Figure 7-2. Exhaust Manifold

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Chapter 7. EXHAUST AND EMISSION CONTROL SYSTEMS

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TM-9-8000 Principles of Automotive Vehicles Manual

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Figure 7-3. Manifold Heat Control Valve

TM 9-8000

Figure 7-2. Exhaust Manifold

A typical muffler has several concentric

economy and also cause overheating.

chambers with openings between them. The gas enters

the inner chamber and expands as it works its way

e. Exhaust system components usually are made

through a series of holes in the other chambers and

of steel. They usually are coated with aluminum or zinc

finally to the atmosphere.

to retard corrosion. Stainless steel also is used in

exhaust systems in limited quantities due to its high cost.

d. Mufflers must be designed to quiet exhaust noise

A stainless steel exhaust system will last indefinitely.

while creating a minimum of back pressure. This could

cause loss of engine power and

Section II. EMISSION CONTROL SYSTEMS

however, this is not what happens. The fuel never

7-5. Purpose (Fig. 7-5). When the fuel is burned In the

combines completely with the oxygen and undesirable

combustion chamber, the ideal situation would be to

exhaust emissions are created as a result. The major

have the fuel combine completely with the oxygen from

pollutants are:

the intake air. The carbon would then combine to form

carbon dioxide (COI, the hydrogen would combine to

a. Carbon Monoxide (CO). Carbon monoxide is

form water (H20), and the nitrogen that is present In the

formed as a result of insufficient oxygen in the

intake air would stand alone. The only other product

mixture

and

chamber

present in the exhaust would be any oxygen from the

temperatures that are too low. Carbon monoxide Is a

intake air that was not used in the burning of the fuel. In

colorless, odorless gas that is poisonous

a real life situation

TA233470

7-2