Solving Persistent Overheating in the International 175C Track Loader

[MikePhua]

When the Temperature Rises but the Workload Doesn’t
The International Harvester 175C track loader, powered by the DT466B diesel engine, is a rugged machine built for clearing, grading, and pushing heavy material. Yet even this proven workhorse can suffer from chronic overheating—especially when age, debris, and neglected cooling systems converge. One operator reported temperatures climbing past 230°F during light-duty log pushing, despite replacing the thermostat and confirming accurate readings with an infrared thermometer.
This kind of thermal behavior suggests a deeper issue than just a faulty gauge or clogged fins. It’s a classic case of airflow restriction, coolant inefficiency, and possibly impeller degradation—all common in older machines.
Radiator Cleaning Requires More Than Air
Compressed air is useful for daily dust removal, but once overheating begins, deeper cleaning is essential. Radiators and oil coolers often trap fine debris—dust, chaff, and oil mist—between their layers. Over time, this forms a thermal blanket that blocks airflow. Even if the fins look clean from the outside, the internal passages may be clogged.
To restore cooling efficiency:

• Soak the radiator with warm water and mild detergent (e.g., dish soap)
  
• Use a garden hose to rinse thoroughly from both sides
  
• Avoid drying between rinses—keep the core wet until clean
  
• Shine a light through the radiator to check for clear airflow
  

One technician noted that removing the radiator entirely revealed a thick mat of debris between the core and oil cooler—something invisible during surface cleaning.
Fan Belt and Impeller Checks
A tight fan belt doesn’t guarantee proper function. Glazed belts can slip under load, reducing fan speed and airflow. Replace any belt showing shine or cracking. Also inspect the water pump impeller—a worn or corroded impeller may spin but fail to circulate coolant effectively. This is especially true in older DT466B engines where impeller blades can erode over time.
Coolant Concentration and Heat Transfer
Coolant that’s too concentrated can hinder heat transfer. A 50/50 mix of antifreeze and water is ideal. Pure concentrate feels thicker and may retain heat instead of dispersing it. Check the coolant’s specific gravity and adjust as needed. An oily sheen on the surface is normal and not a cause for concern unless accompanied by sludge or discoloration.
Thermal Mapping for Diagnosis
To pinpoint the problem:

• Measure temperature at the thermostat housing, radiator inlet, and water pump inlet
  
• Compare readings when the engine exceeds 210°F
  
• Look for large temperature drops or spikes that suggest flow restriction
  

If the radiator inlet is significantly cooler than the thermostat housing, coolant may be stalling or bypassing. If all readings are high, airflow is likely the issue.
Historical Context and Machine Legacy
The International 175C was introduced in the 1970s as a successor to the 175B, offering improved hydraulics and a more powerful engine. The DT466B, with its 466 cubic inch displacement, became a staple in IH’s medium-duty lineup. Though production ceased decades ago, thousands remain in service, especially in rural and forestry applications.
One operator recalled renting a 175C in the early 1980s for land clearing in Georgia, praising its torque and stability. But even then, overheating was a known issue—often resolved by aggressive radiator cleaning and belt replacement.
Conclusion
Overheating in the 175C is rarely caused by a single fault. It’s a layered problem involving airflow, coolant quality, belt condition, and pump efficiency. With thorough cleaning, careful thermal mapping, and attention to belt and impeller health, this classic track loader can return to reliable operation—even under the heat of heavy work.