Getting Started with the International TD-15C Dozer Practical Knowledge for New Owners

[MikePhua]

The TD-15C’s Legacy and Mechanical Identity
The International Harvester TD-15C crawler dozer was introduced in the late 1970s and remained in production into the early 1980s. It was part of the long-running TD series, which began in the 1930s and helped define mid-size dozer performance across North America. The TD-15C was powered by the DT-466 turbocharged diesel engine—a robust inline-six known for its torque and reliability. This engine later became a staple in agricultural and vocational trucks, further cementing its reputation.
The TD-15C was designed for land clearing, grading, and general earthmoving. With an operating weight of around 35,000 lbs and a blade capacity of 9.5 cubic yards, it offered a balance of power and maneuverability. Though no longer manufactured, thousands of units were sold, and many remain in service today on farms, construction sites, and private properties.
Basic Fluid Systems and Service Points
New owners often face confusion when locating and identifying service points. Here’s a breakdown of key systems and their maintenance needs:

• Transmission dipstick: Located under the operator’s seat; use SAE 30 or TO-4 spec transmission fluid
  
• Hydraulic tank: Integrated with the diesel fuel tank on some models; typically uses 10W hydraulic oil
  
• Hydraulic filter: Often mounted externally near the tank or pump; check for spin-on or cartridge type
  
• Final drives: Use SAE 90 gear oil; fill and check via plugs on the outer hubs
  
• Engine oil: Twin spin-on filters mounted vertically on the right side of the DT-466; change every 150 hours
  
• Fuel filters: Dual filters on the left side of the engine; replace every 250 hours or if fuel delivery drops
  

One common concern is the orientation of the engine oil filters. Though mounted with threads downward, they are designed to retain oil internally due to anti-drainback valves. This prevents dry starts and ensures consistent lubrication.
Track Adjustment and Greasing
Track tension is maintained via a grease-filled hydraulic cylinder behind the front idler. To tighten:

• Locate the grease zerk on the track adjuster (usually behind a protective plate)
  
• Pump grease until the track sag is reduced to 1–2 inches between the carrier roller and top of the track
  
• To release tension, remove the zerk and allow grease to escape slowly
  

Over-tightening can accelerate wear on pins and bushings, while under-tightening risks derailment. A good rule is to check tension weekly during active use and after any track-related maintenance.
Engine Swap Considerations
Some TD-15C units have been retrofitted with newer versions of the DT-466 or even non-OEM engines. When swapping engines, ensure compatibility with:

• Bellhousing and transmission input shaft
  
• Cooling system routing and radiator capacity
  
• Electrical harness and gauge cluster
  
• Exhaust routing and turbo orientation
  

In one Arkansas farm case, a retired firefighter installed a DT-466 turbo engine into his TD-15C. After minor modifications to the mounts and exhaust, the machine ran smoothly and gained noticeable torque improvement during land clearing.
Locating Manuals and Technical Resources
Finding a service manual for the TD-15C can be challenging. While International Harvester was absorbed into Case IH in the mid-1980s, many technical documents remain in circulation through:

• Equipment salvage yards
  
• Online auction platforms
  
• Collector forums and restoration groups
  

If a full manual is unavailable, engine-specific documentation for the DT-466 can provide valuable torque specs, fluid capacities, and wiring diagrams. Additionally, parts catalogs from similar models like the TD-15E or TD-15M may offer interchangeable references.
Practical Advice for New Operators
Operating a TD-15C requires attention to mechanical feedback and terrain awareness. Tips for smoother operation include:

• Warm up the engine and hydraulics for 10–15 minutes before heavy work
  
• Avoid sudden directional changes under load to protect the transmission
  
• Use blade float mode when grading loose material
  
• Inspect undercarriage weekly for wear on rollers, idlers, and sprockets
  
• Keep the battery box and electrical connections dry and clean
  

In one restoration story, a user fabricated missing battery box covers using 12-gauge steel and added rubber seals to prevent moisture intrusion. This simple upgrade prevented electrical shorts and extended battery life.
Conclusion
The International TD-15C remains a capable and respected machine decades after its production ended. For new owners, learning its systems and quirks is part of the journey. With a solid understanding of fluid types, service intervals, and mechanical layout, even first-time operators can keep their dozer running strong. Whether clearing land, building roads, or restoring vintage iron, the TD-15C offers a hands-on education in durability and design.