Whether you are checking HST oil pressure this afternoon or splitting a final drive, the Komatsu D39EX-21, D39PX-21 shop manual PDF (Komatsu SEBM023810, 464 pages) puts the factory procedures for both bulldozer variants on the bench beside you. Troubleshooting fills roughly a third of the book. It is split into electrical, hydraulic and mechanical, machine monitor, and engine sections that take each fault from symptom to failed component. Full hydraulic and electrical circuit diagrams close out the manual, so you can trace PPC lines and the HST loop from pump to travel motor, and standard value tables give you blow-by, relief pressure, and valve clearance targets. When bleeding a work equipment cylinder, stop it 100 mm short of stroke end for the first 4 to 5 cycles; Nominal No. 03 and 04 O-ring boss joints take 84 to 132 Nm. Blade drift rarely announces its own cause. Your bookmarked, text-searchable copy goes wherever the dozer is parked.
What's Inside This Komatsu D39EX-21, D39PX-21 Manual
| System | Pages | Key Topics |
|---|
| General | 35-43 | Specification Drawing, Specifications, Weight Table |
| Structure and Function, Maintenance Standard | 44-171 | Cooling System, HST Pump, HST Motor, Control Valve |
| Standard Value Tables | 172-180 | Engine Standard Values, Chassis Standard Values, Electrical System Standard Values |
| Testing and Adjusting Procedures (Engine) | 181-197 | Engine Speed, Exhaust Color, Blow-By Pressure, Valve Clearance, Fuel Injection Timing, Compression Pressure |
| Testing and Adjusting Procedures (Chassis) | 198-225 | Air Conditioner Compressor Belt, HST Oil Pressure, Solenoid Valve Output Pressure, Work Equipment Main Relief Pressure, PPC Valve Output Pressure, Parking Brake Release |
| Troubleshooting (General and Electrical) | 226-312 | Troubleshooting Points, Electrical System Troubleshooting, Starting Motor, Headlamp, Air Conditioner, Backup Alarm, Horn |
| Troubleshooting (Hydraulic and Mechanical) | 313-329 | Travel System, Work Equipment, Hydraulic Drift, HST Noise, Engine Stalls |
| Troubleshooting (Machine Monitor System) | 330-347 | Monitor Panel, Preheating Caution Lamp, HST Oil Temperature Gauge, Engine Water Temperature Gauge, Fuel Level Gauge, Service Meter |
| Troubleshooting (Engine System) | 348-371 | Starting Performance, Engine Rotation, Exhaust Smoke, Oil Consumption, Coolant Temperature, Abnormal Noise, Vibration |
| Disassembly and Assembly | 372-457 | Fuel Injection Pump Assembly, Cylinder Head Assembly, Travel Motor and Final Drive Assembly, Main Control Valve Assembly |
| Others | 458-464 | Hydraulic Circuit Diagram, Electrical Circuit Diagram |
Quick Reference Specifications
| Specification | Value | Page |
|---|
| Tightening torque for O-ring boss piping joints (Nominal No. 02) | 35 – 63 Nm | p. 22 |
| Tightening torque for O-ring boss piping joints (Nominal No. 03, 04) | 84 – 132 Nm | p. 26 |
| Tightening torque for 102, 107 and 114 engine series (Taper screws 1/16 inch) | 3 ± 1 Nm | p. 28 |
| Tightening torque for 102, 107 and 114 engine series (Taper screws 1/8 inch) | 8 ± 2 Nm | p. 28 |
| Engine oil pan capacity (Specified) | 14 L | p. 43 |
| Engine oil pan capacity (Refill) | 12.5 L | p. 43 |
| Alternator voltage | 27.5–29.5V | p. 180 |
| Oil pressure gauge range | 1 MPa {10 kg/cm2} | p. 194 |
| Final drive case oil capacity | 3.91 L | p. 409 |
| Mounting bolt torque | 98 – 123 Nm | p. 408 |
