As a core piece of equipment in construction projects, excavator faults can affect both efficiency and safety. The following outlines common faults and solutions across six core modules: engine system, hydraulic system, electrical system, transmission system, working devices, and travel devices.

1. Common Engine System Faults

1.1 Engine Won’t Start
Fault Causes:

• Insufficient battery power or loose connections.

• Fuel system blockage (dirty filter, air in the fuel line).

• Starter motor or ignition switch failure.

• Insufficient cylinder compression (worn piston rings, poor valve sealing).

Solution:

• Check battery voltage, clean and tighten the terminals; jump-start if necessary.

• Replace fuel filter and bleed air from the fuel system (manual fuel pump).

• Test the starter motor solenoid and replace damaged components.

• Check cylinder pressure, repair or replace piston rings and valve components.

1.2 Engine Lacks Power
Fault Causes:

• Clogged air filter, insufficient intake.

• Fuel injection system failure (poor atomization of injectors, low fuel pump pressure).

• Damaged turbocharger, reduced boosting effect.

• Engine overheating, insufficient coolant, or cooling fan failure.

Solution:

• Clean or replace the air filter, check intake pipes for leaks.

• Calibrate injectors, check fuel pump pressure, and replace parts if necessary.

• Repair turbocharger, replace damaged bearings or impellers.

• Check coolant level, clean the radiator, and repair or replace the fan clutch.

1.3 Abnormal Engine Noises
Fault Causes:

• Worn crankshaft or connecting rod bearings causing knocking sounds.

• Excessive valve clearance causing tapping sounds.

• Slipping belt or damaged tensioner causing friction sounds.

• Damaged water pump or alternator bearings.

Solution:

• Disassemble engine, replace worn bearings, and adjust clearances.

• Adjust valve clearance to standard values (refer to manual).

• Replace aging belts, repair the tensioner bearings.

• Replace damaged water pump or alternator assemblies.

2. Common Hydraulic System Faults

2.1 Hydraulic Oil Leaks
Fault Causes:

• Loose hose connections, aging or damaged seals.

• Scored piston rods causing oil seal leaks.

• Hydraulic pump or valve group seal failure.

Solution:

• Tighten connections, replace O-rings or combined seals.

• Polish piston rods and replace cylinder seals.

• Disassemble hydraulic pump or valve group, replace worn seals, and grind valve plates if necessary.

2.2 Hydraulic Motion Weak or Slow
Fault Causes:

• Insufficient or contaminated hydraulic oil (reduced viscosity, mixed with impurities).

• Worn hydraulic pump, insufficient output pressure.

• Low safety valve or relief valve set pressure, or stuck valve spool.

• Internal leakage in the cylinder (damaged piston seals).

Solution:

• Check oil level, replace hydraulic oil and filter, clean the oil tank.

• Test hydraulic pump outlet pressure, replace worn pump or plunger assembly.

• Calibrate safety valve pressure (refer to manufacturer standards), clean valve spool and check for scoring.

• Disassemble cylinder, replace piston seals, and check cylinder wall wear.

2.3 Hydraulic System Overheating
Fault Causes:

• Clogged hydraulic oil cooler, poor heat dissipation.

• Hydraulic oil viscosity not suitable for operating conditions (using low-viscosity oil in high-temperature environments).

• Faulty unloading valve causing continuous high-pressure circulation of hydraulic oil.

Solution:

• Clean radiator surface and debris, check fan operation.

• Replace hydraulic oil with one suitable for the operating conditions (e.g., high-viscosity anti-wear oil in summer).

• Repair unloading valve, replace stuck or worn valve spools.

3. Common Electrical System Faults

3.1 No Power or Partial Electrical Failures
Fault Causes:

• Battery switch not turned on, or blown fuse.

• Oxidation, loose, or shorted wiring connections.

• Faulty relay or control module (ECU).

Solution:

• Check the battery switch, replace the blown fuse (ensure correct specification).

• Clean wiring connections, reconnect, and fix shorted or open circuits.

• Use a multimeter to check relay coils and contacts, replace damaged relay or ECU.

3.2 Instrument Panel Display Abnormalities or Alarms
Fault Causes:

• Sensor failure (e.g., coolant temperature sensor, oil pressure sensor).

• Poor contact in the instrument panel's internal circuit.

• Actual engine or hydraulic system faults triggering alarms (e.g., overheating, low pressure).

