piston pump system with CLSS (Closed Center Load Sensing System) control, and the control valve, PPC valves, and electronic control system all work together to manage pump delivery and actuator movement. Incorrect adjustment of the LS valve, PC valve, or main relief valve can lead to poor performance, overheating, or damage to hydraulic components. Incorrect tightening torques on high-pressure fuel pipes, hydraulic hoses, and structural bolts can cause leaks, failures, or safety hazards.

This Komatsu PC138US-8 PC138USLC-8 service manual provides the standard values, repair limits, clearances, and tightening torques needed to carry out repairs and adjustments correctly. The failure code troubleshooting sections help identify the root cause of a problem rather than replacing parts by guesswork, saving time and money.

Instant PDF Delivery

The Komatsu PC138US-8 PC138USLC-8 Hydraulic Excavator Shop Manual is delivered as an instant PDF download after purchase. There is no shipping, no waiting for a physical book, and no restrictions on where you can use it. The file can be viewed on any device that supports PDF — laptop, desktop, tablet, or smartphone — and pages can be printed for use in the workshop. Keep it on your computer for quick reference during diagnostics, or print the sections you need for the job at hand.