🔍 Key Concepts

• Crankcase pressure – what causes gases to enter the crankcase instead of staying in the cylinder • The normal path of combustion gases past the piston and rings • Difference between compression, lube oil, scavenge air, and blow‑by in a diesel engine

💭 Think About

• Think about which condition would let high‑pressure combustion gases escape from the cylinder into the crankcase space • Which of the listed pressures is actually connected to the crankcase volume, and which are in completely separate systems? • Consider what happens when piston rings or cylinder sealing are no longer doing their job effectively

✅ Before You Answer

• Identify which listed pressures are not normally routed to the crankcase at all • Recall that crankcase pressure rise usually comes from leakage of combustion gases during the power stroke • Verify which option directly describes gases passing the piston rings into the crankcase