Section V. EXHAUST SYSTEM

3-15. DESCRIPTION

control valve in the exhaust line is open, the suction

created by the venturi action sucks water into the

a. General. The exhaust system consists of a muffler

pump body, and when it is filled, into the suction line.

which connects to the manifold piping of the engine,

The water which is sucked through the suction line

and an exhaust primer which mounts on top of the

is discharged through the primer. This indicates that

muffler.

the pump body is full and that additional priming is

not required. The exhaust primer control valve is

b . Muffler. The muffler helps reduce engine exhaust

then closed and the exhaust primer lever operated to

noise. It consists of a sheetmetal cylinder which

remove the cap from the top of the exhaust primer

contains baffles around which exhaust gases must

and to allow the exhaust gases to be discharged

circulate before they are dispelled to atmosphere.

through the exhaust port at the top of the body without

This system tends to equalize the pressures at which

restriction. The exhaust primer control valve should

the exhaust is released, resulting in a noise reduction.

remain closed until the next time priming is required.

c . Exhaust Primer. When the exhaust primer is not

3-16. MUFFLER AND EXHAUST PRIMER

operating, exhaust gases from the muffler are directed

through the exhaust port at the top of the priming

--. Removal and Disassembly.

valve body with little restriction. To operate the

primer, the exhaust primer lever is positioned so

(1) Refer to figure 3-8 and remove the muffler and

that a cap seals the exhaust port at the top of the

exhaust primer.

valve body. This forces the exhaust gases through a

venturi system at the side of the valve body. As the

(2) Refer to figure 3-9 and disassemble the muffler

gases pass through the venturi, their speed is highly

and exhaust primer as necessary to replace de-

accelerated. Suction is created as the gases rush past

fective parts.

a port just beyond the restricted area of the venturi.

A vacuum line connects this port and a port at the

top of the pump housing. When the exhaust primer

Figure 3-9. Muffler and exhaust primer,

Figure 3-8. Muffler and exhaust primer,

disassembly and reassembly.

removal and installation.

3-9