Bobcat 773 Auxiliary Hydraulics: How to Clean the Coil Stem

[MikePhua]

The Bobcat 773, a compact skid steer loader, is a versatile piece of equipment commonly used in a variety of industries such as construction, landscaping, and material handling. One of the key features of this machine is its auxiliary hydraulic system, which powers various attachments, such as augers, breakers, and grapple buckets. However, like any hydraulic system, regular maintenance is crucial to ensure optimal performance.
One common issue that owners may encounter is a dirty or clogged auxiliary hydraulic coil stem. This can result in poor attachment performance, leaks, or even damage to the system if left unchecked. This article provides a detailed guide on how to clean the coil stem of the Bobcat 773's auxiliary hydraulics, covering the symptoms, tools, and techniques needed to perform this task.
Understanding the Auxiliary Hydraulic System
The auxiliary hydraulic system on the Bobcat 773 allows the machine to power attachments independently of the main hydraulic system. The system includes hydraulic hoses, valves, and a coil stem that facilitates fluid flow to the attachment. The coil stem, specifically, is a component that connects the hydraulic lines to the attachments, and it can become clogged over time due to dirt, debris, or the accumulation of hydraulic fluid contaminants.
Signs of a Clogged or Dirty Coil Stem
A clogged or dirty coil stem can lead to several issues with the auxiliary hydraulic system. Some common signs that it may be time to clean the coil stem include:

1. Weak or Slow Attachment Operation: If the attachment is operating at a reduced speed or with reduced power, it could be a sign that the hydraulic fluid is not flowing properly due to a clog in the coil stem.
   
2. Fluid Leaks: A clogged or damaged coil stem may cause hydraulic fluid to leak, resulting in a loss of pressure in the system and the potential for further damage.
   
3. Uneven or Jerky Movement of Attachments: If the attachment moves erratically or jerks during operation, it could indicate that the hydraulic system is not functioning smoothly due to a restriction in the flow.
   
4. No Response from Attachment: In some cases, the attachment may fail to respond at all, which can occur if the coil stem is completely blocked or if the hydraulic system is starved of fluid.
   

Tools and Materials Needed for Cleaning the Coil Stem
Before beginning the cleaning process, it's essential to gather the necessary tools and materials. Here's a list of items you’ll need:

1. Wrench Set: To remove the coil stem and hydraulic lines.
   
2. Rags or Shop Towels: For cleaning up hydraulic fluid spills and wiping down components.
   
3. Hydraulic Fluid: Fresh hydraulic fluid to replace any that might have been lost during the cleaning process.
   
4. Solvent or Degreaser: A non-corrosive cleaning agent to break down contaminants within the coil stem.
   
5. Compressed Air: To blow out debris and dry the components after cleaning.
   
6. Rubber Gloves: To protect your hands from hydraulic fluid and solvents.
   
7. Replacement O-rings or Seals: If necessary, to replace any worn or damaged seals during the process.
   

Step-by-Step Guide to Cleaning the Coil Stem
Now that you have the tools and materials ready, follow these steps to clean the coil stem on your Bobcat 773’s auxiliary hydraulic system.

1. Turn Off the Engine and Relieve Pressure: Before starting any maintenance on hydraulic systems, always ensure the engine is off, and the hydraulic system is depressurized. To do this, engage the auxiliary hydraulic lever to release any stored pressure.
   
2. Locate the Coil Stem and Hydraulic Hoses: The coil stem is typically located near the front of the skid steer, where the hydraulic lines connect to the attachment. You will need to disconnect the hydraulic hoses to gain access to the coil stem. Use a wrench to carefully loosen and remove the hoses from the stem.
   
3. Inspect the Coil Stem: Once the hoses are disconnected, inspect the coil stem for any visible signs of wear, damage, or buildup. Check for cracks, leaks, or debris inside the stem that may be obstructing fluid flow. If there are any damaged components, you may need to replace the coil stem or related parts.
   
4. Clean the Coil Stem: Using a solvent or degreaser, apply it generously to the coil stem to break down any dirt, oil, or hydraulic fluid contaminants. Use a small brush or a soft cloth to scrub the inside of the stem to remove any debris. Be sure to clean the hose fittings and the area surrounding the stem as well.
   
5. Blow Out Debris with Compressed Air: Once the coil stem is cleaned with solvent, use compressed air to blow out any remaining debris or cleaning fluid. This will ensure that the inside of the stem is free from contaminants that could clog the system.
   
6. Inspect and Replace Seals or O-rings: Check the O-rings and seals on the hydraulic hoses and the coil stem for any wear or damage. If necessary, replace the seals with new ones to prevent future leaks. Make sure the new O-rings are properly lubricated before installation to ensure a tight seal.
   
7. Reassemble the Hydraulic System: Once the coil stem is cleaned and all seals are replaced, reconnect the hydraulic hoses to the coil stem. Tighten the fittings securely with a wrench, but be careful not to overtighten, as this could damage the threads or cause leaks.
   
8. Check Fluid Levels: After reassembling the system, check the hydraulic fluid level. If any fluid was lost during the cleaning process, top it off with the appropriate hydraulic fluid for your Bobcat 773.
   
9. Test the Auxiliary Hydraulics: Start the engine and test the auxiliary hydraulic system by operating an attachment. Check for smooth operation and listen for any abnormal sounds. Ensure that the attachment moves freely and with full power.
   

Common Issues and Troubleshooting Tips
While cleaning the coil stem is a straightforward process, there may be some additional challenges or issues that arise during the process. Here are some common problems and solutions:

1. Persistent Leaks: If you notice persistent leaks after reassembling the system, check the O-rings, hose fittings, and the coil stem for any visible damage. A damaged component may need to be replaced.
   
2. Hydraulic Fluid Contamination: If the hydraulic fluid appears contaminated with debris or dirt, it could indicate that there are other issues with the system, such as a failing hydraulic filter. Check and replace the filter if necessary.
   
3. Attachment Not Responding: If the attachment still doesn’t respond after cleaning the coil stem, check the hydraulic fluid levels, the pump, and the control valve to ensure they are functioning correctly. Low fluid or a malfunctioning valve can prevent the hydraulic system from operating properly.
   

Preventive Maintenance for the Auxiliary Hydraulic System
To avoid frequent issues with the auxiliary hydraulics, regular maintenance is key. Here are some tips to help prevent coil stem clogs and ensure the system operates efficiently:

1. Regularly Inspect the Hydraulic System: Periodically check the hydraulic hoses, filters, and coil stem for signs of wear, damage, or contamination. Early detection can prevent larger issues.
   
2. Change Hydraulic Fluid as Needed: Over time, hydraulic fluid can degrade or become contaminated with dirt and debris. Follow the manufacturer’s guidelines for fluid replacement intervals.
   
3. Use Clean, High-Quality Hydraulic Fluid: Always use high-quality hydraulic fluid that meets the specifications for your Bobcat 773. This helps prevent contaminants from entering the system and reduces the likelihood of coil stem clogging.
   
4. Keep the Attachment Area Clean: Keep the area around the auxiliary hydraulic connections free from dirt and debris. Clean the attachment and hydraulic hoses regularly to prevent contaminants from entering the system.
   

Conclusion
Cleaning the auxiliary hydraulic coil stem on a Bobcat 773 is an essential maintenance task to ensure the efficient operation of the machine’s hydraulic system. By following the steps outlined in this guide, you can improve the performance of your attachments, reduce the risk of leaks, and prevent costly repairs. Regular maintenance and attention to detail can extend the lifespan of the auxiliary hydraulic system, allowing your Bobcat 773 to continue performing at its best for years to come.