2004 Komatsu PC78MR-6 Hydraulic Excavator Shop Manual (P/N SEBM030602)

This Komatsu PC78MR-6 shop manual is OEM publication SEBM030602, printed in Japan in May 2004. It covers machines with serial numbers 1001 and up, including the S4D95LE-3-A engine installation, chassis, hydraulic equipment, and electrical controls.

• Engine testing and service: Fuel injection timing, valve clearance adjustment, compression and blow-by checks, plus removal and installation of the injection pump and cylinder head.

• Hydraulic diagnostics: Pressure tests, PC and LS valve adjustments, PPC and EPC checks, travel and swing motor leakage tests, drift diagnosis, and air bleeding.

• Undercarriage and swing: Maintenance standards for track frames, idlers, and rollers, with coverage for steel shoes, road liners, and rubber shoes.

• Component repair: Disassembly and assembly procedures for swing machinery, the center swivel joint, recoil springs, track rollers, and hydraulic cylinders.

• Electrical troubleshooting: Engine and pump control fault charts, monitor diagnostics, connector pin tables, and boom swing potentiometer checks and correction.

• Drawings and schematics: Component sectional views, specification dimensions, working ranges, hydraulic circuit diagrams, and electrical wiring diagrams for documented regional configurations.

Written for service technicians and repair workshops, the procedures assume suitable lifting equipment, hydraulic test instruments, and specified service tools.

Engine service and scope

Engine coverage includes machine-level testing, fuel control linkage checks, and engine removal and installation. Detailed internal engine work is referred to the separate 95-3 Series Engine Shop Manual, which is not included in this PDF.

The engine stop solenoid adjustment includes a warning about premature linkage connection: restricted solenoid travel can leave the operating current flowing and burn the coil.

CLSS and hydraulic fault isolation

CLSS (Closed-center Load Sensing System) explanations connect pump control with pressure compensation, unloading, and combined actuator operation. Sectional drawings identify the hydraulic pump, control valve, travel motor, and swing motor components.

The hydraulic drift check distinguishes leakage at the cylinder packing from leakage through the control valve, helping technicians identify the repair area before dismantling components.

Separate sections explain the PPC lock solenoid valve and other solenoid controls. The air bleeding guidance warns that running the pump without oil in its case can cause overheating and damage.

Configuration differences and workshop references

Solenoid valve arrangements and controller connections change at serial number 1095. The EU boom hydraulic anti-burst valve has separate coverage for serial numbers 1001–1189 and 1190 and up.

The optional multi-control valve is documented with its control patterns; brake accumulator information applies where equipped. Optional air conditioner coverage includes piping and unit removal and installation.

Power train layouts and undercarriage wear limits accompany the component procedures. Standard tightening torque tables cover metric bolts, flared nuts, split flange bolts, and O-ring boss piping joints.

Hydraulic diagrams distinguish standard and EU machines, while electrical circuit diagrams cover standard, EU, and Norway specifications. Connector location drawings and monitor service functions support tracing faults through the electric control system.

Safety notes address residual hydraulic pressure, supported work equipment, and heavy component handling.

Technical preview: relief pressures and fluid capacities

The following pressures and capacities are a small selection of the manual’s hydraulic and cooling reference data.

The CLSS component list specifies 26.5 MPa (270 kg/cm²) for the main relief valve and 21.1 MPa (215 kg/cm²) for the gear pump relief valve. Individual testing tables provide the relevant operating conditions and tolerances.

Fluid tables list 120 L for the hydraulic system’s specified capacity and 10.5 L for the cooling system. The separate hydraulic tank specification gives a tank volume of 80 L.

PDF search, navigation, and file contents

Search and diagram navigation: Main text is searchable, and embedded bookmarks link to chapters and many subsections. Labels in the end-of-manual circuit diagrams are not text-searchable; small wire, connector, and terminal labels require zooming for comfortable reading.

Supplied as one printable English-language PDF with 583 pages, including the cover, three revision-list pages, and 12 blank separator pages. All are included in the stated page total.