Komatsu PC27MRX–PC45MRX Excavator Shop Manual (P/N SEBM016808)

• Covers Komatsu PC27MRX-1 through PC45MRX-1 excavators in canopy and cab configurations: PC27MRX-1 serial 11574 and up, PC30MRX-1 10001 and up, PC35MRX-1 3930 and up, PC40MRX-1 1001 and up, and PC45MRX-1 1001 and up.
• Komatsu factory shop manual publication SEBM016808, printed 08-03(02); the supplied PDF contains 947 pages.
• Organized around factory Structure and Function, Testing and Adjusting, Troubleshooting, Disassembly and Assembly, Maintenance Standard, hydraulic-circuit, electrical-circuit, torque, lubricant, and component-weight data.

This manual is built around the actual MRX-1 machine systems rather than generic excavator service information. Engine coverage distinguishes the 3D82AE-3 family used on the PC27MRX-1, the 3D84E-3 family used on the PC30MRX-1 and PC35MRX-1, and the 4D84E-3/4D88E-3 families used on the PC40MRX-1 and PC45MRX-1. The PC30MRX-1 specification, for example, identifies the 3D84E-3K at 1,496 cc. PC40 specifications are split at serial 5501 and PC45 specifications at serial 3001 in several engine, hydraulic, and control-system sections, so these later machines are not treated as one unchanged build. Work-equipment performance tables also distinguish canopy from cab/TOPS configurations where the factory values differ.

Hydraulic, Drive, and Diagnostic Coverage

The hydraulic chapters explain the CLSS (Closed Center Load Sensing System), including the variable-displacement piston pump, PC and LS valves, servo piston, pressure-compensation valves, unload valve, main relief system, PPC controls, solenoid valves, center swivel joint, travel motors, and swing motor/brake circuit. The standard-value tables are model-specific: work-equipment/travel relief pressure is 22.06 ± 0.49 MPa on PC27MRX-1, 25.5 ± 0.49 MPa on PC30MRX-1, and 26.3 ± 0.49 MPa on PC35MRX-1/PC40MRX-1/PC45MRX-1. That model distinction matters when pressure testing or making repair decisions.

Swing-system data is equally configuration-specific. The LMF16 swing motor is listed at a rated 1,165 rpm for PC27MRX-1/PC30MRX-1, 1,266 rpm for PC35MRX-1, and 1,820 rpm for PC40MRX-1/PC45MRX-1. Swing machinery oil capacity is approximately 0.9 L on PC27/30/35 and 1.3 L on PC40/45. Maintenance-standard tables go beyond nominal specifications with backlash, bearing-clearance, wear, and repair-limit data for the swing machinery, swing circle, track frame, idlers, carrier and track rollers, sprockets, track shoes, center swivel joint, hydraulic cylinders, and work-equipment pins and bushings.

The General section also provides model-by-model lubricant and water tables with specified-versus-refill capacities, along with an electric wire-code chart covering conductor size, current rating, circuit classification, and color coding.

Factory procedures include engine-speed and exhaust-smoke checks, valve-clearance adjustment, compression and engine-oil-pressure testing, fuel-injection timing, track-tension and sprocket-wear checks, hydraulic relief and LS differential-pressure testing, PC-valve adjustment, PPC/solenoid output testing, swing holding-brake checks, travel-deviation testing, cylinder internal-leakage checks, hydraulic air bleeding, breaker service-valve testing, and hydraulic-breaker N2 pressure charging. The repair sections also cover removal, installation, disassembly, and assembly of the engine/main-pump package, center swivel joint, travel motor, swing motor and swing machinery, swing circle, idler/recoil components, hydraulic cylinders, solenoid/PPC assemblies, and major work-equipment structures.

The special-tool lists identify factory tooling by part number instead of leaving critical repair equipment generic. Examples include the 790-501-5200 unit repair stand and 790-101-5001 push-tool kit for hydraulic-pump work, plus the 799-101-5130 gauge and 799-101-5160 nipple among the tooling used for swing-motor brake and turning-torque work.

Schematics, Electrical Fault Finding, and Repair Detail

Representative drawings include the CLSS “Hydraulic Circuit Diagram and Name of Valve,” “Hydraulic Circuit Diagram,” “Electrical Circuit Diagram — Cab Specification,” “Actual Electric Wiring Diagram,” “Air Conditioner Piping,” and “Machine Monitor System.” Electrical troubleshooting follows real failure modes such as an engine that will not stop, a work-equipment lock that does not hold, or travel speed that will not increase, with connector, resistance, voltage, solenoid, relay, and harness checks tied to the related circuit diagrams. Hydraulic troubleshooting addresses poor fine control, low power, hydraulic drift, travel deviation, swing overrun, pump noise, steering problems, and travel-speed switching.

Several manual-specific details matter during a real repair. The swing-motor hydraulic timer delays brake application because sudden brake engagement can damage motor components. The PHV-500 travel-motor section warns that contamination between precision parts can cause seizure. During PC40/45 engine/main-pump removal, Komatsu specifically cautions against damaging the radiator core while the assembly is being lifted.

One scope limit is important before purchase: this publication includes machine-side engine testing, adjustment, cylinder-head work, and engine/main-pump removal, but directs the technician to the separate 68E-88E Series Engine Shop Manual for detailed engine service. In drawings, PC27MR/PC30MR/PC35MR/PC40MR/PC45MR are stated to be the same model designations as the corresponding MRX machines.

Because these excavators use high-pressure hydraulic circuits and heavy assemblies, follow the manual’s specified pressure-release, blocking, lifting, and battery-isolation precautions before beginning service.