Practice question

Blue-gray smoke from the exhaust of a school bus diesel, most noticeable at startup and during deceleration, MOST likely indicates:

  1. Engine oil being burned in the combustion chamber
  2. Coolant leaking into a cylinder
  3. Excessive fuel delivery at idle
  4. A plugged air filter

Answer: A — Engine oil being burned in the combustion chamber

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Practice more: ASE S2 Diesel Engines (School Bus) Practice Questions - ASE S2 - Diesel Engines (School Bus) Certification Exam →