Komatsu PC78MR-6 Excavator & S4D95LE-3-A Engine - Official Service & Repair Guide 2004 Edition

Komatsu PC78MR-6 Service & Repair Manual - 2004

Maintain your fleet with factory-level precision and minimize operational downtime. This professional-grade workshop manual provides the definitive technical framework required for the complete maintenance, diagnostic troubleshooting, and structural overhaul of the Komatsu PC78MR-6 hydraulic excavator.

Model Coverage & Hardware Details:

• Manufacturer Model: Komatsu PC78MR-6 (2004)
• Engine Configuration: Komatsu S4D95LE-3-A
• Engine Specs: 4-cycle, water-cooled, in-line, direct injection diesel.
• Displacement: 3.26 Liters (3,260 cc).
• Rated Output: 40.5 kW (54.0 HP) @ 1,850 rpm.

Professional Benefits:

• Operational Safety: Follows strict Komatsu safety protocols for high-pressure hydraulic discharge and heavy component hoisting.
• Technical Accuracy: Features verbatim factory tightening torques and wear limits to prevent premature component failure.
• Efficient Troubleshooting: Includes integrated diagnostic charts correlating machine symptoms with mechanical and electrical causes.
• Precision Engineering: Detailed service standards for the swing circle, track frame, and hydraulic pumps ensure factory-spec performance.

What’s Included in This Service Manual Set:

• Digital Chassis & Engine Volume: Full technical coverage for the Komatsu PC78MR-6 (Form No. SEBM030602).
• Scope: General Specifications, Structure and Function, Testing and Adjusting, Disassembly and Assembly, and Maintenance Standards.
• Specialized Content: Dedicated sections for the CLSS (Closed-center Load Sensing System) and Electronic Control Systems.

TECHNICAL DATA & STRUCTURE

Technical Identification & Specifications

• Serial Number Locations: The Machine Model and Serial Number (1001 and up) are located on the primary identification plate, typically found on the front right of the revolving frame or cab pillar. The Engine Serial Number is located on the S4D95LE-3-A engine block.
• Factory Specifications (Proof of Depth):
  • Main Relief Valve Set Pressure: 26.5 ± 0.98 MPa (270 ± 10 kg/cm²).
  • Swing Circle Bolt Torque: 245 – 309 Nm (25 – 31.5 kgm).
  • Main Pump Discharge (P1+P2): 80 x 2 + 60 + 12.7 l/min.
  • Cylinder Head Tightening: Angle tightening method (mark and rotate 90° ± 30° after initial torque stages).
  • Control Circuit Relief Pressure: 3.14 MPa (32 kg/cm²).

Visual & Diagnostic Features

• Integrated Schematics: Includes high-resolution Hydraulic Circuit Diagrams (Standard, EU, and Norway specs) and Electrical Circuit Diagrams.
• Exploded Views: Detailed sectional views for the Hydraulic Pump (LPD45+45), Control Valve (9-spool type), and Final Drive components.
• Diagnostic Tools: Features "Bit Pattern" monitoring tables for the monitor panel and T-adapter connection tables for sensor testing.
• Troubleshooting Flowcharts: Specialized diagnostic paths for engine performance, hydraulic drift, and travel deviation.

Contents at a Glance

• 01 General: Dimensions, weight tables, and lubrication charts.
• 10 Structure, Function & Maintenance Standard: Deep dive into PTO, CLSS, and undercarriage tolerances.
• 20 Testing and Adjusting: Performance testing, relief valve adjustments, and fuel control linkage calibration.
• 30 Disassembly and Assembly: Step-by-step removal/installation procedures for the engine, main pump, and cylinders.
• 90 Others: Specialized circuit diagrams and attachment specifications.

Professional Value

This documentation provides the factory-stipulated "Wear Limits" and "Service Standards" (e.g., standard clearance for the swing circle bearing axial play: 0.20–0.80 mm). By utilizing these exact tolerance tables, technicians can make informed "repair vs. replace" decisions, ensuring maximum component longevity and preventing catastrophic machine failure.