2003–2008 Komatsu PC27MR-2, PC30MR-2, PC35MR-2, PC40MR-2 & PC50MR-2 Excavator Shop Manual (P/N SEBM032406)

Komatsu shop manual SEBM032406, dated January 2005, covers the 2003–2008 PC27MR-2, PC30MR-2, PC35MR-2, PC40MR-2, and PC50MR-2 hydraulic excavators in canopy and cab configurations.

Supplied as one 623-page PDF.

• Engine and cooling: Compression and oil-pressure testing, valve-clearance and injection-timing adjustment, plus removal and installation of the engine, injection pump, radiator, and hydraulic oil cooler.

• CLSS hydraulics: LS differential-pressure testing, PC/PPC valve adjustment, cylinder-leakage checks, hydraulic bleeding, and swing holding-brake release-pressure measurement.

• Swing and undercarriage repair: Center swivel joint and swing machinery disassembly and assembly, recoil spring service, track shoe replacement, and roller assembly procedures.

• Electrical and monitor diagnosis: E-mode and M-mode troubleshooting charts, starting and stopping circuits, PPC lock checks, connector pin tables, and sensor testing.

• Cab and air conditioning: Floor-tilting procedures, air conditioner troubleshooting and unit replacement, bonded cab glass replacement, and front window assembly removal.

• Diagrams and service standards: Model-specific hydraulic and electrical circuit diagrams, hydraulic components layout drawings, working range drawings, and component-specific maintenance standards.

Written for service technicians performing workshop repairs, this manual calls for the specified measuring equipment, lifting gear, and special tools for the relevant jobs.

Engine Testing and Fuel-System Service

The engine specifications distinguish these configurations:

S-mode troubleshooting covers hard starting, hunting, low power, abnormal exhaust smoke, overheating, and oil contamination. Fuel-pump replacement guidance uses the pump's recorded injection angle and identifies adjustment seal YM158090-51990.

Engine coverage includes removal with the hydraulic pump assembly, but does not extend to a full internal engine overhaul.

CLSS Hydraulics and Swing Repair

The construction and function sections cover the hydraulic powertrain and CLSS pressure compensation. They also explain multi-control valves, the hydraulic tank's cyclone assembly, and travel-motor counterbalance and parking-brake circuits.

Pump and pilot-supply arrangements differ by model. The PC40/50MR-2 drawings include the pump configuration for air-conditioned machines and a separate additional-attachment hydraulic circuit.

Fault isolation: H-mode charts connect whole-machine weakness, slow individual cylinders, and travel/blade faults with different pressure checks, helping narrow the suspect circuit before component removal.

Center swivel joint: The PC27/30/35MR-2 arrangement uses seven slipper seals and a backup ring; PC40/50MR-2 uses eight slipper seals. The repair notes flag the risk of damaging slipper seals and the O-ring during rotor installation.

Procedure limits: The hydraulic-cylinder section provides assembly procedures only. The control-valve repair section contains assembly precautions, supported by the structure, function, and maintenance-standard drawings.

Electrical Fault Tracing

Connector arrangement diagrams distinguish canopy and cab wiring, with pin-number connection tables and T-adapter references for electrical testing. Wiring diagrams, wire codes, and electrical test values support checks of the harnesses, relays, and switches.

The electronic monitor system has separate diagnostic coverage for warning indications, the alarm buzzer, preheating, coolant and fuel gauges, the service meter, and second travel speed selection.

Undercarriage and Cab Service

Undercarriage data distinguishes rubber tracks, double-grouser steel shoes, and triple-grouser steel shoes. Recoil spring procedures identify different rubber-shoe and steel/road-liner configurations on PC40/50MR-2.

The idler, track roller, and carrier roller procedure sections cover assembly only, with related bushing, bearing, and seal information. A separate test procedure covers swing-circle bearing clearance.

For bonded cab glass, the manual warns that scratching the painted mounting surfaces during adhesive removal reduces adhesion. The front-window section explains the assembly removal required for glass replacement.

Technical Reference and Repair Specifications

Standard value tables provide factory reference values and service limits. Reference data includes bolt, nut, and flared-nut torque tables; engine oil, coolant, and hydraulic fluid capacities; and piston-rod/bushing clearance limits for the boom, arm, bucket, boom swing, and blade cylinders.

Specification dimension drawings supplement the working range drawings. Special-tool lists identify equipment such as differential-pressure gauge 799-401-2701 and cylinder repair stand 790-502-1003.

Working on pressurized hydraulic lines and heavy chassis components carries inherent physical risks.

PDF Navigation and Diagram Readability

The total comprises 622 manual pages, including the factory cover, three revision-list pages, and nine blank pages, plus one dealer banner page. Text search is partial: the safety/foreword pages and circuit-diagram labels are not searchable, while embedded bookmarks provide chapter and procedure navigation. Small schematic labels require zooming.