🔍 Key Concepts

• combustion quality in diesel engines • difference between fuel-related vs oil-related exhaust smoke colors • what black smoke typically indicates compared to blue or white smoke

💭 Think About

• Think about what happens if there is more fuel than air can burn completely inside a diesel cylinder. • Recall the usual color of exhaust when an engine is burning lube oil instead of just fuel. • Consider whether water in the fuel would make the exhaust darker, lighter, or more steamy-looking.

✅ Before You Answer

• Match smoke color (black, blue, white) with the most common cause in diesel engines. • Ask: Does this condition point to too much fuel, too little air, or contamination like water? • Eliminate any option that would more likely cause no smoke or light/white smoke rather than dark, sooty exhaust.