Section V. EXHAUST SYSTEM
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
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
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
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.