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Class 4 Commercial Driver Practice · Question

What does a continuous cloud of white smoke from the exhaust pipe usually indicate?

White smoke often indicates coolant leaking into the engine, while black smoke indicates too much fuel (running rich). Any unusual smoke should be investigated.

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Question: What does a continuous cloud of white smoke from the exhaust pipe usually indicate?

Answer options: ✅ Coolant leaking into the combustion chamber

  • The engine is running at the correct temperature
  • The air filter is perfectly clean
  • The brakes are overheating

Correct answer: Coolant leaking into the combustion chamber

Explanation: White smoke often indicates coolant leaking into the engine, while black smoke indicates too much fuel (running rich). Any unusual smoke should be investigated.

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