🔍 Key Concepts

• Oil control in four-stroke diesel engines (compression, power, exhaust, intake strokes) • How lube oil can enter the combustion space (rings vs. valve guides vs. other parts) • Difference between problems that affect combustion quality vs. those that affect oil leakage paths

💭 Think About

• For each choice, ask yourself: does this fault create an easy path for oil to get into the cylinder and be burned? • Which components (rings, cylinder walls, valve guides) are directly involved in sealing and guiding moving parts that are lubricated with engine oil? • Which options mainly affect airflow or combustion rather than providing a direct route for oil to enter the combustion chamber?

✅ Before You Answer

• Identify which option involves parts that are directly lubricated by lube oil and move inside a close-fitting guide or bore • Eliminate choices that mainly cause poor combustion, reduced efficiency, or back pressure but do not normally increase oil flow into the cylinder • Focus on the component that, when worn, allows oil to be drawn or pushed past a seal/clearance into the combustion space during operation