Troubleshooting Tandem Pump Issues in Bobcat 1835C

[MikePhua]

When operating machinery like the Bobcat 1835C skid steer loader, reliability is paramount. A significant component in ensuring this reliability is the tandem pump, which plays a key role in delivering hydraulic power for various functions of the machine. However, like any mechanical part, tandem pumps can sometimes run into issues, which can significantly impact the loader's performance.
In this article, we’ll dive into the tandem pump issues often experienced by Bobcat 1835C operators, how to troubleshoot these problems, and share tips on maintaining hydraulic systems to prevent failures. Understanding these common problems and solutions will ensure you can keep your equipment running smoothly and efficiently.
What is a Tandem Pump in Bobcat 1835C?
A tandem pump is a type of hydraulic pump that combines two pumps into one unit. In the case of the Bobcat 1835C, the tandem pump is responsible for supplying hydraulic fluid to power the loader’s various systems, including the lift arms, bucket, auxiliary hydraulics, and steering. These pumps operate in tandem—one pump powers the lift and tilt function, while the other drives the auxiliary hydraulics.
Because of their crucial role, issues with the tandem pump can lead to a range of symptoms, including:

• Loss of lifting power
  
• Slow bucket or lift arm operation
  
• Weak auxiliary hydraulics
  
• Uneven or unresponsive steering
  

Let’s explore these issues in more detail and how they can be resolved.
Common Tandem Pump Problems in the Bobcat 1835C

1. Loss of Hydraulic Pressure
   • Symptom: If you notice that the lift arms or auxiliary hydraulics are slow to respond or struggle to reach full pressure, there’s a chance the tandem pump is not delivering adequate hydraulic pressure.
     
   • Cause: The tandem pump may be worn out, or the check valve or relief valve may be malfunctioning. In some cases, air can enter the hydraulic system, causing cavitation and a drop in pressure.
     
   • Solution: Check the fluid levels and ensure that there is no air in the system. Inspect the relief valve and check valve for damage or wear. If the pump is worn, it may need to be replaced or rebuilt.
     
2. Erratic or Uneven Steering
   • Symptom: If the steering of the Bobcat 1835C becomes jerky, difficult, or unresponsive, this could indicate a problem with the tandem pump. The uneven steering can make the loader hard to control, especially in tight spaces.
     
   • Cause: A failure in the steering hydraulic circuit or a malfunctioning tandem pump may result in the inability to provide consistent hydraulic flow to the steering mechanism.
     
   • Solution: Inspect the hydraulic lines for leaks and blockages. Ensure that the fluid is clean and at the proper level. If necessary, test the tandem pump output to ensure it’s providing steady pressure to the steering system.
     
3. Overheating
   • Symptom: Overheating is another common issue associated with a failing tandem pump. If the system is overheating, it can lead to premature wear of the hydraulic components, including the tandem pump itself.
     
   • Cause: Overheating may be caused by restricted fluid flow or contaminated fluid. The tandem pump may be working harder than normal, causing excess heat.
     
   • Solution: Check for any restrictions in the hydraulic system, including clogged filters or lines. Inspect the cooler to ensure it’s functioning properly. If the fluid is contaminated, perform a fluid flush and replace the filter.
     
4. Noise from the Tandem Pump
   • Symptom: Unusual noises, such as whining or grinding sounds, coming from the hydraulic pump are common indicators that something is wrong.
     
   • Cause: These noises can be a result of cavitation, air in the hydraulic system, or internal wear within the pump. If the pump is not getting enough fluid, it may produce cavitation, which can cause permanent damage over time.
     
   • Solution: Ensure that the hydraulic fluid is at the proper level and free of air bubbles. If the noise persists, consider having the tandem pump inspected for internal damage or wear.
     

How to Maintain the Tandem Pump on a Bobcat 1835C
Maintaining the tandem pump is crucial for ensuring long-term reliability and optimal performance of the Bobcat 1835C. Here are some essential maintenance tips:

1. Regular Fluid Checks: Make sure the hydraulic fluid is at the correct level and replace it according to the manufacturer’s recommended schedule. Low or dirty fluid can cause wear on the tandem pump and other hydraulic components.
   
2. Check for Leaks: Inspect the hydraulic lines, seals, and fittings regularly to ensure there are no leaks. Even small leaks can lead to significant loss of hydraulic pressure and affect the performance of the tandem pump.
   
3. Change Filters Frequently: Clogged filters can restrict fluid flow and cause cavitation in the hydraulic system. Replace the hydraulic filters at the intervals recommended in the Bobcat 1835C service manual.
   
4. Monitor Operating Temperature: Keep an eye on the operating temperature of the machine. Excessive heat can cause the fluid to break down, leading to damage in the tandem pump. Ensure that the cooler is functioning and that the fluid is not overheating.
   
5. Flush the System: Periodically flushing the hydraulic system can remove contaminants and ensure that the system operates efficiently. This helps prevent damage to the tandem pump and other hydraulic components.
   

Replacing the Tandem Pump on the Bobcat 1835C
If you determine that the tandem pump is indeed faulty and needs to be replaced, it’s crucial to follow the correct procedures to avoid causing damage to the hydraulic system. Here’s a brief overview of the steps involved:

1. Drain Hydraulic Fluid: Before replacing the tandem pump, drain the hydraulic fluid from the system to prevent spills and contamination.
   
2. Remove the Old Pump: Disconnect the hydraulic lines from the tandem pump and remove any bolts securing the pump to the frame. Take care to note the orientation of the pump for proper reinstallation.
   
3. Install the New Pump: Install the new tandem pump in the same orientation and reconnect the hydraulic lines. Ensure that the pump is properly aligned and securely fastened.
   
4. Fill with Fresh Fluid: After installing the new pump, refill the hydraulic system with fresh fluid. Bleed the system to remove any air trapped in the lines.
   
5. Test the System: Once the new tandem pump is installed, run the machine and test the hydraulic system to ensure everything is working correctly. Check for leaks and monitor the system’s performance.
   

Conclusion: Ensuring Optimal Performance of the Bobcat 1835C Tandem Pump
The tandem pump in the Bobcat 1835C plays an essential role in the loader's overall hydraulic performance. Addressing issues like low pressure, steering difficulties, or overheating early on can prevent costly repairs and downtime. By staying on top of regular maintenance and being proactive about troubleshooting potential problems, operators can extend the life of the tandem pump and keep their Bobcat 1835C performing at its best.