🔍 Key Concepts

• combustion quality vs. exhaust color in diesel engines • effect of fuel viscosity and atomization when heavy fuel oil is too cold • typical meanings of white, black, and blue smoke from a diesel exhaust

💭 Think About

• Think about what happens to heavy fuel oil if it is not heated enough before injection: how does this affect spray pattern and combustion? • Which exhaust color is most commonly linked to incomplete combustion and soot rather than water vapor or burning lube oil? • Match each color (white, black, blue) to its usual cause in marine diesel engines, then decide which cause fits "insufficiently preheated heavy fuel oil."

✅ Before You Answer

• Identify which color is associated with unburned carbon/soot from poor atomization of fuel. • Eliminate the color that is more typical of lube oil burning rather than fuel problems. • Eliminate the color that is usually linked to water vapor/cold engine or misfire rather than heavy fuel being too viscous.