First, look at the sign
Determine when this excavator is the machine and if it matches the working hours. Some unscrupulous bosses readjusted the number of hours. He originally worked 10,000 hours. He adjusted it to 4,000 hours. It can be seen from the comparison of signs. You can't determine how long the machine has been in actual use, and you have no idea what the value is.
Look at the appearance
It is necessary to carefully observe whether the working device is cracked or additionally fixed by welding, whether there are obvious welding objects on the platform and frame, and whether the cab glass is missing and deformed. It also depends on whether the hood cover is deformed. Sometimes these structural problems do seriously affect work.
It also depends on whether the accessory tube has been used. Some machines have used the accessory tube to install the breaker. If the breaker is installed, the value of this machine will drop by a large amount. Note that it is not a drop, but a large drop. !! Because it was fired, it hurts the entire hydraulic system.
Third, look at the engine
Observe the engine body for any oil leakage. If so, where else? Some are cylinder heads, some are fuel injection pumps, some are cylinder nozzles, some are bottom casings, and some are near the oil filter of the inlet pipe, which can generally be handled, but the cylinder nozzles and fuel injection pumps are difficult to repair and cannot be repaired, and most people are too lazy to handle them. Also check to see if there is dust on the surface of the radiator, and whether the fan's protruding position is normal (usually one-third exposed). If the radiator has too much dust, and the fan is exposed too much or too little, it may cause water temperature. The oil temperature is too high.
Fourth, look at the hydraulic system
Observe the pump body for oil leakage. Rotary motor, distribution valve, travel motor, and pilot system are the keys to the entire hydraulic system. Generally, the machine will work for thousands of hours. If it is poorly maintained, dust will accumulate throughout the interior. Observe whether the accumulated dust is dry or wet. If it is wet, it indicates that there is oil leakage. You must clean it, work for a while, and then wipe it with dry paper to know whether there is oil leakage. Generally, the oil leakage at the joint hose is easier to solve. It is enough to replace the sealing ring, but the internal leakage of the pump body, valve body and motor body is difficult to deal with. It is necessary to disassemble and replace the seals inside. In this case, the value of the machine will of course be much lower.
