Troubleshooting Jerky Hydraulic Operations on the Bobcat E85

[MikePhua]

Introduction
The Bobcat E85 is a highly regarded mini-excavator used for digging and heavy lifting tasks in tight spaces. One of the critical components for smooth operation is the hydraulic system, which controls movement, lifting, and attachment functions. However, some users have reported jerky hydraulic operations, affecting the performance and efficiency of the machine. This article explores common causes behind jerky hydraulic functions on the Bobcat E85 and offers troubleshooting tips to resolve these issues.
Understanding the Hydraulic System on the Bobcat E85
The hydraulic system on the Bobcat E85 consists of pumps, hoses, cylinders, and valves that work together to power the movement of the boom, arm, bucket, and other attachments. When the hydraulic system functions properly, it provides smooth, precise control over the machine's operations. Jerky or uneven hydraulic movements can cause delays and inefficiencies, particularly in tasks that require fine control.
Common Symptoms of Jerky Hydraulic Operations
Forum users reported various symptoms of jerky hydraulic operations on the Bobcat E85, including:

1. Erratic Movements
   • Description: Jerky, uneven, or sudden jerks during the operation of the boom, bucket, or arm. This issue may occur when the machine is attempting to lift, move, or perform fine control functions.
     
   • Causes: This could be caused by hydraulic fluid inconsistencies, air in the system, or problems with the control valves.
     
2. Slow or Delayed Response
   • Description: A slow or delayed response when the joystick or controls are moved. The hydraulic system may hesitate before moving the arm, bucket, or attachment.
     
   • Causes: Low hydraulic fluid levels, worn-out seals, or issues with the hydraulic pumps can lead to delayed response times.
     
3. Uneven Power Distribution
   • Description: Uneven lifting or movement on different sides of the machine. One side of the boom or attachment may operate more smoothly than the other.
     
   • Causes: This can be a result of problems with the hydraulic lines or unequal fluid pressure due to a malfunctioning pump or valve.
     

Possible Causes of Jerky Hydraulic Operations
Several factors can contribute to jerky hydraulic operations on the Bobcat E85. Below are the most common causes discussed by forum users:

1. Low Hydraulic Fluid Levels
   • Description: Low hydraulic fluid levels can lead to air being drawn into the system, which can cause erratic or jerky movements.
     
   • Solution: Check the hydraulic fluid levels and top up as needed using the appropriate fluid type. Be sure to inspect for leaks that could be causing the low levels.
     
2. Air in the Hydraulic System
   • Description: Air trapped in the hydraulic lines can cause irregular pressure in the system, leading to jerky or uneven movements.
     
   • Solution: Bleed the hydraulic system to remove air pockets. This process can vary depending on the machine and may require running the system through its full range of motion while checking for any signs of air bubbles.
     
3. Contaminated or Old Hydraulic Fluid
   • Description: Contaminated or degraded hydraulic fluid can lose its lubricating and pressure-regulating properties, causing jerky movements or inconsistent operation.
     
   • Solution: Drain and replace the hydraulic fluid. Ensure you use high-quality fluid recommended for the Bobcat E85. Regular fluid changes can prevent contamination from affecting the system.
     
4. Faulty Hydraulic Pump
   • Description: A malfunctioning or worn-out hydraulic pump can cause inadequate fluid pressure, leading to jerky or delayed movements.
     
   • Solution: Inspect the pump for signs of wear or damage. If the pump is malfunctioning, it may need to be repaired or replaced.
     
5. Worn or Damaged Hydraulic Valves
   • Description: The valves that regulate the flow of hydraulic fluid can become worn or clogged over time, leading to uneven pressure and jerky operation.
     
   • Solution: Inspect the hydraulic valves and check for any signs of wear, blockage, or malfunction. Cleaning or replacing the valves may be necessary.
     
6. Faulty Control Joystick or Valve
   • Description: A faulty joystick or control valve can cause erratic hydraulic movements, especially if there’s an issue with the signal sent to the hydraulic control system.
     
   • Solution: Test the joystick and associated control valves. If the joystick is not responding smoothly, it may need to be repaired or replaced.
     

Steps for Troubleshooting and Resolving Jerky Hydraulic Issues
Here are the troubleshooting steps recommended by forum members to resolve jerky hydraulic issues on the Bobcat E85:

1. Check Fluid Levels and Quality
   • Action: Start by checking the hydraulic fluid levels and ensuring the fluid is clean and at the correct level. If the fluid is low, top it up with the recommended hydraulic fluid. If the fluid appears dirty, it may need to be replaced.
     
2. Inspect for Leaks
   • Action: Look for visible leaks in the hydraulic system, including hoses, fittings, and cylinders. Leaks can result in a drop in fluid pressure and cause jerky movements. Repair any leaks you find before continuing with further troubleshooting.
     
3. Bleed the Hydraulic System
   • Action: If air is suspected in the hydraulic lines, bleed the system to remove any trapped air. Operate the machine through its full range of motion while monitoring the system for smoothness.
     
4. Examine the Hydraulic Pump and Valves
   • Action: Inspect the hydraulic pump for signs of wear or failure. Also, check the valves to ensure they are not clogged or damaged. Repair or replace the pump and valves if necessary.
     
5. Test the Control System
   • Action: Test the joystick and control valves for proper functionality. If there is any resistance or irregular movement, it may indicate a malfunctioning control system that requires attention.
     
6. Perform a Full System Check
   • Action: If the problem persists, consider running a full diagnostic check on the entire hydraulic system, including sensors, filters, and the control system. A professional technician may be required for in-depth testing.
     

Preventive Maintenance Tips for Smooth Hydraulic Operation
To prevent future hydraulic issues, it’s important to follow regular maintenance practices for the Bobcat E85:

1. Regularly Check Hydraulic Fluid
   • Action: Frequently check the hydraulic fluid levels and quality, especially after extended use. This helps to avoid low fluid levels or contamination, which can cause operational issues.
     
2. Clean the Hydraulic System
   • Action: Keep the hydraulic lines, filters, and components clean and free from debris. Regular cleaning can prevent blockages and damage to the system.
     
3. Replace Hydraulic Filters Regularly
   • Action: Change the hydraulic filters at regular intervals to ensure the fluid remains free from contaminants. Dirty filters can lead to fluid degradation and system damage.
     
4. Monitor for Leaks
   • Action: Routinely inspect the hydraulic system for leaks and promptly address any issues to prevent fluid loss and pressure inconsistencies.
     

Conclusion
Jerky hydraulic operations on the Bobcat E85 can significantly impact the machine’s performance and productivity. By identifying the root cause—whether it’s low fluid, air in the system, contaminated fluid, or mechanical issues like worn pumps or valves—operators can take the necessary steps to restore smooth hydraulic function. Regular maintenance, timely fluid changes, and system inspections are essential to prevent hydraulic problems and keep the Bobcat E85 operating at peak performance.