🔍 Key Concepts

• Blow-by in a diesel engine means combustion gases leaking past the piston rings into the crankcase • Piston rings must move freely in their grooves to maintain a tight seal against the cylinder wall • Causes of blow-by are usually things that reduce the rings’ ability to seal (wear, damage, or sticking)

💭 Think About

• Look at each option and ask: does this directly affect how well the piston rings can seal against the cylinder liner? • Which choice would physically keep the ring from expanding out to contact the cylinder wall properly? • Which options are more like general engine conditions (temperature, scavenging, design features) rather than a specific fault at the ring/cylinder interface?

✅ Before You Answer

• Verify which option describes something happening right at the piston ring and groove area • Eliminate choices that mainly affect air flow or exhaust but not the ring’s sealing action • Focus on the choice that would most likely cause the ring to stick or not move freely in its groove