Black Smoke, Cause, Impact, and Prevention We have all seen
clouds of black smoke emanating from the exhaust stacks of heavy
duty diesel trucks especially when the truck is under high load
or hard acceleration. The black smoke is composed primarily of
elemental carbon from incomplete combustion of diesel fuel and
traces of engine lubricant. The exhaust of a typical diesel
engine contains elemental carbon (soot), semi-volatile organic
hydrocarbons, sulfates (primarily sulfuric acid), and water
vapor. Elemental carbon which is black is formed for a wide
range of reasons when the diesel fuel charge in the combustion
cylinder is incompletely combusted. Incomplete combustion occurs
and soot is formed when there is an over abundance of fuel (both
diesel fuel and lube oil), insufficient residence time in the
combustion zone, and/or non-availability of sufficient oxidants.
Over-fueling is the primary cause of black smoke from the
exhaust of a heavy duty diesel engine. Over-fueling can be
caused by diesel fuel injecto