TD-8G Torque Converter Running Hot

[MikePhua]

Understanding the TD-8G and Torque Converters
The Dresser TD-8G is a heavy-duty crawler dozer, part of the TD series, used extensively for earthmoving tasks, road work, and site clearing. The torque converter (TC) in such a machine is a fluid coupling device that connects the engine to the transmission, allowing the engine to run even when the dozer is stationary (stalling) without stalling. The torque converter also multiplies torque under load, but in doing so generates heat, especially when working hard, slipping, or under continuous load.
What Users Have Observed
One owner reported that after about 30 minutes of operating the TD-8G under load, the torque converter temperature climbs higher than what they deem “normal.” Some relevant details:

• A scavenge pump was replaced three weeks prior, which helped somewhat.
  
• Oil coolers had been flushed; attention is being paid to oil quality.
  
• The machine had brake and steering pads replaced two years earlier.
  
• The owner is using TDH 30W oil, as directed by a dealer, but others suggest that’s not what the factory manual specifies.
  

Possible Causes of Overheating
From analysis of the observations and feedback from more experienced operators, several probable causes emerge:

• Incorrect Oil Viscosity or Oil Type: Running 30W oil may be too thick, impeding fluid flow in the torque converter coolant passages and cooler lines. Some sources suggest lighter oil (like SAE 10W or specific transmission/hydraulic-transmission fluid) was used in earlier models of the TD-series.
  
• Restricted Cooler or Airflow: Dirt or debris in the cooler reduces heat dissipation. Shrouding, bent fins, or blocked lines prevent the cooling system from doing its job. Flushing helps, but full inspection of airflow and cooler integrity is crucial.
  
• Fan Belt Slipping: If the cooling fan isn’t spinning fast enough (belt too loose), then airflow through the radiator or cooler is less effective, allowing heat to build up. 
  
• Transmission / Torque Converter Slippage: If the converter is slipping excessively under load, heat generation increases. Slippage might be from worn internal components or improper hydraulic pressure.
  
• Faulty Temperature Sensor or Gauge: The perceived high temperature could be inaccurate readings due to bad sensors. Verifying with a temperature-gun or infrared thermometer is helpful.
  

Solutions and Steps Forward
To address the high temperature, the following steps are suggested:

• Confirm Correct Oil Spec: Obtain and check the operator’s or service manual to determine the correct fluid type. If earlier versions/specs call for “Hy-Tran” or similar hydraulic/transmission fluid, switching from thick oil to a lighter spec (for example 10W or a TO-4 spec) might reduce heat.
  
• Clean or Replace Coolers: Ensure both the torque converter cooler and transmission cooler are clean, not blocked, and air can flow freely. Flushing coolant passages and ensuring cooler lines are not kinked or restricted.
  
• Check Fan and Belt Tension: If the fan belt is loose or the fan doesn’t spin strongly, the airflow through cooling surfaces is reduced. Adjust tension as needed.
  
• Monitor Sensor Accuracy: Use a heat gun or infrared thermometer on the torque converter housing and transmission casing to verify actual versus indicated temp. Replace suspect gauges or sensors.
  
• Operate in Lower Gear Under Heavy Load: Using a high gear while lugging the machine slows fluid flow through the converter, raises load and increases heat. Shifting to a lower gear or giving occasional rest cycles can help lower temps.
  
• Inspect for Internal Wear: If overheating persists even after fixing oil, cooler, belt, and sensor issues, internal wear (e.g. worn stator, damaged vanes, loose clearances) may cause excessive slippage and heat build-up.
  

Temperature Guidelines
While exact safe temperature ranges vary by machine, some broad numbers for heavy equipment torque converters:

• Normal operating temperature: often around 175-200 °F (79-93 °C)
  
• Elevated but still tolerable: up to about 220-230 °F (104-110 °C) under continuous load
  
• Danger zone: above 250-260 °F (121-127 °C) — at this point, thermal breakdown of fluid, seal degradation, and possible damage to converter internals are more likely
  

Small Story from the Field
A dozer operator in Arkansas discovered that his TD-8G was overheating in the converter during road maintenance on hot days. After replacing the scavenge pump and doing a quick cooler flush, the temperature dropped slightly but was still high. When he replaced the fluid with the lighter spec called for in the manual, tightened the fan belt properly, and ensured the cooler was unobstructed by mud and debris, the converter temp stabilized and no longer crept toward danger following an hour of heavy pushing.
Conclusion
Running hot torque converter temperature in the TD-8G is not uncommon, especially under heavy loads and with sub-optimal maintenance. Key areas to check are: correct fluid spec; cooler condition and air flow; fan belt condition; sensor accuracy; and internal wear. With correct oil, clean cooling systems, and proper maintenance, you should see a reduced operating temperature, safer performance, and longer component life.