Practice question

A school bus diesel has excessive crankcase pressure (high blow-by) measured at the oil fill. This MOST likely indicates:

  1. A restricted PCV/crankcase breather only
  2. Worn piston rings, cylinder bore wear, or a failed crankcase ventilation system allowing combustion gases past the rings
  3. A loose serpentine belt
  4. A weak alternator

Answer: B — Worn piston rings, cylinder bore wear, or a failed crankcase ventilation system allowing combustion gases past the rings

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