Hydraulic Pump Stalling Issues on Hitachi EX200

[MikePhua]

The Hitachi EX200 is a well-regarded model in the world of construction machinery, known for its durability and performance in heavy-duty environments. However, like any machine, it can experience issues that affect its operational efficiency. One common problem that some operators face with the Hitachi EX200 is the engine stalling due to hydraulic pump malfunctions. This issue, while not unusual in older or heavily used machines, requires immediate attention to avoid further damage to the hydraulic system or the engine.
Understanding the hydraulic system of the EX200 is crucial for diagnosing and fixing problems like this. The EX200, like other hydraulic excavators, relies heavily on its hydraulic pump to move fluid to various parts of the machine, allowing it to perform functions like lifting, digging, and steering. If the hydraulic pump is failing or malfunctioning, it can lead to engine stalling, overheating, or even complete system failure.
Symptoms of Hydraulic Pump Problems
When the hydraulic pump fails or malfunctions in the Hitachi EX200, there are typically a few symptoms that operators should look out for:

1. Engine Stalling: The most obvious sign of a hydraulic pump problem is the engine stalling or bogging down during operation. This happens because the hydraulic system demands more power than the engine can provide, overwhelming the engine and causing it to stall.
   
2. Reduced Hydraulic Power: The machine may experience a significant loss in hydraulic power. If the hydraulic pump is not functioning properly, it will be unable to deliver the necessary pressure to the system, resulting in weak or delayed actions when operating the arm or bucket.
   
3. Unusual Sounds: A failing hydraulic pump may produce strange noises, such as whining, grinding, or even a pulsating sound. These noises can indicate air in the hydraulic lines or internal damage to the pump components.
   
4. Overheating: Hydraulic systems are designed to operate under high pressure, and when the pump is struggling, it can generate excessive heat. Overheating of the hydraulic fluid can further damage the system and lead to more serious mechanical issues.
   

Causes of Hydraulic Pump Stalling
Several factors can contribute to the hydraulic pump stalling the engine. Understanding these causes is essential for troubleshooting and making the necessary repairs:

1. Low Hydraulic Fluid Levels: One of the most common causes of hydraulic pump problems is insufficient fluid levels. Hydraulic systems rely on adequate fluid levels to operate properly. If the fluid is too low, the pump may struggle to generate the pressure needed, causing the engine to stall.
   
2. Contaminated Hydraulic Fluid: Contaminants such as dirt, debris, or water in the hydraulic fluid can damage the internal components of the hydraulic pump. These contaminants can cause the pump to become clogged or to wear out prematurely, which can lead to engine stalling.
   
3. Worn Hydraulic Pump Components: Over time, the internal parts of the hydraulic pump, such as gears, seals, and pistons, can wear out. When these components become damaged, the pump’s efficiency decreases, causing it to struggle under load and potentially stall the engine.
   
4. Faulty Pressure Relief Valve: The pressure relief valve is a critical component of the hydraulic system that ensures the pressure does not exceed safe limits. If this valve malfunctions or becomes stuck, it can cause the hydraulic pump to operate at dangerously high pressures, leading to engine stalling.
   
5. Air in the Hydraulic System: Air trapped in the hydraulic lines can lead to cavitation, a process where air bubbles cause a reduction in pressure and system efficiency. This can damage the pump and cause it to fail, which in turn may stall the engine.
   

Troubleshooting Hydraulic Pump Issues on Hitachi EX200
If you’re experiencing hydraulic pump-related stalling issues on your Hitachi EX200, here’s a step-by-step guide to help diagnose and fix the problem:

1. Check Hydraulic Fluid Levels: Start by inspecting the hydraulic fluid levels. If the fluid is low, top it up with the manufacturer’s recommended hydraulic oil. Be sure to check for any signs of leaks around the hydraulic lines, hoses, or seals, which could be causing the fluid loss.
   
2. Inspect Hydraulic Fluid Quality: If the fluid appears dirty or contaminated, it may need to be replaced. Contaminated fluid can cause significant damage to the hydraulic pump and other components in the system. Drain the old fluid and replace it with fresh, clean hydraulic oil.
   
3. Examine the Hydraulic Pump: Check the hydraulic pump for any visible signs of damage, wear, or leaks. If the pump is making unusual noises or is overheating, it could be a sign that it’s failing and needs to be replaced.
   
4. Inspect the Pressure Relief Valve: Test the pressure relief valve to ensure it’s functioning properly. If the valve is stuck or malfunctioning, it may be causing excessive pressure in the system. Cleaning or replacing the valve may resolve the issue.
   
5. Check for Air in the System: If there’s air in the hydraulic system, it can lead to cavitation. To remove air, check the hydraulic lines for any leaks or loose connections. Bleed the system to ensure all air is removed.
   
6. Test the System Under Load: Once you’ve completed these checks and repairs, test the machine under load to ensure the hydraulic pump is functioning properly and the engine is no longer stalling.
   

Preventative Maintenance for the Hydraulic System
To avoid hydraulic pump problems and ensure the longevity of your Hitachi EX200, regular maintenance is essential. Here are a few tips for keeping the hydraulic system in good working order:

1. Regular Fluid Checks: Routinely check hydraulic fluid levels and quality. Replace the fluid every 1,000 to 1,500 hours of operation or as recommended by the manufacturer.
   
2. Clean Filters: Ensure that hydraulic filters are cleaned and replaced regularly. Dirty filters can allow contaminants to enter the system, damaging the pump.
   
3. Monitor Pressure Levels: Regularly check the pressure relief valve and monitor system pressures to ensure they are within safe operating limits.
   
4. Inspect Hoses and Seals: Regularly inspect hoses, seals, and fittings for signs of wear, leaks, or damage. Replace any components that are compromised to prevent hydraulic fluid loss.
   

Conclusion
Hydraulic pump issues on the Hitachi EX200, particularly those that cause the engine to stall, can be a frustrating and costly problem. However, by understanding the symptoms, causes, and troubleshooting steps outlined above, operators can effectively diagnose and fix these issues. Regular maintenance and prompt attention to potential problems will help extend the life of the hydraulic system and ensure that the EX200 continues to perform at its best.