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4D
Chapter 4 Part D:
Exhaust and emission control systems
Air inlet heating system components - removal and refitting . . . . . . 4
Catalytic converter - general information and precautions . . . . . . . . 7
Crankcase ventilation system components - removal and refitting . 5
Electro-pneumatic ignition timing retarding system components -
removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Emission control system check . . . . . . . . . . . . . . . . . . . .See Chapter 1
Exhaust manifold - removal and refitting . . . . . . . . . . . . . . . . . . . . . . 3
Exhaust system - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . 2
Exhaust system check . . . . . . . . . . . . . . . . . . . . . . . . . . .See Chapter 1
Fuel vapour recirculation system components - removal and
refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Fluid leaks and hoses check . . . . . . . . . . . . . . . . . . . . . .See Chapter 1
4D•1
Contents
Easy, suitable for
novice with little
experience
Fairly easy, suitable
for beginner with
some experience
Fairly difficult,
suitable for competent
DIY mechanic
Difficult, suitable for
experienced DIY
mechanic
Very difficult,
suitable for expert DIY
or professional
Degrees of difficulty
5
4
3
2
1
1 General information
Exhaust system
1 The exhaust system consists of front,
intermediate and rear sections, the number
varying according to model. The system is
suspended from the underbody on rubber
mountings, and bolted to the exhaust
manifold at the front. Flanged joints
incorporating gasket seals or pipe clamps are
used to secure the sections. The front section
downpipe is of twin, or “siamesed” type and is
attached to the manifold by a flanged joint
incorporating compression springs or by a
single spherical joint. On TU series engines, a
ball-and-socket type joint is provided
between the front downpipe and intermediate
pipes, to allow for engine movement.
2 Later fuel-injected models are equipped
with a catalytic converter as part of the
exhaust emission control system.
Emission control systems
3 Various systems may be fitted to reduce the
emission of unburned hydrocarbons and
harmful exhaust gases into the atmosphere.
Basically, these systems can be divided as
follows:
a) Air inlet heating system.
b) Crankcase ventilation system.
c) Electro-pneumatic ignition timing
retarding system.
d) Catalytic converter.
e) Fuel vapour recirculation system.
4 The operation of the systems is described
briefly in the following paragraphs.
Air inlet heating system
5 This system is fitted to certain carburettor
and all single-point fuel injection models, and
assists the vaporisation of the fuel, providing
more complete combustion of the fuel/air
mixture (see illustration). This is achieved by
controlling the temperature of the air entering
the engine.
6 The air drawn through the air inlet pipe from
the engine compartment is mixed with hot air
drawn from a shroud around the exhaust
manifold. The proportions of hot and cold air
are controlled by the position of a flap valve,
which in turn is controlled by a wax
thermostat and a vacuum capsule (connected
to the inlet manifold).
1.5 Typical air intake heating system
1 Air cleaner
2 Air ducting
3 Exhaust manifold
hot air duct
4 Flap valve
5 Wax thermostat
a Cold air
b Hot air