Chapter 18 Diagnosis and Repair of the Emission Control and Exhaust Systems 397
Copyright by Goodheart-Willcox Co., Inc.
Exhaust System Components
Components in the exhaust system are relatively easy
to replace. The vehicle should be on a lift to gain enough
clearance to maneuver the pipes. Replacement of exhaust
manifolds and gaskets are discussed in Chapter 19.
Warning: Always wear eye protection when
working on an exhaust system. The system
contains large amounts of loose rust that
will dislodge when the system is disturbed.
The exhaust system is attached to the underbody of the
vehicle by fl exible hangers. The hangers allow the exhaust
piping to move with the engine. Most exhaust pipes slip
together and are sealed by special clamps called saddle
clamps, or simply muffl er clamps.
Some pipes have fl anges that match a fl ange on the
mating pipe. Flanges are tightly held together by fl ange col-
lars and bolts. Some fl anges use a gasket between the mating
surfaces. See Figure 18-38. Other fl anges are bell-mouthed
and do not use a gasket. Bell-mouthed fl anges usually use
separate collars on each pipe to allow the fl anges to mate
closely with each other at any angle. Flanges are often used
to connect the exhaust pipes to the exhaust manifold.
To begin replacing exhaust system components,
remove the exhaust hangers that hold the sections to be
replaced. Then, loosen and remove the pipe fasteners.
If the fasteners are badly corroded, cut them off using a
power cutting wheel, chisel, or torch. Since exhaust clamps
are subjected to extreme heat and corrosive elements, it
is recommended that the new clamps be used instead of
reinstalling the old clamps.
Note: Use generous amounts of penetrating
oil on all exhaust system fasteners. The
fasteners will likely be hard to remove.
Removing Fitted Exhaust Components
When removing pipes that slip together, carefully cut
or chisel the defective pipe or component from the pipe
that is to be reused. Heat from a torch can also be used, if
carefully applied. If the pipe to be replaced is the outside
pipe, split the pipe down the entire length of the joint using
a chisel. Then, twist the outer pipe and pull it from the inner
pipe. If the pipe to be replaced is the inside pipe or the joint
is welded, use an exhaust pipe cutter to cut the pipe off
just before the joint with the outside pipe. Then, split and
collapse the inner pipe inward using a curved chisel. When
the inner pipe is collapsed enough, twist and pull it from
the outer pipe with a pair of adjustable pliers.
Warning: If a torch is used to heat or cut off
an exhaust system part, be careful not to
apply heat to the underside of the vehicle.
The heat from the torch could start a fi re inside of
the vehicle. Do not use a torch near the fuel tank,
fuel fi lter, or fuel lines. Once a part has been heated,
use heavy gloves or pliers to touch or grab the part.
When installing slip-fi t pipes and components, it may
be necessary to expand the old pipe. This can be done by
using an exhaust-pipe-expansion tool. Slip the new part onto
or into the exhaust system and install new clamps. Tighten
the clamp at about the midpoint on the sleeve where the
two parts meet. Once installed, reinstall the exhaust system
on the vehicle along with any heat shields and other parts
that were removed. Finally, road test the vehicle, making
sure that no part of the exhaust system rattles against the
body or heat shield.
Note: While it is not necessary in most
cases, some technicians will place one or
more spot welds on the edge of an exhaust
slip joint. This ensures that the two parts will not
slip and come apart with movement of the exhaust
system.
Figure 18-38. Flanged connections allow for movement between
fi xed and moving parts. The connection between the exhaust
manifold and exhaust pipe is almost always a fl anged connec-
tion. (Toyota)
Exhaust gas flow
Exhaust pipe
Ball-shaped
joint
Spring
Flange
Gasket
Bolt
Exhaust manifold