🔍 Key Concepts

• four-stroke diesel starting requirements (compression, temperature, fuel, timing) • effects of low vs. high compression on ignition of diesel fuel • how leakage past rings/valves changes compression and starting behavior

💭 Think About

• In a diesel, what actually ignites the fuel, and which option would most directly prevent that from happening even if fuel pressure and cranking speed are normal? • Which choices describe conditions that might let the engine still run once started, versus a condition that would stop it from starting at all? • For each option, ask: does this make the air in the cylinder hotter or cooler during compression?

✅ Before You Answer

• Review that diesel ignition depends on high compression temperature, not a spark plug. • Consider how air leakage past piston rings or valves affects compression pressure and temperature. • Check which options would tend to lower effective compression temperature instead of raising it.