10-22-2025, 06:30 PM
Fiat-Allis FL5 Track Loader Overview
The Fiat-Allis FL5 is a compact track loader introduced in the late 1970s and produced through the 1980s, designed for grading, loading, and light dozing. It features a four-cylinder diesel engine producing approximately 70 horsepower, a mechanical transmission, and a sealed undercarriage. With an operating weight of around 14,000 pounds and a bucket capacity of roughly 1.25 cubic yards, the FL5 was widely adopted in North America and Europe for small construction and agricultural tasks.
Fiat-Allis was a joint venture between Fiat of Italy and Allis-Chalmers of the United States, formed in 1974. The company produced a range of earthmoving equipment until the early 1990s, when it was absorbed into Fiat-Hitachi. The FL5 remains in service today among owner-operators and restoration enthusiasts due to its mechanical simplicity and durable design.
Final Drive Maintenance and Fill Plug Access
The final drive on the FL5 is a sealed gear reduction unit located at each track. It contains gear oil that must be checked and replaced periodically to ensure proper lubrication and prevent wear. Accessing the oil level requires removing the fill plug, which is recessed and secured with an Allen bolt.
Operators often encounter difficulty identifying the correct Allen wrench size for this plug, especially when the original tool is missing or the bolt head is worn. The fill plug is typically located on the side of the final drive housing and may be obscured by dirt or paint.
Confirmed Allen Bolt Size
Field experience and technician reports confirm that the fill plug on the FL5 final drive uses a ¾-inch Allen bolt. This size corresponds to a ¾-inch hex key or Allen wrench, which is larger than most standard sets and may require a specialty tool or socket adapter.
Terminology Notes
In Kansas, a contractor restoring an FL5 for farm use struggled to remove the fill plug using a standard Allen set. After trying several sizes, he discovered that a ¾-inch hex socket fit perfectly. He later fabricated a custom T-handle wrench for future service. The final drive oil was low and dark, prompting a full flush and refill with 80W-90 gear oil. The loader returned to service with noticeably smoother track operation.
Recommendations for Owners
The fill plug on the Fiat-Allis FL5 final drive requires a ¾-inch Allen wrench for removal. This detail, though minor, is essential for proper maintenance and longevity of the track system. With the right tools and attention to oil condition, the FL5 can continue performing reliably in grading and loading tasks for years to come.
The Fiat-Allis FL5 is a compact track loader introduced in the late 1970s and produced through the 1980s, designed for grading, loading, and light dozing. It features a four-cylinder diesel engine producing approximately 70 horsepower, a mechanical transmission, and a sealed undercarriage. With an operating weight of around 14,000 pounds and a bucket capacity of roughly 1.25 cubic yards, the FL5 was widely adopted in North America and Europe for small construction and agricultural tasks.
Fiat-Allis was a joint venture between Fiat of Italy and Allis-Chalmers of the United States, formed in 1974. The company produced a range of earthmoving equipment until the early 1990s, when it was absorbed into Fiat-Hitachi. The FL5 remains in service today among owner-operators and restoration enthusiasts due to its mechanical simplicity and durable design.
Final Drive Maintenance and Fill Plug Access
The final drive on the FL5 is a sealed gear reduction unit located at each track. It contains gear oil that must be checked and replaced periodically to ensure proper lubrication and prevent wear. Accessing the oil level requires removing the fill plug, which is recessed and secured with an Allen bolt.
Operators often encounter difficulty identifying the correct Allen wrench size for this plug, especially when the original tool is missing or the bolt head is worn. The fill plug is typically located on the side of the final drive housing and may be obscured by dirt or paint.
Confirmed Allen Bolt Size
Field experience and technician reports confirm that the fill plug on the FL5 final drive uses a ¾-inch Allen bolt. This size corresponds to a ¾-inch hex key or Allen wrench, which is larger than most standard sets and may require a specialty tool or socket adapter.
Terminology Notes
- Final Drive: A gear reduction assembly that transmits power from the transmission to the tracks.
- Fill Plug: A threaded port used to add or check lubricant in a sealed component.
- Allen Bolt: A bolt with a recessed hexagonal socket head, requiring an Allen wrench for removal.
- Clean the Plug Area Thoroughly: Use a wire brush and solvent to remove dirt and rust before attempting removal.
- Use a Socket-Style Allen Wrench: A ¾-inch hex socket on a breaker bar provides better leverage and reduces the risk of rounding the bolt.
- Check for Thread Sealant: Some plugs may be sealed with thread compound; apply heat if necessary to loosen.
- Inspect Oil Level and Condition: Oil should reach the bottom of the fill port and appear clean. Milky or metallic oil indicates contamination or wear.
In Kansas, a contractor restoring an FL5 for farm use struggled to remove the fill plug using a standard Allen set. After trying several sizes, he discovered that a ¾-inch hex socket fit perfectly. He later fabricated a custom T-handle wrench for future service. The final drive oil was low and dark, prompting a full flush and refill with 80W-90 gear oil. The loader returned to service with noticeably smoother track operation.
Recommendations for Owners
- Keep a Dedicated ¾-Inch Hex Tool: Store it with the machine for easy access during service.
- Service Final Drives Every 500 Hours: Check oil level and condition to prevent gear damage.
- Use High-Quality Gear Oil: Choose oil rated for extreme pressure and temperature stability.
- Document Maintenance Intervals: Track service history to anticipate future repairs.
The fill plug on the Fiat-Allis FL5 final drive requires a ¾-inch Allen wrench for removal. This detail, though minor, is essential for proper maintenance and longevity of the track system. With the right tools and attention to oil condition, the FL5 can continue performing reliably in grading and loading tasks for years to come.
