🔍 Key Concepts

• Blow-by is combustion gas leaking past the piston rings into the crankcase • How piston rings seal: contact with the cylinder wall, the ring groove, and the end gap • Which clearance change would give gases a direct path around the ring

💭 Think About

• Picture the ring sitting in its groove inside the cylinder: where could an increase in clearance let gases leak most easily? • Which type of clearance (back, side, gap, bottom) would most directly affect how tightly the ring seals against the cylinder wall? • Think about which clearance is specifically controlled to limit how much opening exists when the ring expands with heat.

✅ Before You Answer

• Review what ring end clearance (also called ring gap) means versus side and back clearance • Consider which clearance is most critical for sealing pressure rather than just allowing ring movement and lubrication • Eliminate any choice that mainly affects how the ring moves in the groove rather than how gases can flow around its ends.