Hydraulic Filter Maintenance for Mini Excavators: A Comprehensive Guide

[MikePhua]

Proper maintenance is crucial for keeping any machine running at its best, and mini excavators are no exception. One of the most important maintenance tasks for a mini excavator like the E35 is the timely replacement of the hydraulic filter. This task ensures that the hydraulic system remains clean and functional, preventing costly repairs and downtime due to contamination in the hydraulic fluid.
In this article, we will discuss the importance of hydraulic filter maintenance, how to perform a filter change at the 50-hour mark, and best practices for maintaining the hydraulic system to ensure optimal performance.
Why Hydraulic Filter Maintenance is Important
The hydraulic system in a mini excavator, such as the Bobcat E35, is responsible for powering many of the machine’s key functions, including boom lifting, arm extension, and blade operation. The hydraulic fluid acts as both a lubricant and a power transfer medium. However, over time, the fluid can become contaminated with dirt, debris, and wear particles from inside the hydraulic system.
The hydraulic filter serves as the first line of defense against these contaminants. A clogged or dirty filter can lead to reduced performance, overheating, and even system failure. Regularly changing the filter ensures that the hydraulic fluid stays clean, extending the life of the hydraulic components and maintaining the machine’s performance.
When to Replace the Hydraulic Filter
For most mini excavators, including the Bobcat E35, the manufacturer recommends changing the hydraulic filter at the 50-hour mark for the initial service. After this, you should follow the service intervals outlined in the owner's manual, which may range from 250 to 500 hours, depending on operating conditions. However, if the excavator is operating in extremely dusty environments or under heavy loads, more frequent filter changes may be necessary.
Example: In a construction project where an excavator is used in dry, dusty conditions, the hydraulic fluid may become contaminated more quickly, necessitating a filter change every 100-150 hours.
Steps to Change the Hydraulic Filter on the E35
Changing the hydraulic filter on the Bobcat E35 is a straightforward process, but it’s important to follow the correct steps to avoid damaging the system. Below is a detailed guide to help you complete the task:
Step 1: Prepare the Excavator

1. Turn Off the Engine: Before starting any maintenance work, ensure the engine is off, and the key is removed.
   
2. Park on Level Ground: Make sure the excavator is on stable, level ground to avoid any risk of the machine shifting during the process.
   
3. Relieve Pressure: To avoid any hydraulic fluid from spilling or creating pressure buildup, relieve pressure in the system by activating the joystick controls a few times while the engine is off.
   

Step 2: Locate the Hydraulic Filter

1. Access the Filter Housing: On the Bobcat E35, the hydraulic filter is typically located near the hydraulic reservoir. You may need to open the access panel or hood to reach the filter housing.
   
2. Identify the Filter: The filter should be clearly labeled. Ensure you have the correct replacement filter that matches the specifications of your machine.
   

Step 3: Remove the Old Hydraulic Filter

1. Drain the Fluid (Optional): If you want to replace the hydraulic fluid as well, you can drain it by loosening the drain plug on the reservoir. However, if you’re only changing the filter, proceed with caution to avoid unnecessary fluid loss.
   
2. Loosen the Filter: Use an appropriate filter wrench to loosen the hydraulic filter. Depending on the design, some filters may be hand-tightened, while others will require a wrench. Turn counterclockwise to remove the filter.
   
3. Check for Leaks: Before removing the filter completely, make sure the area around the filter is clean and dry to prevent contamination.
   

Step 4: Install the New Hydraulic Filter

1. Lubricate the O-Ring: Apply a small amount of clean hydraulic fluid to the O-ring on the new filter. This ensures a proper seal and prevents the O-ring from sticking when tightening.
   
2. Screw in the New Filter: Install the new filter by hand, turning it clockwise. Once the filter is snug, tighten it with the filter wrench, but avoid overtightening, as this can damage the filter or housing.
   
3. Check for Leaks: After installation, visually inspect the area to ensure that no leaks are present around the filter.
   

Step 5: Refill and Check the Hydraulic Fluid

1. Refill the Reservoir (If Necessary): If you drained the hydraulic fluid, refill the hydraulic reservoir with the recommended type and amount of fluid.
   
2. Start the Engine: Turn the excavator on and let it idle for a few minutes to circulate the new fluid.
   
3. Check the Fluid Level: With the engine running, check the hydraulic fluid level using the dipstick. Add more fluid if necessary, but avoid overfilling the reservoir.
   

Step 6: Test the System

1. Operate the Machine: Test the hydraulic system by moving the boom, arm, and bucket. Listen for any unusual sounds, and check for smooth operation. If the system is sluggish or unresponsive, there may be air trapped in the system or the fluid level may be low.
   

Tip: If the system is unresponsive or shows signs of poor performance, perform a "burp" by operating the controls in cycles to help purge air from the hydraulic lines.
Best Practices for Hydraulic System Maintenance
To extend the life of your hydraulic system and avoid frequent filter changes, consider the following best practices:

1. Check the Fluid Regularly: Regularly monitor the condition of your hydraulic fluid. If the fluid appears dirty or contains visible contaminants, it may be time to change both the fluid and filter.
   
2. Avoid Contamination: When adding or changing hydraulic fluid, always use clean tools and containers to prevent introducing dirt or debris into the system.
   
3. Monitor Operating Conditions: Be mindful of the environment in which the machine operates. If the excavator is exposed to extreme conditions, such as dust or heavy workloads, it may require more frequent filter changes.
   
4. Use Quality Fluids and Filters: Always use the manufacturer's recommended hydraulic fluid and filters to ensure compatibility and optimal performance.
   

Example: A contractor working in a demolition site found that the hydraulic filter on their E35 became clogged after just 200 hours of operation, mainly due to dust and debris. They switched to a higher-quality filter designed for extreme conditions, which extended the time between changes significantly.
Common Problems and Solutions

1. Clogged Filters: Over time, filters can become clogged with debris, reducing hydraulic performance.
   • Solution: Regularly change the filter at the recommended intervals and check for fluid contamination.
     
2. Hydraulic Leaks: If a new filter doesn’t seal properly, or if the O-ring is damaged, hydraulic fluid may leak from the filter.
   • Solution: Ensure the O-ring is properly lubricated before installation and check for tightness.
     
3. Slow Hydraulic Response: If the hydraulic system is slow or unresponsive after a filter change, air may be trapped in the system.
   • Solution: Cycle the hydraulic controls several times to purge air from the system.
     

Conclusion: Keeping Your Bobcat E35 in Top Shape
Maintaining the hydraulic system on your Bobcat E35 is essential for ensuring its longevity and optimal performance. By following a simple yet effective maintenance schedule, including changing the hydraulic filter every 50 hours and regularly monitoring the hydraulic fluid condition, you can prevent costly repairs and downtime.
With proper care, your mini excavator will continue to perform efficiently, saving you time and money while providing reliable service on every job. Whether you're working on construction, landscaping, or demolition projects, a well-maintained hydraulic system ensures that your machine operates smoothly and efficiently.