Hitachi EX120 Excavator Common Issues and Solutions

[MikePhua]

The Hitachi EX120 is a widely used mid-sized hydraulic excavator, commonly found in construction, mining, and engineering projects. With its efficient performance and durable design, the EX120 is a popular choice for heavy-duty operations. However, like all machinery, it can face certain issues over time. This article addresses common problems encountered with the EX120 and offers potential solutions to help equipment owners and operators extend the lifespan and performance of their machines.
Common Issues

1. Engine Starting Difficulties
   Engine starting problems are a common issue with the EX120. These issues are often caused by a weak battery, starter motor failure, or fuel system problems. Ensuring that the battery is in good condition and regularly checking the fuel system can help avoid these types of problems.
   
2. Hydraulic System Failures
   Hydraulic system failures are one of the frequent issues with the EX120. Low hydraulic oil levels, pump failures, or leaking hydraulic hoses can reduce the system's efficiency or cause complete failure. Regularly checking hydraulic oil levels and the condition of the hoses can help prevent hydraulic system issues.
   
3. Radiator and Cooling System Problems
   Radiator and cooling system issues may lead to engine overheating, which affects machine operation. Common problems include low coolant levels, clogged radiators, or malfunctioning cooling fans. Keeping the cooling system clean and regularly checking coolant levels can help prevent overheating.
   
4. Electrical System Failures
   The electrical system on the EX120, including the starting circuit, sensors, and control modules, can sometimes malfunction. Electrical issues may prevent the machine from starting or cause abnormal behavior in control systems. Loose wiring, blown fuses, or faulty sensors are common causes. Regular inspection of the electrical system and securing wiring connections can reduce electrical failures.
   
5. Travel System Issues
   Travel system problems often manifest as uneven movement, excessive noise, or increased fuel consumption. These issues could be related to travel motors, reduction gears, or drive shafts. Regularly inspecting and maintaining the transmission system can help prevent travel system failures.
   

Troubleshooting and Solutions

1. Engine Starting Difficulties Solutions
   • Check the Battery: Ensure the battery is fully charged and check for corrosion on battery terminals. If the battery is old or damaged, replace it.
     
   • Check the Starter Motor and Electrical System: Inspect the starter motor and related electrical components. If the starter motor is faulty, it should be replaced.
     
   • Check the Fuel System: Inspect the fuel pump, fuel filter, and injectors to ensure there are no blockages or leaks. Clean or replace components as necessary.
     
2. Hydraulic System Failures Solutions
   • Check Hydraulic Oil: Make sure the hydraulic oil is at the correct level and that the oil is clean. Dirty hydraulic oil can reduce system efficiency, so replace the oil if necessary.
     
   • Check the Hydraulic Pump and Hoses: Regularly inspect the hydraulic pump and hoses for any leaks or damage. Replace any damaged hoses or seals promptly.
     
   • Inspect Hydraulic Valves: If hydraulic actions are slow or uneven, check the hydraulic valves for blockages or malfunctions. Repair or replace the valves as required.
     
3. Radiator and Cooling System Problems Solutions
   • Check Coolant Levels: Regularly inspect the coolant level and top it up when necessary. Low coolant levels can cause overheating.
     
   • Clean the Radiator: Remove dirt and debris from the radiator to maintain its efficiency. A clogged radiator can reduce cooling performance.
     
   • Check the Cooling Fan: Inspect the cooling fan to ensure it is functioning properly. Replace any faulty fans to maintain proper cooling.
     
4. Electrical System Failures Solutions
   • Inspect Wiring Connections: Check the electrical system for loose or corroded connections. Clean the terminals and ensure all wires are tightly secured.
     
   • Check Sensors and Control Modules: Inspect sensors for proper functionality. If any sensors are faulty or giving incorrect signals, replace them.
     
   • Replace Fuses: If the electrical system is malfunctioning, check for blown fuses and replace them as necessary.
     
5. Travel System Issues Solutions
   • Check Travel Motors and Reduction Gears: Regularly inspect the travel motors and reduction gears for oil leaks and wear. Maintain proper oil levels and replace damaged components.
     
   • Inspect the Drive Shaft: Check the drive shaft for wear or damage. Replace or repair any faulty shafts to prevent issues with movement.
     

Daily Maintenance Tips

1. Regularly Check Hydraulic Oil and Filters: Hydraulic oil is critical for the proper functioning of the hydraulic system. Regularly check the oil quality and level, and change the oil and filters when needed.
   
2. Clean Air Filters and Intake Systems: Clean the air filters to ensure proper airflow. A clogged air filter can decrease engine efficiency and increase fuel consumption.
   
3. Check the Fuel System: Regularly inspect the fuel filter and injectors to ensure smooth fuel flow.
   
4. Inspect the Transmission and Travel Systems: Check the oil levels in the travel system and transmission regularly. Maintaining the transmission system reduces wear and tear and enhances machine efficiency.
   

Conclusion
The Hitachi EX120 is a reliable and durable machine, well-suited for various construction environments. Regular inspection and maintenance are key to reducing the occurrence of common issues and ensuring the machine runs smoothly over time. By promptly diagnosing and addressing common problems, operators can significantly extend the life of their EX120 and improve operational efficiency. With proper care and attention, the EX120 can continue to perform at its best for many years.