Operating and Maintaining the Mustang 552 Skid Steer Loader

[MikePhua]

The Mustang 552 and Its Historical Footprint
The Mustang 552 skid steer loader was introduced in the late 1980s as part of Mustang Manufacturing’s push into the mid-frame compact loader market. With a rated operating capacity of approximately 1,500 pounds and an overall weight near 5,500 pounds, the 552 was designed for versatility in construction, landscaping, and agricultural tasks. Powered by a robust 4-cylinder diesel engine—often a Perkins or Continental—the machine featured mechanical controls, chain-driven axles, and a straightforward hydraulic system.
Mustang Manufacturing, founded in 1865 and later acquired by Manitou Group, built its reputation on durable, operator-friendly compact equipment. The 552 was one of its most widely distributed models in North America, with thousands sold before production ended in the mid-1990s. Its simplicity and mechanical reliability have kept many units in service decades later.
Terminology Notes

• ROPS (Rollover Protective Structure): A safety frame designed to protect the operator in case of rollover.
  
• Auxiliary Hydraulics: A secondary hydraulic circuit used to power attachments like augers or trenchers.
  
• Chain Case: The enclosed housing that contains the drive chains connecting the hydraulic motors to the wheels.
  
• Lift Arm Pivot Pins: Structural pins that allow the loader arms to raise and lower while bearing heavy loads.
  

Core Operating Features and Controls
The Mustang 552 uses manual levers for steering and lift functions, with foot pedals controlling bucket tilt and auxiliary hydraulics. Key specifications include:

• Engine power: 40–50 hp depending on variant
  
• Hydraulic flow: Approximately 12–15 GPM
  
• Tire size: 10x16.5 standard
  
• Fuel tank capacity: Around 15 gallons
  
• Lift height: Roughly 9 feet at hinge pin
  

Operators appreciate the machine’s responsive controls and low center of gravity, which provide stability on uneven terrain. A contractor in Alberta used his 552 for snow removal and fence post installation, noting that its mechanical simplicity made it easy to repair in the field.
Maintenance Essentials and Common Issues
Routine maintenance is critical to keeping the 552 reliable. Key service points include:

• Engine oil and filter
  • Change every 100 hours or monthly
    
  • Use SAE 15W-40 for most climates
    
• Hydraulic fluid and filter
  • Replace every 500 hours
    
  • Check for contamination or aeration
    
• Chain case oil
  • Inspect level and condition quarterly
    
  • Use gear oil rated for high-load applications
    
• Lift arm and bucket pivot pins
  • Grease weekly to prevent wear and seizure
    
• Tire pressure and tread
  

• Maintain 45–55 psi depending on load and terrain
  

Common issues include:

• Hydraulic leaks at hose fittings or valve blocks
  
• Chain tension loss due to worn sprockets
  
• Starter motor failure from vibration exposure
  
• Fuel system clogging from sediment in older tanks
  

A technician in Texas rebuilt a 552’s chain case after noticing uneven drive response. He replaced the sprockets, adjusted chain tension, and flushed the case with solvent, restoring full traction.
Manual Availability and Documentation Challenges
Finding original manuals for the Mustang 552 can be difficult due to its age and the company’s ownership changes. Many units were sold without digital documentation, and printed manuals often disappeared over time. Solutions include:

• Contacting Manitou Group for legacy support
  
• Searching equipment archives and dealer networks
  
• Networking with other owners for scanned copies
  
• Visiting vocational schools or libraries with heavy equipment collections
  

Some operators create their own service logs and diagrams based on teardown experience. A crew in British Columbia documented every hydraulic line and electrical wire during a full rebuild, producing a reference binder that now serves as their go-to manual.
Operator Anecdotes and Field Wisdom
A retired operator in Montana recalled using a Mustang 552 to clear brush and dig irrigation trenches. He praised its ability to run all day on a single tank and its resistance to overheating, even in summer heat. After losing the original manual, he reverse-engineered the hydraulic system using colored zip ties and a notebook.
In Maine, a landscaping team used their 552 for hauling mulch and grading driveways. They added a custom-built cab heater and LED work lights, improving winter usability and visibility during early morning starts.
Recommendations for Owners and Restorers
To ensure long-term performance:

• Keep a dedicated binder with service records, part numbers, and diagrams
  
• Replace hydraulic hoses and fittings every 5 years or sooner if cracked
  
• Upgrade lighting and safety features for modern compliance
  
• Use high-quality grease and fluids to reduce wear
  
• Train operators on manual control sensitivity and maintenance routines
  

A restoration shop in Georgia created a Mustang 552 rebuild checklist including engine compression tests, chain case flush, and hydraulic valve calibration. This helped them restore three units to full working order and resell them with confidence.
Conclusion
The Mustang 552 skid steer loader remains a dependable workhorse decades after its release. With mechanical simplicity, solid build quality, and adaptable performance, it continues to serve operators who value reliability over electronics. Whether grading a driveway or clearing a lot, the 552 proves that old iron still earns its keep—and a well-kept manual is worth its weight in diesel.