Radiator Maintenance and Replacement on the John Deere 350C Dozer

[MikePhua]

The John Deere 350C and Its Cooling System Design
The John Deere 350C crawler dozer is a compact, versatile machine built for grading, clearing, and light excavation. Introduced in the late 1970s as part of Deere’s evolution from the earlier 350 and 350B models, the 350C featured improvements in hydraulic performance, operator comfort, and cooling efficiency. With a naturally aspirated diesel engine producing around 50 horsepower, the 350C was widely adopted across North America and remains in use today in farms, municipalities, and private fleets.
The cooling system in the 350C is critical to engine longevity and performance. It includes a front-mounted radiator, belt-driven water pump, thermostat housing, and coolant reservoir. The radiator itself is a copper-brass core unit designed to dissipate heat from the engine block through forced airflow and coolant circulation.
Terminology Notes

• Core: The central section of the radiator where coolant flows through tubes and fins for heat exchange
  
• Tank: The upper and lower chambers of the radiator that distribute coolant into the core
  
• Shroud: A protective cover that directs airflow from the fan through the radiator
  
• Coolant Recovery System: A reservoir that captures overflow and returns it to the radiator as needed
  
• Solder Joint: A metal bond used to seal radiator tubes and tanks, prone to fatigue over time
  

Common Radiator Issues and Symptoms
Operators of aging 350C units often encounter radiator problems such as:

• Coolant leaks from the lower tank or solder joints
  
• Overheating during extended operation or high ambient temperatures
  
• Cracked mounting brackets due to vibration
  
• Clogged fins from dust, mud, or vegetation
  
• Reduced coolant flow from internal corrosion or scale buildup
  

One operator in Iowa reported that his 350C began overheating after only 30 minutes of grading. Upon inspection, the radiator core was partially blocked by cottonwood fluff and the lower tank had developed a pinhole leak near the drain plug.
Inspection and Diagnosis
To assess radiator health:

• Check coolant level and color before startup
  
• Inspect for wet spots or dried residue around the core and tanks
  
• Use a pressure tester to identify leaks under operating pressure
  
• Shine a light through the fins to check for airflow obstruction
  
• Monitor engine temperature with an infrared thermometer during operation
  

If coolant is discolored or contains rust particles, it may indicate internal corrosion. A coolant flush and chemical cleaning may restore flow, but severe cases require core replacement.
Repair and Replacement Options
Radiator repair depends on the severity of damage:

• Minor leaks at solder joints can be repaired with silver solder or epoxy
  
• Cracked tanks may be brazed or replaced if compatible parts are available
  
• Fins can be cleaned with compressed air or a soft brush, avoiding high-pressure water that may bend them
  
• Mounting brackets should be reinforced with gussets or rubber isolators to reduce vibration stress
  

For full replacement, aftermarket radiators are available from suppliers specializing in vintage Deere parts. Ensure compatibility by matching:

• Core dimensions (height, width, thickness)
  
• Inlet and outlet hose diameters
  
• Mounting hole locations
  
• Shroud clearance and fan alignment
  

A technician in British Columbia replaced his 350C radiator with a custom-built aluminum unit featuring a high-efficiency core and reinforced tanks. The upgrade reduced operating temperature by 15°F and eliminated recurring leaks.
Preventive Maintenance Recommendations
To extend radiator life:

• Flush coolant every 500 hours or annually
  
• Use a 50/50 mix of ethylene glycol and distilled water
  
• Inspect hoses and clamps monthly
  
• Clean fins after dusty operations
  
• Replace the radiator cap every two years to maintain proper pressure
  

For machines operating in cold climates, consider installing a block heater and using low-temperature-rated coolant to prevent freeze damage.
Stories from the Field
A grading crew in Nebraska used a 350C to build drainage swales on a farm. After noticing steam from the hood, they discovered a cracked lower tank caused by vibration and age. They fabricated a steel brace to support the radiator and installed rubber bushings at the mounts. The fix held for over two seasons without further issues.
In another case, a forestry operator in Maine retrofitted his 350C with a remote coolant sensor and alarm. The system alerted him to rising temperatures before damage occurred, allowing him to shut down and clean the radiator fins during peak pollen season.
Conclusion
Radiator health is essential to the performance and reliability of the John Deere 350C dozer. Whether repairing a leak, replacing a core, or upgrading to modern materials, attention to cooling system integrity ensures the engine runs efficiently and avoids costly downtime. With proper maintenance and thoughtful modifications, even decades-old machines like the 350C can continue working hard in the field.
Sources: Field reports, technical bulletins, and restoration case studies from independent equipment technicians.