Troubleshooting the Mustang 960 Tandem Pump: Common Issues and Solutions

[MikePhua]

The Mustang 960 is a versatile and reliable skid steer loader used in construction, landscaping, and various other industries. One of the critical components of this equipment is the tandem pump — a hydraulic system that powers multiple functions within the skid steer, such as the lifting arm, bucket, and auxiliary hydraulic lines. However, like any other complex hydraulic system, the tandem pump can encounter issues over time. This article delves into the workings of the Mustang 960 tandem pump, common problems, diagnostic methods, and effective solutions.
What is a Tandem Pump?
A tandem pump is a type of hydraulic pump commonly used in heavy equipment like the Mustang 960. It consists of two or more pumps mounted on a common shaft, allowing for the simultaneous operation of multiple hydraulic functions. In the Mustang 960, the tandem pump powers the main hydraulic functions, such as lifting the boom, tilting the bucket, and operating attachments.
The tandem pump ensures that different hydraulic circuits can be powered without the need for multiple individual pumps. This setup makes the system more efficient and compact, providing a seamless flow of hydraulic power to various components.
Common Problems with the Mustang 960 Tandem Pump
While the tandem pump in the Mustang 960 is designed to be durable and efficient, there are a few common issues that may arise over time. Here are the primary concerns operators face:

1. Hydraulic Power Loss
   One of the most common issues with the tandem pump is a noticeable loss of hydraulic power. This can manifest in several ways:
   • Slow or Weak Lift: The loader arms and bucket may operate slower than usual, or they may not lift as much weight as they should.
     
   • Inconsistent Hydraulic Functions: Other attachments or hydraulic functions may work intermittently or with less power than expected.
     
   Possible Causes:
   • Low Hydraulic Fluid Levels: If the hydraulic fluid is low, the pump may not be able to generate sufficient pressure to power the system.
     
   • Clogged Filters: A clogged hydraulic filter can restrict fluid flow, reducing the efficiency of the tandem pump.
     
   • Pump Wear: Over time, the internal components of the tandem pump, such as pistons and seals, can wear out, causing reduced efficiency.
     
2. Contaminated Hydraulic Fluid
   Hydraulic fluid is the lifeblood of the pump, providing the necessary pressure to operate the system. However, contamination is a common issue that can affect the performance of the tandem pump.
   Possible Causes:
   • Dirty Fluid: If the hydraulic fluid is contaminated with dirt, water, or debris, it can cause premature wear on the pump’s internal components.
     
   • Broken Seals: Damaged seals can allow contaminants to enter the hydraulic system, causing further damage to the pump.
     
   Symptoms:
   • Unusual noises coming from the pump or hydraulic system.
     
   • Reduced efficiency or response time from hydraulic functions.
     
3. Leaking Hydraulic Lines or Fittings
   Hydraulic fluid leaks can significantly impact the performance of the tandem pump. Leaks may occur at various points in the system, including hydraulic lines, fittings, or the pump itself.
   Possible Causes:
   • Loose or Damaged Fittings: Over time, fittings and connections may loosen, causing hydraulic fluid to leak.
     
   • Worn Seals or O-Rings: Seals and O-rings within the pump can wear out, leading to leaks and reduced performance.
     
   • Cracked Lines: Hydraulic lines can develop cracks due to pressure or external damage, leading to fluid loss.
     
   Symptoms:
   • Visible hydraulic fluid around the pump or hydraulic lines.
     
   • A significant drop in hydraulic pressure.
     
4. Noisy Tandem Pump
   A tandem pump should operate relatively quietly under normal conditions. However, when there is an issue, it may start to make unusual noises, such as whining, grinding, or cavitation sounds.
   Possible Causes:
   • Air in the System: Air pockets in the hydraulic system can cause cavitation, which leads to a distinctive whining noise.
     
   • Worn Pump Components: If the pump’s internal components, such as gears or pistons, are worn out, they can cause grinding or knocking noises.
     
   Symptoms:
   • Loud or irregular noises emanating from the pump during operation.
     
