🔍 Key Concepts

• crankcase versus combustion space problems • how blow-by from pistons/rings shows up in the crankcase • which listed faults would put hot gases or oil mist into the crankcase ventilation system

💭 Think About

• Ask yourself: which defect directly lets high‑temperature combustion gases and oil mist pass into the crankcase, where the exhaust fan would then pull them out? • Which of these faults would mainly affect cylinder pressure or cooling, but not necessarily cause smoke specifically at the crankcase fan outlet? • Think about where each fault physically occurs in the engine and whether its symptoms would show up in the crankcase vent or somewhere else (exhaust, cooling system, scavenge ports).

✅ Before You Answer

• Match the symptom location: smoke at crankcase exhaust fan, not at the main exhaust or air intake • Identify which choice most clearly increases blow‑by into the crankcase • Eliminate options that would more likely cause symptoms in the cooling system or exhaust gases instead of the crankcase vent.