main cause:
1. Insufficient air volume
2. Insufficient or substandard coolant
3. Abnormal oil level
4. Use inferior fuel
5. Thermostat fault
Diagnosis process of poor operation of water pump:
Step 1: check and confirm whether the engine of Hitachi excavator is high temperature due to long-term overload operation or high ambient temperature.
Step 2: check whether the coolant level is normal. If it is less, fill it.
Step 3: check whether the fan belt slips. If it is loose, adjust it. If there is oil stain, clean it and replace it if necessary; Check whether the fan blade is deformed or damaged. If it is deformed or damaged, replace it; Check whether the air guide cover is damaged or improperly positioned. If it is improper, adjust it or replace it if it is damaged; Check the sealing around the radiator. If the sealing is poor, strengthen the sealing; Check whether the radiator rib is blocked by sundries, resulting in poor ventilation. If yes, clean it.
Step 4: check whether the oil level is at the specified position. If it is not, fill or release the oil 4 to the specified position.
Step 5: know whether the user has been using qualified antifreeze or soft water. If so, clean the water tank and water channel, and replace the damaged parts in serious cases.
Step 6: check whether the fuel quality meets the standard. If not, clean the oil tank, oil passage and oil-water separator, and replace the fuel filter and fuel.
Step 7: check whether the thermostat works normally and replace it if not.
Step 8: check whether the water pump works normally. If not, replace it.
