Pump Bogging Issues in Hitachi EX200 Excavators: Diagnosis and Solutions

[MikePhua]

The Hitachi EX200 is a popular model in the EX series of excavators, well-regarded for its performance, durability, and versatility in various construction and mining applications. However, one of the common issues encountered by operators is pump bogging, a situation where the hydraulic pump struggles to maintain the required flow or pressure. This problem can lead to reduced performance, increased wear, and potential system failure if left unaddressed. Understanding the causes of pump bogging and how to resolve it is crucial for maintaining the efficiency and longevity of the machine.
What is Pump Bogging?
Pump bogging refers to a situation where the hydraulic pump fails to deliver the appropriate pressure or flow, causing the machine’s hydraulic system to lag or struggle during operation. This could manifest in various ways, such as sluggish or delayed arm movements, reduced lifting capacity, or difficulty in maintaining hydraulic pressure under load. When the pump bogs down, the engine may also show signs of strain or reduced power output.
The hydraulic system in the Hitachi EX200 is designed to be highly responsive, so any delay or failure in hydraulic action can significantly impact the machine’s performance. This issue is often linked to either the pump’s internal components or other related systems such as the engine, filters, or fluid levels.
Common Causes of Pump Bogging in Hitachi EX200
Several factors could contribute to pump bogging in the Hitachi EX200. Understanding these causes is the first step in troubleshooting and preventing further damage to the machine’s hydraulic system.

1. Low Hydraulic Fluid Level
   One of the simplest yet most common causes of pump bogging is a low hydraulic fluid level. Hydraulic fluid plays a critical role in providing the necessary pressure for the pump to function properly. If the fluid level is too low, it may cause the pump to suck in air, leading to cavitation, erratic pump performance, or complete failure to generate pressure.
   Solution: Regularly check the fluid level and top it off as needed. Always use the recommended hydraulic fluid to ensure optimal performance.
   
2. Contaminated Hydraulic Fluid
   Over time, the hydraulic fluid in the system can become contaminated with dirt, metal particles, or moisture. This contamination can cause the pump components to wear prematurely, leading to inefficiency and bogging. Dirty fluid can also clog filters and restrict the flow of hydraulic fluid.
   Solution: Change the hydraulic fluid regularly as per the manufacturer’s recommendations. Additionally, inspect and clean the filters to ensure that no debris is circulating through the system.
   
3. Clogged or Dirty Hydraulic Filters
   The hydraulic system in the EX200 is equipped with filters to catch impurities before they can damage the pump or other components. If the filters become clogged, the pump may not receive adequate fluid, leading to pump bogging and potential overheating.
   Solution: Inspect the hydraulic filters for any signs of clogging or dirt buildup. Replace or clean the filters to ensure proper fluid flow. Regular maintenance is essential for avoiding this issue.
   
4. Faulty or Worn Hydraulic Pump
   A worn or damaged hydraulic pump can be a direct cause of pump bogging. Over time, seals, pistons, and other internal components within the pump can wear out, leading to decreased efficiency and a failure to build up the necessary pressure. In some cases, this can lead to a complete pump failure.
   Solution: If the pump is found to be faulty, it may need to be repaired or replaced. Regular inspection of the pump’s internal components can help identify signs of wear before they become a major issue.
   
5. Air in the Hydraulic System
   Air trapped in the hydraulic lines can cause cavitation, which leads to erratic pump performance and a decrease in pressure. This air can enter the system through loose connections, damaged seals, or improper fluid filling.
   Solution: Bleed the hydraulic system to remove any trapped air. Ensure that all seals and connections are tight and in good condition to prevent air from entering the system.
   
6. Malfunctioning Pressure Relief Valve
   The pressure relief valve controls the maximum pressure that the hydraulic pump can generate. If the valve is malfunctioning or set incorrectly, it can cause the pump to underperform, resulting in bogging. A stuck relief valve can either restrict the flow of fluid or allow too much fluid to bypass the pump.
   Solution: Inspect the pressure relief valve for correct operation. If it is faulty or clogged, replace or clean it. Ensure that the valve is adjusted to the correct pressure settings specified by the manufacturer.
   
7. Excessive Load on the Pump
   If the excavator is used to lift or move loads beyond its rated capacity, the pump may be under excessive strain, leading to bogging. This can happen when the machine is used for operations it was not designed for or when the operator applies too much pressure to the system.
   Solution: Always ensure that the machine is used within its rated limits. Avoid overloading the machine and maintain proper operating procedures.
   

How to Prevent Pump Bogging in the Hitachi EX200
Prevention is always better than cure, and regular maintenance can significantly reduce the risk of pump bogging in the Hitachi EX200. Some essential tips for preventing this issue include:

1. Follow Regular Maintenance Intervals
   Always adhere to the manufacturer’s recommended maintenance schedule. This includes checking hydraulic fluid levels, replacing filters, and inspecting the pump and other components regularly.
   
2. Use High-Quality Hydraulic Fluids
   Invest in high-quality hydraulic fluid that meets the specifications outlined in the EX200’s operator manual. Using the right fluid ensures that the hydraulic system operates efficiently and prevents issues such as pump bogging.
   
3. Inspect and Clean Hydraulic Components
   Make it a habit to inspect hydraulic hoses, pumps, valves, and filters for any signs of wear or damage. Keeping these components clean and in good working order will minimize the chances of hydraulic issues.
   
4. Train Operators Properly
   Ensure that machine operators are well-trained in the proper use of the excavator, including not overloading the system and recognizing when the machine is under strain. Proper operational practices can prevent excessive wear on the hydraulic system and help maintain overall machine health.
   

Conclusion
Pump bogging in the Hitachi EX200 is a common issue that can significantly affect machine performance if not addressed promptly. The problem can stem from a variety of causes, including low hydraulic fluid, contaminated fluid, clogged filters, or a faulty pump. By following regular maintenance procedures, using high-quality hydraulic fluid, and inspecting the system regularly, operators can minimize the risk of pump bogging and keep their excavators running efficiently. Early detection and corrective actions are key to preventing costly repairs and ensuring the longevity of the machine.