Solution:

• Use a diagnostic tool to read fault codes, replace defective sensors (e.g., coolant temperature sensor, oil pressure switch).

• Disassemble the instrument panel, repair poor solder joints or replace the circuit board.

• First, address actual engine/hydraulic faults, then clear alarm signals.

3.3 Lighting System Failure (e.g., Headlights not working)
Fault Causes:

• Burnt-out bulb or poor contact in the lamp socket.

• Faulty light switch or relay.

• Broken circuit or blown fuse.

Solution:

• Replace with the same specification bulb, clean lamp socket contacts.

• Short-circuit the relay to test lighting, replace damaged switch or relay.

• Use a tester to check the circuit, repair break points, and replace the fuse.

4. Common Transmission System Faults

4.1 Transmission Noise or Difficulty Shifting
Fault Causes:

• Low or contaminated transmission oil, worn gears.

• Slipping or incomplete clutch disengagement (mechanical transmission).

• Faulty shift solenoid (electronically controlled transmission).

Solution:

• Check oil level, replace transmission oil and filter, disassemble the gearbox to replace worn gears.

• Adjust clutch pedal free play, replace clutch disc or pressure plate.

• Use a diagnostic tool to check solenoid signals, replace faulty solenoids.

4.2 Drive Axle Leaks or Overheating
Fault Causes:

• Damaged main reduction or differential oil seals.

• Insufficient or incorrect gear oil, leading to poor lubrication.

• Worn bearings causing abnormal friction.

Solution:

• Replace drive axle oil seals, clean the leaking area.

• Add or replace the correct gear oil (e.g., GL-5 85W-90).

• Disassemble drive axle, replace worn bearings, and adjust gear meshing clearance.

5. Common Working Device Faults (Bucket, Boom, Arm)

5.1 Stiff Movements or Inability to Operate
Fault Causes:

• Worn pins or bushings, causing excessive play and jamming.

• Bent piston rods or deformed cylinders.

• Sticking or malfunctioning multi-way valve spool, or pressure compensator valve failure.

Solution:

• Replace worn pins and bushings, apply grease (regular lubrication according to schedule).

• Straighten piston rods or replace cylinder assemblies.

• Disassemble multi-way valve, clean valve spool, replace damaged springs or valve seats.

5.2 Insufficient Digging Force in Bucket
Fault Causes:

• Internal leakage of cylinder piston seals, causing pressure loss.

• Deformed linkages or rocker arm mechanisms, reducing transmission efficiency.

• Insufficient hydraulic system pressure (same causes as weak hydraulic movement).

Solution:

• Replace cylinder seals, check cylinder holding pressure.

• Correct or replace deformed linkages, rocker arms.

• Follow hydraulic system troubleshooting methods to increase system pressure.

6. Common Travel Device Faults

6.1 Veering or Inability to Move
Fault Causes:

• Uneven track tension or uneven track wear.

• Faulty travel motor or reducer (e.g., hydraulic motor internal leakage, gear damage).

• Sticking travel control valve spool, causing uneven flow.

Solution:

• Adjust track tension cylinder, replace severely worn track pads.

• Disassemble travel motor, replace damaged plunger or distribution plate; repair reducer gears.

• Clean travel control valve, repair or replace valve spool.

6.2 Abnormal Noise or Vibration During Travel
Fault Causes:

• Damaged drive wheel, idler wheel, or track roller bearings.

• Worn track chain links, poor meshing.

• Faulty travel motor balance valve, causing shock.

Solution:

• Replace damaged wheels and bearings, lubricate them.

• Replace worn track links or complete tracks.

• Repair balance valve, replace valve spool or springs.

Fault Diagnosis Precautions

1. Safety First: Always turn off the engine, engage the parking brake, block the tracks, and disconnect the negative terminal of the battery before repairs.

2. Step-by-Step Diagnostics: Follow the principle of "start easy, then difficult, from outside to inside," such as checking oil and electrical connections first, then disassembling components.

3. Correct Parts Matching: When replacing components, always use OEM or specification-compliant parts to avoid compatibility issues causing new faults.

4. Regular Maintenance: Replace oil, filters as per the manual, and lubricate hinge points regularly to reduce the risk of faults.

By systematically troubleshooting and performing targeted repairs, common excavator faults can be effectively resolved, extending the equipment’s lifespan. For complex faults (such as engine overhaul or hydraulic pump assembly replacement), it is recommended to have professionals or after-sales teams handle the work.