Hitachi EX120-2 Excavator – Troubleshooting and Maintenance Tips

[MikePhua]

Introduction
The Hitachi EX120-2 is a compact, versatile excavator designed for a variety of construction and excavation tasks. Like any piece of heavy machinery, the EX120-2 requires regular maintenance and attention to ensure its longevity and optimal performance. This article will guide you through common issues, troubleshooting techniques, and essential maintenance tips for the EX120-2 model.
Common Issues with the Hitachi EX120-2

1. Hydraulic System Failures
   • Symptom: The excavator’s hydraulic functions, such as arm movement or boom operation, become sluggish or unresponsive.
     
   • Cause: Hydraulic issues often arise from fluid contamination, low fluid levels, or damaged hydraulic hoses.
     
   • Solution: Check the hydraulic fluid levels and quality, replacing any contaminated fluid. Inspect hydraulic hoses for leaks or wear and replace as necessary. Regularly change hydraulic filters to prevent clogging.
     
2. Engine Overheating
   • Symptom: The engine temperature gauge runs higher than normal, or the machine shuts down due to overheating.
     
   • Cause: Overheating can be caused by a malfunctioning radiator, clogged cooling system, or insufficient coolant.
     
   • Solution: Inspect the radiator for leaks, blockages, or debris. Clean or replace the radiator as needed. Ensure the coolant levels are correct and flush the system if necessary to remove debris.
     
3. Electrical Problems
   • Symptom: Electrical components, such as lights, gauges, or starting mechanisms, malfunction or fail completely.
     
   • Cause: Electrical failures can stem from loose connections, blown fuses, faulty wiring, or issues with the alternator or battery.
     
   • Solution: Inspect the electrical connections for corrosion or looseness. Check the battery charge and test the alternator to ensure the charging system is working. Replace any damaged or faulty components.
     
4. Starting Issues
   • Symptom: The excavator struggles to start or does not start at all.
     
   • Cause: Common causes of starting issues include a dead battery, faulty starter motor, or fuel delivery problems.
     
   • Solution: First, check the battery charge and connections. If the battery is fine, test the starter motor and fuel system. Inspect the fuel filters and injectors to ensure proper fuel flow.
     
5. Excessive Smoke from Exhaust
   • Symptom: The engine produces an excessive amount of smoke, particularly when under load.
     
   • Cause: Excessive exhaust smoke can indicate poor combustion, typically due to clogged air filters, bad fuel injectors, or worn-out piston rings.
     
   • Solution: Check and replace the air filters if they are dirty or clogged. Inspect the fuel injectors for proper operation and clean or replace them if necessary. If the issue persists, check the piston rings and consider performing an engine overhaul if necessary.
     

Maintenance Tips for the Hitachi EX120-2

1. Regular Fluid Checks
   • Regularly check and replace fluids, including engine oil, hydraulic fluid, and coolant. Dirty or contaminated fluids can cause a wide range of issues, including poor performance and system failures.
     
2. Filter Replacements
   • Change the engine, hydraulic, and air filters at the recommended intervals to maintain optimal performance. Clogged filters can lead to overheating, reduced power, and increased wear on the engine and hydraulic components.
     
3. Track and Undercarriage Maintenance
   • Inspect the tracks and undercarriage regularly for wear, damage, or loose components. Lubricate the track rollers and ensure the track tension is within the manufacturer’s recommended limits to prevent uneven wear or track failure.
     
4. Engine Cooling System
   • Clean the radiator and cooling system periodically to remove dirt, debris, or obstructions. A clogged or dirty radiator can reduce the efficiency of the cooling system, leading to overheating issues.
     
5. Grease All Moving Parts
   • Regularly grease all pivot points, joints, and moving parts to reduce friction and wear. This is especially important for the arm, boom, and bucket connections, which experience high stress during operation.
     
6. Battery Maintenance
   • Check the battery for proper charge levels and clean the terminals to prevent corrosion. If the battery is old or damaged, replace it to avoid starting issues.
     
7. Check and Replace Belts
   • Inspect the engine belts for wear and replace them as necessary. Worn or damaged belts can lead to engine performance issues or even engine failure.
     

Troubleshooting and Repair

1. Check for Fault Codes
   • If the EX120-2 is equipped with a diagnostic system, use it to check for any fault codes. These codes can provide insight into specific issues within the hydraulic, electrical, or engine systems, making troubleshooting faster and more accurate.
     
2. Visual Inspections
   • Perform routine visual inspections of the machine, focusing on areas that are prone to wear or damage, such as hydraulic hoses, electrical connections, and moving parts. A quick inspection can help catch problems early, preventing more expensive repairs down the line.
     
3. Test Hydraulic Pressure
   • If you suspect hydraulic issues, use a pressure gauge to test the hydraulic system. Low pressure can indicate problems with the pump, filters, or relief valve. Follow the manufacturer’s guidelines for proper pressure settings.
     

Conclusion
The Hitachi EX120-2 excavator is a reliable and efficient machine when properly maintained. Regular checks of the engine, hydraulic system, electrical components, and undercarriage are essential to keeping the machine in good working order. By addressing common issues such as hydraulic system failures, overheating, and electrical problems early on, operators can ensure the longevity of their equipment and reduce the risk of costly repairs. Regular maintenance, including fluid changes, filter replacements, and visual inspections, will help maintain the machine’s performance and extend its service life.