Komatsu PC78MR-6 Excavator Shop Manual SEBM030601 (S/N 1001 & Up) – PDF Service & Repair Manual

Description

Komatsu PC78MR-6 Shop Manual SEBM030601 — Full Service & Repair Reference for S/N 1001 and Up

This is the complete Komatsu PC78MR-6 shop manual, document number SEBM030601, covering machine serial numbers 1001 and up. It is the working reference for testing, adjusting, disassembling, assembling and maintaining the PC78MR-6 excavator — the structure and function of each system, the maintenance standard tables that tell you when a part is out of tolerance, and the procedures to put everything back together to specification.

The PC78MR-6 mounts the S4D95LE-3-A engine. This book points you to the 95-3 Series Engine Shop Manual for engine-internal detail, while covering the machine side — pump, control valve, swing, travel, work equipment, hydraulics and the electronic control system — in full. Specifications and materials in this shop manual are subject to change without notice; use the version with the latest date.

File Details

• Manual type: Shop / Service manual
• Brand: Komatsu
• Model: PC78MR-6
• Serial number coverage: 1001 and up
• Engine: S4D95LE-3-A
• Document number: SEBM030601
• Language: English
• Page count: ~592 pages
• File format: PDF

Chapters Covered

• 01 — General
• 10 — Structure and Function, Maintenance Standard
• 20 — Testing and Adjusting
• 30 — Disassembly and Assembly
• 90 — Others

01 General

Specification dimension drawings, working range drawings, machine and engine specifications, the weight table and the list of lubricants and coolants. This is where the base numbers behind every procedure live — rated output, digging reach and depth, overall dimensions, bucket capacity, the mass of each major assembly, and fluid selection across ambient temperatures.

10 Structure and Function, Maintenance Standard

Explains what every component is, what it does, and the wear limits that decide when to act. Contents include the PTO and flywheel coupling, the cooling package with radiator and oil cooler, the hydraulic pump and control valve layout, swing circle and swing machinery reduction, track frame and idler cushion, idler, track roller, carrier roller, sprocket and track shoes (city pad, road liner, rubber shoe and triple grouser), boom, arm, bucket link, bucket and blade assemblies, the work equipment cylinders, hydraulic tank and oil filter, centre swivel joint, travel motor, the 6-spool solenoid bank with EPC, check and control relief valves, and the CLSS closed-centre load sensing system covering the LS valve, PC valve and pressure compensation valve. Maintenance standard tables give basic dimensions, standard and allowable clearance, and the correct remedy — replace, overlay, repair or adjust.

20 Testing and Adjusting

The measurement and setting section of the manual. It opens with the standard value tables for engine and chassis, then works through measuring engine speed and exhaust gas colour, adjusting valve clearance, measuring compression and blow-by pressure, testing and adjusting fuel injection timing, measuring engine oil pressure, adjusting the engine stop solenoid and fuel control linkage, engine speed sensor setting, hydraulic pressure testing for work equipment, swing and travel circuits, LS differential pressure measurement and LS valve adjustment, PC valve adjustment, TVC-EPC solenoid output pressure, control circuit pressure, PPC valve output pressure, solenoid valve output pressure, work equipment and swing PPC valve adjustment, travel deviation testing and correction, oil leakage testing for swing and travel motors, releasing residual hydraulic pressure, swing circle bearing clearance, track shoe tension, bleeding air from each hydraulic circuit, potentiometer replacement and diode testing. The remainder is the troubleshooting suite, organised by mode: engine (S), communication (N), controller governor control (E), controller pump control (C), input signal (F), hydraulic and mechanical (H), and machine monitor (M).

30 Disassembly and Assembly

Step-by-step removal, disassembly, assembly and installation procedures with torque values, shim notes and special tool references. Components covered: counterweight, injection pump, cylinder head, main pump, control pump, engine and main pump assembly, hydraulic oil cooler, radiator, swing motor and swing machinery, swing motor alone, centre swivel joint, control valve, work equipment PPC valve, travel PPC valve, hydraulic tank, fuel tank, controller, monitor panel, air conditioner unit, operator’s cab, floor frame, revolving frame, swing circle, work equipment, swing bracket, steel shoe / rubber pad shoe / road liner, rubber shoe, final drive, idler, recoil spring, track roller and the boom, arm, bucket, boom swing and blade cylinders. Opening warnings, blind plug part numbers, coating materials and standard tightening torques are all included.

90 Others

Hydraulic circuit diagrams for the STD spec and EU spec machine, plus electrical circuit diagrams in two halves for STD and EU spec. These are the diagrams to trace a circuit, confirm a connector pin, or check which line feeds which actuator before reaching for a spanner.

What You Can Do With This PC78MR-6 Shop Manual

This is the reference to reach for when the machine goes down or when a repair has to be right the first time. With it in hand you can:

• Read the relief and unload pressures and know whether a pump, valve or relief is out of spec — the control valve set pressures are 26.5 MPa (270 kg/cm²) for work equipment and travel, 21.1 MPa (215 kg/cm²) for swing and blade, and 3.1 MPa (32 kg/cm²) for control.
• Diagnose hydraulic drift, low boom, arm or bucket speed, slow swing, weak travel, travel deviation, boom swing cushion problems, TVC-EPC faults and the specific user and service codes the controller sets, including E02, E03, E05, E40 and E41 groups.
• Set up the LS valve, PC valve, control relief valve and PPC valve output pressures with the actual adjustment quantity per turn of the screw.
• Pull and reinstall the main pump, control valve, swing motor and swing machinery, centre swivel joint, final drive, idler, track roller and hydraulic cylinders to the correct torque with the right shims and blind plugs.
• Judge wear against the maintenance standard: idler guide width, recoil spring free and installed length, track roller tread thickness, shoe grouser height, bushing and pin interference, sprocket root and tip wear, swing circle bearing clearance, cylinder-to-bushing clearance and more.
• Trace an electrical fault using the connector arrangement diagram, connector pin tables and T-adapter part numbers, and the M mode troubleshooting for the monitor panel, gauge and sensor circuits.
• Do the routine work correctly — track shoe tension, oil and coolant capacities, air bleeding, valve clearance, injection timing, engine stop solenoid and fuel control linkage adjustment.

The PC78MR-6 is a compact, tight-radius machine working in jobsites where a slow hydraulic fault or a wrongly torqued component shows up directly as downtime. The numbers in this manual — the 26.5 MPa relief setting, the 245–309 Nm swing circle bolt torque, the 0.75–1.00 mm engine speed sensor clearance, the 150 mm per turn travel deviation adjustment — are the difference between a repair that holds and one that comes back. Guessing on an excavator is expensive; this manual takes the guesswork out.

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This Komatsu PC78MR-6 shop manual (SEBM030601) is delivered as an instant download after checkout — no shipping wait, no paper volume to lose in the workshop. Open it on a laptop, tablet or phone, use it as a searchable reference, and print only the pages you need for the job in front of you. Whether you are a PC78MR-6 owner, an independent mechanic, or a workshop technician supporting a fleet of Komatsu excavators, this single PDF is the full service, testing and repair reference in one file.