🔍 Key Concepts

• Exhaust smoke colors and their typical causes in diesel engines • What happens when lubricating oil gets into the combustion chamber • The difference between problems caused by fuel/air vs lubricating oil

💭 Think About

• Which exhaust smoke color is usually linked with unburned fuel, and which is linked with burning engine oil? • If the engine were under a very light load, how would that affect fuel burning and exhaust appearance? • Think about which choice would most likely cause oil to enter the combustion space and partially burn.

✅ Before You Answer

• Match each answer choice to a physical cause that could change exhaust color. • Ask: Does this option relate more to fuel/air mixture or to lubricating oil? • Eliminate any options that do not provide a clear path for oil to reach the combustion chamber and burn.