1935 Cadillac - GM Heritage Center

119
EXHAUST SYSTEM
General Description
The arrangement of the exhaust system differs
on the various type engines. On the Cadillac V-8
the exhaust manifolds are connected at the top to
the manifold header to which is connected a single
exhaust pipe leading to the muffler.
The exhaust gases pass from the cylinders
through the manifolds to the header and out
through the exhaust pipe. The flow of hot gases
through the header heats the fuel mixture quickly
to assist in more thorough vaporization of the fuel.
Two entirely separate exhaust systems are used
on both the Cadillac 370-D and 452-D, one system
for each block of cylinders. Each of these exhaust
systems includes an exhaust manifold, an exhaust
pipe, a muffler and a tail pipe.
The 370-D exhaust manifold is in two sections
and the 452-D manifold is in three sections to
allow for expansion. These sections are connected
by tight fitting leak-proof sleeves.
The front section of the 370-D exhaust manifold
carries the upper part of the intake header.
The center section of the 452-D manifold contains
part of the heat chamber for heating the
gases passing from the carburetor to the intake
manifold.
The LaSalle manifolds are constructed with a
heater body to provide a by-pass for the exhaust
gases around a portion of the inlet manifold, to
insure a more nearly uniform vaporization of the
fuel mixture especially when the engine is cold.
The flow of exhaust gases through the heater
body is regulated by a thermostatically controlled
heater valve. Two thermostat springs are used
to control the action of the heater valve, and hold
the valve closed under pressure when the manifold
is cold, thereby diverting the exhaust gases
around the inlet manifold. With the manifold
cold (65 to 70° F.) and the heater valve closed,
each spring should have % to % of a turn
wind up. As the manifold becomes hot, the
heater valve automatically opens and permits the
exhaust gases to pass directly into the exhaust pipe
and muffler.
The exhaust pipes on the Cadillac cars are
covered with a heavy asbestos insulation to prevent
excessive heat under the hood and in the
body, and to muffle the exhaust noises.
Cadillac mufflers have an asbestos lining between
two shells which are welded together at
the ends. The purpose of the asbestos lining is to
deaden or muffle the exhaust noises. This lining
also serves as a heat insulator and less heat is
dissipated under the body. Rubber cushions, are
used between the muffler support brackets and
the frame on all models to prevent the exhaust
vibrations being transmitted to the body.
In addition to the muffler on the Cadillac cars,
a silencing chamber, consisting of a piece of pipe
about two feet long, is mounted above and connected
near the rear end of the tail pipe. This
chamber acts on the same principle as the tuning
chamber in the carburetor air silencer.
The mufflers on the Series 30, 40 and 60 cars are
mounted on the outside of the frame to permit a
more rigid frame construction. On the remaining
Series cars, the muffler is mounted inside of the
frame in the conventional way.
Service Information
1. Crackling Noises in Manifolds
Some V-16 engines when new, give out a crackling
noise after a long run when the ignition is shut
off. This noise will be heard only in some new
engines and is caused by the contraction of the
manifold sections as the exhaust manifolds cool.
This condition will not injure the engine and is
automatically eliminated after the manifolds and
blocks have taken a permanent set.
To correct this condition smooth up the faces
and corners of the manifold flanges with emery
paper and spread thinly a paste made up of
graphite and oil, over the contacting surfaces.
Finally pull up the flange nuts tightly but without
excessive strain.
2. Installing Exhaust Manifold Gaskets
Exhaust manifolds are subject to such extreme
variations in temperature that the metal expands
and contracts to a considerable degree. This
results in "creeping" on the manifold gaskets
which has no undesirable effect unless the bolts
are drawn up too tight.
The manifold bolts should be tightened while
the engine is running and should be drawn up
just enough to stop all exhaust leaks. If the bolts
are tightened too securely, the "creeping" of the
manifold may rip the copper of the gasket and
permit the gasket to burn out.
The possibility of V-12 and V-16 intake and
exhaust gaskets blowing out can be greatly
reduced by coating them with graphite before
installing. Coating the gaskets with graphite
makes it easier for the manifold to expand and
contract without pulling or wrinkling the gasket
which may in some cases cause the gasket to
blow out.