Hydraulic Bleeding in the 1985 Case 855C Track Loader

[MikePhua]

The 1985 Case 855C track loader is a reliable piece of equipment designed to handle tough construction and material handling tasks. However, like all heavy machinery, it can sometimes experience issues with its hydraulic system. One common problem operators face is air or contamination in the hydraulic lines, which can lead to poor performance or even complete failure of the hydraulic components. This article explores the causes and solutions for hydraulic bleeding issues in the Case 855C and provides a guide to addressing these problems efficiently.
Understanding the Hydraulic System of the Case 855C
The hydraulic system in the Case 855C is responsible for driving the loader’s primary functions, including lifting, tilting, and digging. It is powered by a hydraulic pump, which draws fluid from the reservoir and forces it through various hydraulic lines to operate the loader’s attachments. The system is designed to be closed, meaning that the hydraulic fluid should remain contained within the lines and components.
Air, contamination, or moisture in the hydraulic fluid can lead to significant performance issues. When air enters the hydraulic lines, it causes the fluid to become aerated, reducing the system’s pressure and efficiency. This can result in slower response times, jerky movements, or complete failure to perform the required tasks. As such, bleeding the hydraulic system is often necessary to restore optimal performance.
Causes of Hydraulic Bleeding Issues
Several factors can lead to the need for hydraulic bleeding in the Case 855C track loader. Understanding these causes is critical for preventing future problems.

1. Air in the Hydraulic System
   Air can enter the hydraulic system through leaks in the seals, fittings, or hoses. This air reduces the system’s pressure, making the hydraulic components less effective. Leaks are often caused by worn or damaged seals, which may result from regular wear and tear or exposure to harsh operating conditions.
   Common Signs of Air in the System:
   • Slow or unresponsive hydraulic movements
     
   • Jerky or uneven motion of the loader’s arms or attachments
     
   • Unusual noises, such as a hissing or bubbling sound, coming from the hydraulic components
     
2. Contamination of Hydraulic Fluid
   Contaminants like dirt, metal shavings, or moisture can enter the hydraulic system and disrupt the flow of fluid. These particles can cause excessive wear on the hydraulic pump, valves, and cylinders, leading to poor performance and possible damage to critical components.
   Common Sources of Contamination:
   • Worn or damaged seals and gaskets
     
   • Contaminated hydraulic fluid due to improper storage or handling
     
   • Inadequate filtration or a clogged filter system
     
3. Low or Incorrect Hydraulic Fluid Levels
   Hydraulic fluid plays a vital role in maintaining the correct pressure and flow in the system. If the fluid levels are too low, the system will not operate as efficiently, and air can enter the lines. Similarly, using the wrong type of hydraulic fluid can lead to similar performance issues.
   Symptoms of Low Fluid Levels:
   • Reduced lifting capacity
     
   • Sluggish or erratic movement of the loader’s arms or attachments
     
   • Difficulty maintaining hydraulic pressure
     
4. Worn Hydraulic Components
   Over time, the hydraulic pump, valves, and cylinders can wear out. If any of these components are failing, they may allow air into the system, or they may not be able to maintain the correct pressure or fluid flow. This can lead to performance issues that require hydraulic bleeding to resolve.
   

Steps for Bleeding the Hydraulic System
When air or contamination enters the hydraulic system of the Case 855C, bleeding the system is necessary to restore normal operation. The following steps outline the process of bleeding the hydraulic system:

1. Turn Off the Engine and Check Fluid Levels
   Before starting the bleeding process, ensure the engine is turned off, and the loader is on a flat, stable surface. Check the hydraulic fluid levels and top them off if necessary. Ensure the fluid is of the correct type and meets the specifications for the 855C.
   
2. Inspect for Leaks
   Examine the hydraulic hoses, fittings, and seals for any signs of leaks. If you find any, replace the damaged parts to prevent air from entering the system again.
   
3. Locate the Bleed Ports
   On the Case 855C, the hydraulic system will have bleed ports located on the cylinders or valves. These ports allow the air to escape from the hydraulic lines when the system is under pressure. Refer to the operator's manual for the exact location of the bleed ports on your machine.
   
4. Open the Bleed Ports
   Attach a suitable hose or collection container to the bleed port to catch any excess fluid. Slowly open the bleed port, allowing the air to escape. You may need to operate the loader’s hydraulic controls (e.g., raise and lower the arms or tilt the bucket) to help expel the air.
   
5. Close the Bleed Ports
   Once the air has been expelled and only fluid flows from the bleed ports, close them tightly. Be sure not to over-tighten the ports, as this can damage the threads or cause leaks.
   
6. Test the Hydraulic System
   After bleeding the system, start the engine and operate the loader’s hydraulic functions to ensure they are working smoothly. If the system still exhibits signs of air or contamination, repeat the bleeding process or check for additional leaks.
   

Preventative Measures for Hydraulic System Health
To prevent future hydraulic bleeding issues and ensure the longevity of your Case 855C track loader’s hydraulic system, consider the following maintenance practices:

1. Regularly Inspect Hydraulic Components
   Periodically inspect the hydraulic hoses, fittings, seals, and components for wear and tear. Replace any damaged or worn parts promptly to prevent leaks and contamination.
   
2. Change Hydraulic Fluid Regularly
   Hydraulic fluid should be changed according to the manufacturer's recommended schedule or sooner if it becomes contaminated. Use the proper type and grade of fluid to ensure optimal performance.
   
3. Clean or Replace Hydraulic Filters
   The filters in the hydraulic system should be cleaned or replaced regularly to prevent contaminants from entering the fluid. A clogged filter can restrict fluid flow and cause overheating or damage to the system.
   
4. Monitor Fluid Levels and Quality
   Regularly check the hydraulic fluid levels and ensure they are at the correct level. If the fluid appears dirty or milky (which indicates contamination or moisture), it should be replaced immediately.
   

Conclusion
Hydraulic bleeding is a critical procedure for maintaining the performance of the Case 855C track loader. Air, contamination, and low fluid levels are common causes of hydraulic system failure, but with regular maintenance and proper hydraulic bleeding, these issues can be easily addressed. By following the recommended procedures and taking preventative measures, operators can keep their equipment running smoothly and extend its lifespan. Always refer to the operator’s manual for specific instructions and specifications, and ensure that all repairs and maintenance are performed by qualified professionals to avoid further complications.