🔍 Key Concepts

• Exhaust smoke color as an indicator of what’s happening inside the cylinder • How lubricating oil, fuel, and water each tend to burn (or not burn) in a diesel engine • Typical causes of blue vs. black vs. white exhaust in diesel engines

💭 Think About

• Ask yourself: What substance, when it gets into the combustion space and partially burns, commonly produces a bluish haze in the exhaust? • Which of the listed faults would most likely allow that substance to enter the cylinder or combustion space? • Which choices are more closely linked to different smoke colors (for example, heavy fuel, unburned fuel, or steam)?

✅ Before You Answer

• Distinguish between oil burning, unburned fuel, and water/steam effects in the exhaust • Consider which defect could let lubricating oil pass into the combustion chamber • Eliminate any option that is more typically associated with black smoke (over-fueling/poor combustion) or white smoke/steam (water or cold combustion) rather than blue smoke