Practice question

A viscous (thermal) fan clutch on a school bus diesel does not engage when the engine is hot, causing overheating at idle and low speed. The technician should:

  1. Ignore it because the fan only matters at highway speed
  2. Remove the fan entirely
  3. Test/replace the fan clutch, since at low speed the fan provides most of the airflow for cooling
  4. Add more coolant only

Answer: C — Test/replace the fan clutch, since at low speed the fan provides most of the airflow for cooling

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