MUFFLER CONSTRUCTION, OPERATION AND CARE
The muffler was designed to silence the otherwise loud report of the
exploding charge of gas, which is released from the cylinders by the
sudden opening of the exhaust valves.
While these devices are differently shaped and formed, the functional
purpose and action is practically the same in all designs.
The burnt or inert gases are forced from the cylinders on the exhaust
stroke. It passes into the exhaust manifold which absorbs some of the
heat before it reaches the muffler.
[Illustration:
Hanger
Tie Rod
Split Clamp Nut
Muffler Shell
Spacer
Spacer
Nozzle
Center Pipe
Fig. 48. Muffler--Three Compartment]
Fig. 48 shows a three compartment muffler. The burnt gases enter
compartment No. 1 from the exhaust pipe. This compartment is
sufficiently large to spread the volume which lessens the pressure and
force. It then enters the rear compartment No. 3, through the center
pipe; it expands again and passes through the perforated spacer plate,
enters compartment No. 2, and escapes through the nozzle in an even
silent flow.
The muffler at all times produces a certain amount of back-pressure on
the engine which results in a slight loss of power. The back pressure
exerted by the majority of mufflers, however, is very slight and has a
tendency to counter balance or equalize the sudden shock delivered to
the bearings by the explosion over the piston head.
The muffler may also become fouled by the use of too much or too heavy
a grade of lubricating oil, which will cause the expansion space and
the small holes in the spacer plates to become clogged with carbon
and soot. This carbon and soot soon bakes into a hard crust causing
much back pressure which results in a considerable loss of power. This
condition will become noticeable first by a loss of considerable power
caused by an overheated motor. If this condition is not remedied, the
exhaust manifold and pipe leading to the muffler will soon become
red-hot, causing much danger of a serious damage loss to the car from
fire.
[Illustration: Fig. 49. Muffler]
=Muffler.=--To eliminate or remedy this condition, disconnect manifold
pipe from the muffler, remove the muffler from hangers, and disassemble
it by removing the nuts from the tie rods which release the end plates.
This will allow the compartment walls and spacer plates to be drawn
from the sleeve. Each compartment and spacer plate should be removed
sectionally, and its position carefully noted, in order that it may
be replaced correctly in re-assembling. The walls of the sleeve, and
the compartment end plates are scraped and rubbed with a piece of
sandpaper. A small round file may be used in cleaning the center pipe.
The spacer plates are scraped and sandpapered. The small holes in
the spacer plates may be opened by using the tapered end of a small
file. Fig. 49 shows a muffler of another design. The burnt gas enters
a compartment containing three saucer shaped spacers which retard and
break up the volume. It then passes through an open compartment and
enters reversed spacers through small holes near the sleeve wall. It
centers or forms slightly in volume and escapes to the next compartment
through a small hole in the center of the second spacer. This action of
forming and breaking is kept up until the outlet is reached.