🔍 Key Concepts

• Blow-by in a diesel engine means combustion gases leaking past the piston into the crankcase • Ring clearances control how well piston rings seal against the cylinder wall and in their grooves • Think about which type of clearance would most directly affect how tightly the ring seals around the circumference of the cylinder

💭 Think About

• Which ring clearance would most affect the ability of combustion pressure to escape between the ends of the ring vs. between the ring and its groove? • How does excessive clearance in the ring groove (up/down or in/out) compare with excessive clearance at the ring ends for allowing gas to pass into the crankcase? • Visualize the ring in the cylinder: if it wears in one particular dimension, where would hot gases most easily find a path around it?

✅ Before You Answer

• Identify which option refers to the clearance between ring ends rather than between the ring and the groove surfaces • Confirm which type of clearance change would open a continuous path for gases all the way around the piston • Eliminate any clearances that mainly affect ring stability or movement in the groove but not the basic circumferential seal against the cylinder wall