Key points for advanced inspection of excavators: Avoiding hidden traps and quantitative detection methods

June 12, 2026

Precise inspection of the swivel support (rotating platform)
Clearance between upper and lower parts: Measured using a dial indicator. By moving the crawler frame and the turntable joint, if the gap exceeds 3mm, it indicates severe wear.
Torque of bolts: 8 connecting bolts were randomly inspected. Any signs of loosening or fracture indicate poor maintenance.
2. Quantitative test for internal leakage of hydraulic cylinders
Raise the boom to its maximum height, shut off the engine, and the descent distance within 10 minutes:
Quality: ≤ 5mm;
Warning: 10 - 20 mm;
Wear-out: > 30mm.
Test the boom and bucket cylinders in the same way.
3. Actual measurement of main pump pressure and flow rate
Connect the pressure gauge and perform the "braking" operation. The actual measured pressure of the main pump should be no less than 85% of the original factory value.
At the same time, observe the speed of pressure build-up. If it is slow, it indicates that there is leakage inside the pump.
4. Actual state of the cooling system
After working continuously for 30 minutes, measure with an infrared thermometer:
The temperature difference between the inlet and outlet of the hydraulic oil radiator should be ≥ 8℃.
The water temperature should be maintained at 75 to 90 degrees Celsius. If it exceeds 95 degrees Celsius, there will be poor heat dissipation or a malfunction of the thermostat.
5. Electrical Fault Code Check
Enter the monitoring panel to retrieve the historical fault codes. Focus on recording:
"Abnormality in the fuel injection system"
"Common rail pressure is low"
"CAN bus communication has been interrupted."
After cleaning, perform the test again and read the fault code. The fault code that reappears is the most reliable.
6. Judgment of aging of rubber parts and hoses
Press the hydraulic hose and immediately mark any hardened areas or visible cracks.
Check the shock absorber blocks in the cab and the engine foot pads. If they are not elastic or have any cracks, it indicates that the machine vibrates severely and is not properly maintained.
7. Hidden Information on Uneven Wear of Tracks
Measure the difference in pitch between the left and right track sections. If it exceeds 5%, it indicates long-term unilateral steering (possibly due to being trapped or operating in violation of regulations).
Check if the wear surface of the guide wheel is eccentric. An eccentric wear indicates that the vehicle has been running off course for a long time.
8. High-tech Identification of Second-hand Watch Repairing
Read the internal working hours of the ECM/Pump controller and compare them with the hours shown on the instrument.
Check the proportion of idle time (for modern excavators, a storage idle time ratio of over 30% is normal; a too low ratio may have been tampered with).
9. Rapid judgment through oil sample collection
The engine oil dripped onto the filter paper. After 24 hours, observe:
Large black core and narrow diffusion layer → Severe carbon deposition;
Metal powder reflection → Abnormal wear.
Hydraulic oil drops on the white paper, with a large black circle in the middle → Severe oxidation or old oil has been mixed in.
10. Work device clearance quantification table
Part Normal Gap Needs Repair Dangerous
Shaft of the boom <0.5mm 1-2mm >3mm
Hinge joint between the bucket arm and the bucket <1mm 2-3mm >4mm