Hitachi EX120-2 System Base Pressure Too Low: Troubleshooting and Solutions

[MikePhua]

Introduction
The Hitachi EX120-2 excavator is a robust machine known for its efficient performance in various construction and digging tasks. However, like all heavy equipment, it can experience mechanical issues over time. One common issue that may arise is when the system base pressure becomes too low. This can lead to poor hydraulic performance, reduced power, and inefficiencies in operation. This article will explore the potential causes and solutions for the "system base pressure too low" issue in the Hitachi EX120-2.
1. Understanding the Issue
"System base pressure" refers to the hydraulic pressure in the system at rest or idle. When this pressure is too low, the hydraulic components, such as the pumps, valves, and cylinders, will not function at optimal levels. This results in reduced lifting capacity, slow or unresponsive movements, and generally poor performance. Understanding the causes of low base pressure is essential in addressing the issue effectively.
2. Common Causes of Low System Base Pressure
Several factors could cause the system base pressure to be too low in the Hitachi EX120-2. Here are the most common causes:

• Low Hydraulic Fluid Levels
  Low hydraulic fluid levels are one of the most frequent causes of low base pressure. Without enough fluid in the system, the pump cannot generate adequate pressure. This can lead to sluggish operation and can even damage the hydraulic components over time.
  
• Hydraulic Pump Malfunction
  A faulty hydraulic pump is another common cause. The pump is responsible for circulating hydraulic fluid through the system, and if it's not functioning properly, the system base pressure will drop. Common issues with the pump include wear, damaged seals, or internal failures.
  
• Clogged Hydraulic Filters
  Hydraulic filters prevent debris and contaminants from entering the hydraulic system. When these filters become clogged, they can restrict fluid flow, which in turn reduces the pressure within the system. This can lead to low base pressure and other hydraulic performance issues.
  
• Faulty Pressure Relief Valve
  The pressure relief valve helps regulate the system's hydraulic pressure by diverting fluid when the pressure reaches unsafe levels. If this valve malfunctions or is stuck open, it can cause the system pressure to remain too low, as fluid is continuously diverted.
  
• Leaking Hydraulic Lines or Fittings
  Any leaks in the hydraulic lines, hoses, or fittings can result in a loss of hydraulic fluid, leading to a drop in system base pressure. Leaks can also cause fluid contamination, which further exacerbates the issue.
  
• Contaminated Hydraulic Fluid
  Contaminants such as dirt, water, or air in the hydraulic fluid can cause inefficiencies in the hydraulic system. Contaminated fluid can lead to the breakdown of seals, clog filters, and affect the operation of the pump, all contributing to low system pressure.
  

3. Troubleshooting Low System Base Pressure
To fix the "system base pressure too low" issue, follow these troubleshooting steps:

• Step 1: Check Hydraulic Fluid Levels
  Begin by checking the hydraulic fluid levels. If they are low, refill the system with the appropriate hydraulic fluid. Ensure that the fluid is clean and free from contaminants.
  
• Step 2: Inspect the Hydraulic Pump
  If the fluid levels are sufficient, inspect the hydraulic pump. Look for signs of wear or damage, such as leaks or abnormal noises. A malfunctioning pump may need to be repaired or replaced.
  
• Step 3: Clean or Replace Hydraulic Filters
  Check the hydraulic filters for dirt and debris. If the filters are clogged, clean or replace them as needed. Clean filters will allow for optimal fluid flow and help maintain proper system pressure.
  
• Step 4: Check for Leaks
  Inspect all hydraulic lines, hoses, and fittings for any visible signs of leakage. If you find a leak, repair or replace the damaged component to prevent further loss of fluid and pressure.
  
• Step 5: Test the Pressure Relief Valve
  The pressure relief valve should be checked to ensure it is functioning properly. If the valve is stuck open or malfunctioning, it will need to be cleaned or replaced to restore proper pressure regulation.
  
• Step 6: Flush the Hydraulic System
  If contamination is suspected, flush the hydraulic system to remove any dirt, water, or air trapped in the fluid. This will prevent further damage to the system and improve hydraulic performance.
  

4. Solutions for Low System Base Pressure
Once you've identified the cause of the low system base pressure, here are some potential solutions:

• Refill Hydraulic Fluid
  If the fluid levels are low, simply topping off the system with the correct fluid type may restore the pressure and improve performance.
  
• Repair or Replace the Hydraulic Pump
  If the pump is found to be faulty, it may need to be repaired or replaced. A new, efficient pump will ensure the system receives adequate pressure.
  
• Replace Clogged Filters
  Replace any clogged hydraulic filters with new ones to restore fluid flow and prevent future issues.
  
• Seal or Replace Leaking Components
  Fix any leaks in the hydraulic system by replacing worn-out seals, hoses, or fittings. This will prevent fluid loss and maintain the correct pressure.
  
• Fix or Replace the Pressure Relief Valve
  A faulty pressure relief valve can be replaced or repaired to ensure that the hydraulic pressure is regulated correctly.
  
• Flush and Replace Contaminated Fluid
  If the fluid is contaminated, a thorough flush of the system and replacement of the hydraulic fluid can improve system pressure and overall performance.
  

5. Conclusion
A low system base pressure in the Hitachi EX120-2 excavator can lead to poor hydraulic performance and reduced machine efficiency. The issue can stem from several causes, including low hydraulic fluid levels, a malfunctioning pump, clogged filters, or leaks in the hydraulic system. By following a systematic troubleshooting approach and applying the necessary solutions, you can restore the hydraulic pressure and ensure that your Hitachi EX120-2 operates at its full potential. Regular maintenance, such as checking fluid levels and replacing filters, can help prevent this issue from arising in the future.