AIR CLEANER

The fuel 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.

• The 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.
• As 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.
• As the air continues upward and passes through the filter element, the smaller particles that bypassed the oil will be trapped.
• The air keeps the element soaked with oil by creating a fine spray, as it passes the reservoir.
• The air then makes another 180-degree turn and enters the carburetor.

The dry-type air cleaner passes the incoming air through a filtering medium before it enters the engine.

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.

The air 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.

Figure 4-14.—Air cleaner.

Figure 4-15.—Wet-type air filter.

Figure 4-16.—Dry-type air filter.