Part of the Doosan Repair Manuals.
Need factory-level data for your Doosan DX255LC-3 excavator? This 874-page Doosan DX255LC-3 shop manual PDF (OEM #950106-00374E) covers everything from the swing bearing to the track assembly, and its procedures carry over to the DX140LC-3, 180LC-3, 225LC-3, and 300LC-3. Inside: complete hydraulic schematics, electrical wiring diagrams, and a dedicated troubleshooting, testing, and adjustment section spanning pilot pressure, the power mode valve, and pump input power control. You also get step-by-step teardown and reassembly for the main pump, swing device, travel device, cylinders, and center joint, backed by standard torque tables. Set track tension to 320-340 mm on normal ground, stretch it to 340-370 mm in mud or snow, and keep a 27 mm socket handy for the grease valve. Your machine is down; get factory numbers, not forum guesses. Bookmarked with a live text layer: jump to any section or type the spec you need.
What's Inside This Doosan DX255LC-3 Manual
| System | Pages | Key Topics |
|---|---|---|
| Safety | 5-72 | Track Excavator Maintenance Safety |
| Specifications | 73-102 | Specifications for DX255LC-3 |
| General Maintenance | 103-140 | Standard Torques |
| Upper Structure | 141-202 | Cabin, Counterweight, Fuel Tank, Fuel Transfer Pump, Swing Bearing |
| Lower Structure and Chassis | 203-236 | Track Assembly |
| Engine and Drivetrain | 237-266 | Engine Coolant Heater, Drive Coupling |
| Hydraulic System Troubleshooting, Testing and Adjustment | 267-302 | Troubleshooting, Pilot Pressure, Power Mode Valve, Pressure Up Valve, Pump Input Power Control |
| Accumulator | 303-310 | Gas-Charged Storage, Precharge Pressure, Diaphragm, Specifications |
| Center Joint (Swivel) | 311-324 | Inspection, Testing, Disassembly, Reassembly, Slipper Seal |
| Cylinders | 325-362 | Theory of Operation, Disassembly, Reassembly, Piston Jig, Dust Wiper Jig, Slipper Seal Straightening Jig |
| Swing Device | 363-414 | Swing Bearing, Reduction Gear, Reactionless Valve, Brake Part, Maintenance Standards |
| Travel Device | 415-472 | Operation Manual, Disassembly, Reassembly, Performance Check Test, Seal Information |
| Main Pump | 473-518 | Axial Piston Pump, Regulator, Disassembly, Reassembly, Flow Control |
| Gear Pump, Main Control Valve, Breaker EPPR Valve, Hydraulic Schematic | 519-682 | - |
| Electrical System | 683-848 | Electrical Supply System, Engine Starting Circuit, Engine Preheating System, Charging System, Monitoring System, Graphic Information Area Display, User Menu, Special Menu |
| Attachments | 849-874 | Boom and Arm, Bucket |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Thermal limiter open temperature | 150 ±5°C (302 ±41°F) | p. 190 |
| Thermal limiter reactivation temperature | 143°C (289°F) | p. 190 |
| Recommended track tension distance for Normal terrain | 320 - 340 mm (12.60 - 13.39 in) | p. 212 |
| Recommended track tension distance for Muddy, Sandy or Snowy terrain | 340 - 370 mm (13.39 - 14.57 in) | p. 212 |
| Tightening Torque for M6 Hex Bolt | 120 ±20 kg•cm | p. 388 |
| Tightening Torque for M10 Hex Socket Head Bolt | 300 ±50 kg•cm | p. 388 |
| Fuel filter replacement period | 500 hr | p. 719 |
| Pilot filter replacement period | 1,000 hr | p. 719 |
| Return filter replacement period | 1,000 hr | p. 719 |
| Engine oil filter replacement period | 500 hr | p. 719 |
| Main Relief Pressure (Normal) | 330 kg/cm2 | p. 96 |
| Main Relief Pressure (Pressure Up) | 350 kg/cm2 | p. 96 |
Doosan DX255LC-3 Common Problems This Manual Covers
Doosan DX255LC-3 hydraulic functions slow and weak, pump noisy under load, boom struggles to lift full bucket
Check hydraulic oil level first — running low causes the cavitation noise you are hearing. Verify main relief pressure against the 330 kg/cm2 (4,693 psi) normal-operation spec on page 96 (350 kg/cm2 with Pressure Up), then work the boom, arm and bucket circuit checks starting on page 267. Replace the return filter if it is past the interval in the maintenance chart.
Manual Section: Hydraulic System Troubleshooting, Testing and Adjustment p. 267Engine cranks but won't start, needs repeated priming after running low on fuel
Check for air in the fuel lines before condemning the lift pump. Replace the fuel filter if it is near its 500 hour change interval on page 719, then prime until fuel flows free of bubbles. Inspect the fuel transfer pump and suction lines using the Upper Structure procedures starting on page 141, and clean battery ground connections.
Manual Section: Upper Structure p. 141Track tension keeps loosening after a few shifts, undercarriage rattles and track sags between rollers
Measure track sag and set it to 320 to 340 mm for normal terrain, or 340 to 370 mm for mud, sand, or snow, per the spec on page 212. Add grease through the adjuster valve with a 27 mm socket to tighten; crack the valve slowly to release. Inspect pins and bushings for wear while you are under there.
Manual Section: Lower Structure and Chassis p. 212Swing motor groans and jerks starting a swing, upper structure drifts when parked on slopes
Check swing reduction gear oil level and pull a drain sample; metal flake means bearing or gear wear. Test the reactionless valve and brake following the Swing Device procedures starting on page 363. When reassembling the motor, torque M20 hex socket head bolts to 4,400 ±660 kg•cm per the chart on page 388.
Manual Section: Swing Device p. 363Coolant temperature climbs under load and engine power drops until the machine idles down
Clean the radiator and oil cooler cores with compressed air, blowing opposite to normal airflow. Check coolant level cold and inspect the fan belt for glazing or cracks. Verify the water pump and thermostat using the Engine and Drivetrain section starting on page 237, and rule out fuel starvation from a filter past its 500 hour interval.
Manual Section: Engine and Drivetrain p. 237Frequently Asked Questions
How do I reset the operation hour or change the replacement period for filters and oil?
To reset the operation hour or change the replacement period, use the jog switch to locate the cursor on the desired item. Click the jog switch to display the selection screen, then select the operation hour reset or change the replacement period. Turn the jog switch to select 'YES' and click to confirm the reset. p. 718
What are the replacement specifications for the Fuel filter?
The basic setup value for the fuel filter replacement period is 500 hours, with a minimum available setup value of 100 hours and a change value step of 50 hours. p. 719
What is the tightening torque for the main relief valve on the main control valve?
The tightening torque for the main relief valve is 7.95 - 8.97 kg•m (58 - 65 ft lb). p. 591
How do I troubleshoot the E003464 fault code on the Doosan DX255LC-3?
The E003464 fault code indicates a throttle valve control issue. The display code shows the DC motor is unpowered or the position angle is 89 degrees with a voltage of 14.25% +/- 3.5% (0.713 V). p. 764
What is the standard torque for an M16 hex bolt (Grade 10.9) used on the machine?
The standard tightening torque for an M16 hex bolt (Grade 10.9) is 26.0 kg•m (188.05 ft lb). p. 130
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