Michigan 175GM Loader Identification and Transmission Fluid Selection

[MikePhua]

The Michigan 175GM and Its Industrial Legacy
The Michigan 175GM wheel loader is a product of the Clark Equipment Company, a manufacturer that shaped the American heavy equipment landscape throughout the 20th century. Founded in Michigan in the early 1900s, Clark became known for its rugged wheel loaders, forklifts, and construction machinery. The 175GM was part of the GM-powered series, with the “GM” suffix denoting its use of a Detroit Diesel engine—typically a supercharged V8 two-stroke, such as the 6V-71 or 8V-71.
These machines were built for bulk material handling in quarries, logging yards, and municipal operations. With an operating weight exceeding 30,000 pounds and a bucket capacity of around 4 cubic yards, the 175GM was designed for high-cycle loading and long service intervals. Its robust frame, planetary axles, and torque converter transmission made it a favorite among operators who valued mechanical simplicity and brute strength.
Model Identification and Serial Number Decoding
Identifying a Michigan 175GM loader involves locating the serial number plate, typically mounted on the engine hood or inside the cab near the operator’s seat. Serial numbers often begin with a prefix like “8AHG” followed by a numeric sequence. The suffix “IIIA” or “3A” refers to the series revision, indicating updates in hydraulic layout, cab design, or drivetrain configuration.
Key identifiers:

• “175GM” = 175 series with General Motors Detroit Diesel power
  
• “IIIA” = Third major revision of the model
  
• “8AHG” prefix = Clark’s internal designation for production batch
  
• Serial number location = Right side of seat base or engine cover
  

Operators restoring vintage units often rely on archived manuals from MinnPar or aftermarket suppliers, as factory support ceased after Clark’s acquisition by Volvo in the mid-1980s.
Transmission Fluid Type and Seasonal Considerations
The transmission in the 175GM is typically a Clark powershift unit, using a torque converter and planetary gear sets. Fluid selection is critical for maintaining shift quality, cooling, and clutch longevity.
Common fluid options:

• Type F or Dexron ATF (Automatic Transmission Fluid)
  • Offers good cold-weather performance
    
  • Compatible with older seals and friction materials
    
  • May shear under high-load conditions
    
• SAE 10W engine oil
  • Used in warmer climates or high-load applications
    
  • Provides better film strength and thermal stability
    
  • May cause sluggish shifts in cold weather
    
• Synthetic hydraulic-transmission blends
  

• Enhanced oxidation resistance and viscosity index
  
• Longer service intervals and better flow at low temperatures
  
• Higher cost but reduced wear over time
  

Terminology Note: “Shear stability” refers to a fluid’s ability to maintain viscosity under mechanical stress. “Torque converter” is a fluid coupling that transmits engine power to the transmission without direct mechanical contact.
In Maine, where winters are harsh, operators often prefer ATF for its cold-start properties. However, in quarry operations in Arizona, SAE 10W oil is favored for its heat resistance and load-carrying capacity.
Fluid Change Procedure and Inspection Tips
To change transmission fluid:

• Locate the drain plug beneath the transmission pan
  
• Remove fill cap and dipstick (usually right of the seat)
  
• Drain fluid completely and inspect for metal particles
  
• Replace filter element if equipped
  
• Refill with recommended fluid to dipstick mark
  
• Run engine and cycle through gears to purge air
  
• Recheck level and top off as needed
  

Inspection tips:

• Milky fluid may indicate water contamination
  
• Burnt smell suggests overheating or clutch wear
  
• Foaming indicates aeration or overfill
  
• Metal flakes point to gear or bearing damage
  

A technician in Ontario discovered milky red fluid in a 175GM transmission and traced it to a cracked cooler line allowing coolant ingress. After flushing and replacing the line, the transmission returned to normal operation.
Parts Sourcing and Restoration Advice
While Michigan loaders are no longer in production, parts can be sourced through:

• MinnPar (legacy Clark parts distributor)
  
• Salvage yards specializing in vintage equipment
  
• Custom fabrication for brackets, bushings, and seals
  
• Detroit Diesel suppliers for engine components
  
• Hydraulic shops for hose and valve replacements
  

Restoration recommendations:

• Replace all fluids and filters before first use
  
• Inspect wiring harnesses for age-related cracking
  
• Rebuild hydraulic cylinders with modern seals
  
• Upgrade lighting and operator seat for safety
  
• Document serial numbers and modifications for future reference
  

In 2023, a restorer in Wisconsin rebuilt a 175GM for use in a sawmill yard. He replaced the transmission fluid with synthetic blend, added LED work lights, and fabricated a new cab door using original hinge geometry.
Conclusion
The Michigan 175GM loader remains a testament to American industrial engineering—durable, powerful, and mechanically honest. Identifying the correct model variant and selecting the right transmission fluid are essential steps in preserving its performance. Whether operating in snow-covered yards or sunbaked quarries, this machine continues to serve with grit and grace. In the world of vintage iron, the 175GM is more than a loader—it’s a legacy on wheels.