system mixes air and fuel to produce a combustible mixture. A large volume of air passes
through the carburetor or fuel injection system and engine, as much as 100,000 cubic feet
of air every 1,000 miles. Air always contains a lot of floating dust and grit. The dust
and grit could cause serious damage if they entered the engine. To prevent this, mount an
air cleaner (fig. 4-14)
at the air entrance of the carburetor or fuel injection system. The two types of cleaners
currently used are the wet and dry types.
wet-type. or oil bath, air cleaner consists of the main body, the filter element that is
made of woven copper gauze, and the cover (fig. 4-15). Operation is
as follows: Incoming air enters between the cover and the main body. The air is pulled
down to the bottom of the main body where it must make a 180-degree turn, as it passes
over the oil reservoir.
the air passes over the oil reservoir, most of the particles will not be able to make the
turn, and they will hit the oil and be trapped.
the air continues upward and passes through the filter element, the smaller particles that
bypassed the oil will be trapped.
air keeps the element soaked with oil by creating a fine spray, as it passes the
air then makes another 180-degree turn and enters the carburetor.
air cleaner passes the incoming air through a filtering medium before it enters the
The air filter
contains a ring of filter material (fine-mesh metal threads or ribbons, pleated paper,
cellulose fiber, or polyurethane), as shown in figure 4-16. These types
of filter materials provide a fine maze that traps most of the airborne particles.
cleaner also muffles the noise of the intake air through the carburetor or fuel injection
system, manifold, and valve ports. This noise would be very noticeable if it were not for
the air cleaner. In addition the air cleaner acts as a flame arrester in case the engine
backfires through the intake manifold. The air cleaner prevents the flame from escaping
and igniting gasoline fumes outside the engine.
4-15.Wet-type air filter.
4-16.Dry-type air filter.