   • The system may also feel “jerky” or erratic in its performance.
     
5. Erratic Hydraulic Functioning
   Erratic or unpredictable hydraulic functioning is another issue that can arise with the tandem pump. For example, the boom or bucket may move too quickly or too slowly, or the system may have difficulty maintaining consistent speed or power.
   Possible Causes:
   • Valve Malfunctions: A faulty control valve can cause erratic flow to hydraulic components, leading to unpredictable operation.
     
   • Pump Cavitation: If the pump is sucking in air, it can cause the hydraulic fluid to foam, resulting in poor pump performance.
     
   Symptoms:
   • Inconsistent lifting or bucket movement.
     
   • Jerky or sudden movements when the hydraulics are engaged.
     

Troubleshooting the Mustang 960 Tandem Pump
When troubleshooting issues with the Mustang 960 tandem pump, it’s essential to follow a structured diagnostic approach. Here’s a step-by-step process for identifying and resolving common issues:

1. Check Hydraulic Fluid Levels
   • Inspect the hydraulic fluid reservoir and ensure the fluid is at the correct level.
     
   • If fluid is low, top up with the recommended hydraulic oil.
     
   • Check for signs of contamination, such as discoloration or a burnt smell. Replace the fluid if necessary.
     
2. Inspect Hydraulic Filters
   • Check the hydraulic filters for clogs or damage. If the filters are dirty, replace them with new ones to ensure proper fluid flow.
     
   • Clean the filters regularly as part of a preventive maintenance routine to avoid future blockages.
     
3. Look for Leaks
   • Inspect the hydraulic lines, fittings, and the pump itself for signs of leaks.
     
   • Tighten any loose connections, and replace damaged seals, O-rings, or lines as needed.
     
4. Test the Pump
   • If the pump is suspected to be worn or damaged, it may need to be tested for performance. This can be done by measuring the hydraulic pressure at various points in the system.
     
   • Compare the measured pressures to the specifications in the Mustang 960 service manual.
     
5. Check for Air in the System
   • To check for air in the system, perform a bleeding process. This involves loosening the hydraulic fittings slightly to allow air to escape, then re-tightening them.
     
   • If air is entering the system, inspect the pump seals and hoses for damage.
     
6. Inspect the Control Valves
   • If the hydraulic system is erratic, inspect the control valves for proper operation. A malfunctioning valve can lead to inconsistent hydraulic flow.
     
   • Repair or replace faulty valves as needed.
     

Preventive Maintenance for the Mustang 960 Tandem Pump
Maintaining the tandem pump is key to extending the life of the Mustang 960 skid steer. Here are some preventive maintenance tips:

1. Regularly Check Hydraulic Fluid Levels and Quality
   • Ensure the hydraulic fluid is at the correct level and that it remains clean. Change the fluid regularly according to the manufacturer’s recommendations.
     
2. Inspect and Replace Filters
   • Hydraulic filters should be checked and replaced regularly to avoid system contamination. Replace filters whenever the fluid is changed.
     
3. Lubricate Moving Parts
   • Ensure that all moving components of the tandem pump are well-lubricated. Check for any signs of wear or corrosion.
     
4. Monitor for Leaks
   • Routinely inspect the hydraulic system for leaks. Address any leaks immediately to prevent fluid loss and pressure drops.
     
5. Test Hydraulic Pressure
   • Regularly test the hydraulic system’s pressure to ensure the pump is performing optimally. This can help identify issues early before they cause significant damage.
     

Conclusion
The tandem pump in the Mustang 960 skid steer plays a vital role in powering the hydraulic system and enabling the loader to perform its various functions. Understanding the common problems, symptoms, and troubleshooting steps for the tandem pump is essential for maintaining the equipment's performance and reliability. Regular inspections, fluid changes, and prompt repairs are necessary to keep the pump functioning optimally, minimizing downtime and maximizing productivity. By adhering to a comprehensive maintenance routine and addressing issues early, operators can ensure the longevity and efficient operation of their Mustang 960 skid steer.