What
Does Colour of Engine Smoke Mean?
The
exhaust emissions of a perfectly tuned engine should be invisible; if the smoke
of the engine is visible then there may be some defect in the engine. The
colour of the engine smoke gives a clue to the possible engine defects. Some of
them are discussed below:-
1. Thin
White Vapours
This
is due to condensation of water vapours inside the exhaust system and may be
accompanied by a slow drip of water. It is perfectly harmless and is often seen
during the starting of the vehicle from cold, in the morning.
2. Thick
Blue or Grey Smoke
This
may be due to the lubricating oil in the crank case reaching and burning in the
combustion chamber. Apart from loss of oil, it can result in fouled spark
plugs, rough idle, hard starting and sluggish acceleration. On turbo charged
engines, bluish- grey smoke may mean failure of the turbocharger.
3. Black
Sooty Smoke
Such
a smoke is usually due to the air- fuel mixture being excessively rich. This
may be due to many factors, e.g. a clogged cleaner, the choke stuck closed, a
faulty sensor, a clogged component in the fuel injection system. The exact
cause will need systematic investigation by a trained mechanic.
4. Thick
White Smoke
This
type of smoke indicates serious trouble and needs immediate attention. It may
be caused by the burning of the coolant in the engine, a damaged cylinder head
gasket, crack in the cylinder block or a damaged cylinder head. Any of these
would require the complete engine overhaul. It is better and safer in such a
case to tow the vehicle to the garage.
