The real condition of a used excavator directly affects its service life, maintenance cost and return on investment. The following provides a set of practical judgment methods from four dimensions: appearance structure, core components, actual test and data verification, combined with industry experience and testing standards, to help you avoid the “problem car” trap.

1. Appearance structure inspection: details reveal the real working conditions

1. Structural parts damage inspection

Boom/arm/chassis:

Weld inspection: Use a strong flashlight to illuminate the weld to observe whether there are cracks, repair marks or deformation (common problems in mining equipment).

Thickness measurement: Use an ultrasonic thickness gauge to detect the thickness of the boom steel plate. If the original thickness is reduced by more than 10%, it may be overloaded for a long time.

Track and chassis:

Chain link gap: Be vigilant if the track link gap exceeds 3mm (normal wear ≤2mm).

Support wheel status: Turn the support wheel. If it is stuck or leaking oil, the chassis may have been overhauled.
2. Covering parts and accessories
Cab: Check whether the glass is original (aftermarket glass has low light transmittance and is prone to visual fatigue).
Bucket teeth: The tooth seat is severely worn but the number of hours is low, which may indicate that the meter is tampered.

II. Core component detection: The engine and hydraulic system are the key
1. Engine performance verification
Cold start test:
When the ambient temperature is ≥5℃, the cold start time should be ≤5 seconds; after starting, the idle speed is stable, without blue smoke (burning oil) or black smoke (incomplete combustion).
Dynamic detection:
When the speed is idling at high speed, the speed fluctuation is ≤±30rpm; when the oil is working at full load, the water temperature is ≤95℃, and the oil pressure is normal.
Leakage check:
There is no oil leakage in the front and rear oil seals of the crankshaft, the turbocharger interface, the oil radiator and other parts.
2. Hydraulic system evaluation
Pressure test:
Use a pressure gauge to detect the main pump pressure (such as the main pump pressure of Carter 320D should be 34.3MPa). Insufficient pressure may cause pump or valve wear.
Action smoothness:
When operating complex actions (such as lifting the boom and rotating at the same time), the hydraulic cylinder does not shake or stagnate, and the return oil pipe temperature is ≤80℃.
Fluid state:
It is normal for the hydraulic oil to be transparent and slightly red. Turbid or emulsified oil needs to be checked for leakage or water ingress.

III. Additional suggestions for avoiding pitfalls
1. Beware of “low price traps”
The price of equipment of the same model and year is more than 20% lower than the market price. It is necessary to focus on checking whether it is an accident vehicle or a mortgaged vehicle.
2. Entrust a third party to test
Professional institutions provide test reports, which can reduce risks by more than 80%.
3. Sign a detailed contract
Key terms:
Vehicle condition standards (such as “no major repair record for the engine”).
Warranty period (recommended ≥3 months).