Troubleshooting Engine Problems on the Hitachi EX-120: Solutions and Insights

[MikePhua]

The Hitachi EX-120 is a popular mid-size hydraulic excavator known for its reliability in various construction, mining, and digging applications. However, like all machines, it can face technical issues, particularly with its engine. One common problem that many operators encounter is engine malfunctions, such as starting issues, stalling, or poor performance. Understanding how to troubleshoot these problems can save both time and money, ensuring the machine runs smoothly and efficiently.
Common Engine Problems on the Hitachi EX-120
Engine issues on the Hitachi EX-120 can arise due to a variety of factors, from fuel-related problems to electrical failures. Here are some of the most common engine problems faced by operators:

1. Starting Issues
   One of the most frequent problems experienced by operators is the failure of the engine to start or starting intermittently. A machine that doesn't start properly can bring an entire project to a halt, costing valuable time.
   • Possible Causes: Low battery voltage, faulty starter motor, or fuel delivery issues.
     
   • Solution: Check the battery for charge and ensure all electrical connections are secure. If the battery is fine, inspect the starter motor for wear or faults. Fuel delivery issues may also cause starting problems, particularly if the fuel filter is clogged or the fuel system has air in it.
     
2. Engine Stalling
   The EX-120 engine might run for a while and then stall suddenly, which is both dangerous and frustrating. This can happen during operation or when idling, interrupting work and reducing productivity.
   • Possible Causes: Fuel starvation, air in the fuel lines, or clogged filters.
     
   • Solution: Start by checking the fuel system. Ensure that fuel is reaching the engine without obstruction. Check the fuel lines and filter for any clogs or damage. Air in the fuel lines can also cause stalling, so bleed the fuel system to remove any trapped air.
     
3. Loss of Power
   A noticeable drop in engine power can significantly affect the performance of the excavator. The machine may struggle to lift or dig efficiently, or it might lose power suddenly during use.
   • Possible Causes: Clogged air filters, low fuel pressure, or issues with the turbocharger or intercooler.
     
   • Solution: Inspect the air filter for dirt or debris, as a clogged filter can restrict airflow to the engine, causing power loss. If the air filter is clean, check the fuel pressure and replace any damaged fuel components. Also, examine the turbocharger and intercooler for proper operation, as issues with these components can directly affect engine power.
     
4. Overheating
   Overheating is a common problem, especially in hot climates or under heavy use. If the engine temperature exceeds the normal operating range, it can cause damage to various internal components, leading to more severe issues down the road.
   • Possible Causes: Low coolant levels, faulty thermostat, or blocked radiator.
     
   • Solution: Check the coolant levels and refill if necessary. Inspect the radiator for blockages or dirt buildup that might be preventing proper airflow. A faulty thermostat can also cause overheating, so consider replacing it if it’s malfunctioning.
     

Step-by-Step Troubleshooting Process
When dealing with an engine problem, a systematic troubleshooting approach is essential to accurately diagnose and fix the issue. Here’s a step-by-step guide that operators can follow:

1. Check the Battery and Electrical System
   The first thing to inspect when facing engine problems is the battery. If the battery is weak or dead, it will prevent the engine from starting. Make sure the battery is charged and that all connections are clean and secure. Also, check for any signs of corrosion on the terminals.
   • Example: A construction company in Alaska experienced starting problems with their Hitachi EX-120 during the winter months. After testing the battery, they found that it had lost charge due to the cold. Replacing the battery and using a heater to keep the machine’s electrical systems warm in cold conditions solved the issue.
     
2. Inspect the Fuel System
   Fuel-related issues are among the most common causes of engine failure. Begin by inspecting the fuel tank, lines, and filter. A clogged fuel filter can block the flow of fuel to the engine, while air in the fuel system can prevent the engine from starting or cause it to stall.
   • Example: An operator in Texas found that their Hitachi EX-120 would stall repeatedly, especially when lifting heavy loads. After inspecting the fuel system, they discovered a clogged fuel filter, which was replaced, resolving the stalling issue.
     
3. Examine the Air Intake System
   A blocked or dirty air filter can significantly reduce engine performance. If the air filter is clogged, it will restrict airflow to the engine, causing a drop in power and potentially causing the engine to stall.
   • Example: An operator working in a construction site with heavy dust conditions noticed a significant power loss in their Hitachi EX-120. After inspecting the air filter, they found it completely clogged with dust. Cleaning or replacing the air filter restored full engine power and performance.
     
4. Check the Cooling System
   Overheating can be a major problem, especially during long workdays or in hot climates. Ensure that the radiator is clean and free of debris, and check that the coolant levels are adequate. If the engine is overheating regularly, inspect the thermostat and water pump to ensure they’re functioning properly.
   • Example: A mining company in Australia faced frequent overheating issues with their Hitachi EX-120, especially during long shifts in the summer. After cleaning the radiator and replacing a malfunctioning thermostat, the overheating problem was resolved, and the equipment continued to run smoothly.
     
5. Test the Turbocharger and Intercooler
   If the engine is losing power, it may be due to a malfunctioning turbocharger or intercooler. The turbocharger is responsible for increasing air intake to the engine, and if it’s damaged or not working properly, the engine will struggle to generate sufficient power.
   • Solution: Check the turbocharger for any signs of damage or excessive wear, and ensure that the intercooler is clean and free of blockages. If necessary, replace the turbocharger or intercooler components.
     

Common Maintenance Practices to Prevent Engine Problems
Regular maintenance is the key to preventing engine issues on the Hitachi EX-120. Here are some essential maintenance practices to keep the engine running smoothly:

1. Regular Fluid Checks
   Ensure that engine oil, coolant, and hydraulic fluids are checked regularly and replaced according to the manufacturer’s schedule. Using the correct type and amount of fluid is crucial to maintaining engine health.
   
2. Fuel and Air Filter Replacement
   Regularly replace fuel and air filters to ensure that the engine receives clean fuel and air. A clogged filter can lead to poor performance, engine stalling, or starting issues.
   
3. Engine Block Heater
   In colder climates, an engine block heater can prevent the engine oil from thickening and causing starting problems. Make sure to use a block heater when necessary, especially in winter months.
   
4. Scheduled Engine Inspections
   Regularly inspect the engine components, including belts, hoses, and wiring, for wear and tear. Addressing minor issues before they become major problems can prevent unexpected downtime.
   

Conclusion: Keeping the Hitachi EX-120 Running Smoothly
The Hitachi EX-120 is a reliable machine, but like all equipment, it can face engine-related issues that need attention. Whether it’s starting problems, stalling, power loss, or overheating, following a systematic troubleshooting process can help operators quickly identify and resolve the issue. Regular maintenance is also essential to prevent these problems from arising in the first place. By staying vigilant and proactive with maintenance and repairs, operators can ensure that their Hitachi EX-120 continues to perform at its best, minimizing downtime and improving productivity on the job site.