15 Inlet manifold-
removal and refitting
4
Note: Refer to the warning note in Section 1
before proceeding.
Removal
1 The inlet manifold is a two-piece assembly
comprising an upper and lower section bolted
together (see illustration) .
2 Drain the cooling system with reference to
Chapter 1.
3 Depressurise the fuel system as described
in Section 2.
4 Disconnect the battery negative (earth) lead
(refer to Chapter 5A, Section 1).
5 Remove the air inlet components (Section
4) and disconnect the accelerator cable from
the throttle linkage (Section 5).
6 Remove the fuel injectors and fuel rail as
described in Section 14.
7 Noting their locations, disconnect the
coolant, vacuum and breather hoses from the
manifold.
8 Disconnect the wiring multi-plugs from the
engine sensors at the inlet manifold.
9 Undo the retaining bolts, and withdraw the
manifold from the cylinder head. Note the
location of the engine lifting bracket and earth
lead, where fitted. Remove the gasket.
10 With the manifold removed, clean all
traces of the old gasket from the mating surfaces of the manifold and the cylinder
head.
Refitting
11
Refitting is the reversal of removal. Use a
new gasket, and tighten the retaining bolts to
the specified torque (see illustration).
Refit the remainder of the components with
reference to the appropriate Chapters of this
manual. Refill the cooling system as
described in Chapter 1 on completion.
16 Turbocharger - general
information and precautions
General information
1 A water-cooled turbocharger is used on all
Turbo models covered by this manual. The
turbocharger increases the efficiency of the
engine by raising the pressure in the inlet
manifold above atmospheric pressure.
Instead of the air/fuel mixture being simply
sucked into the cylinders it is actively forced
in.
2 Energy for the operation of the
turbocharger comes from the exhaust gas.
The gas flows through a specially-shaped
housing (the turbine housing) and in so doing
spins the turbine wheel. The turbine wheel is
attached to a shaft, at the other end of which
is another vaned wheel known as the compressor wheel. The compressor wheel
spins in its own housing and compresses the
inducted air on the way to the inlet manifold.
3
After leaving the turbocharger, the
compressed air passes through an
intercooler, which is an air-to-air heat
exchanger mounted with the radiator. Here
the air gives up heat which it acquired when
being compressed. This temperature
reduction improves engine efficiency and
reduces the risk of detonation.
4 Boost pressure (the pressure in the inlet
manifold) is limited by the turbocharger
wastegate control, which diverts the exhaust
gas away from the turbine wheel in response
to the boost control valve. The valve is
controlled by the EEC IV engine management
module.
5 The turbo shaft is pressure-lubricated by
means of a feed pipe from the engine’s main oil
gallery. The shaft “floats” on a cushion of oil. A
drain pipe returns the oil to the sump.
6 Water cooling reduces the operating
temperature of the turbocharger, and in
particular, the shaft bearings. Water continues
to circulate by convection after the engine has
stopped, so cooling the unit if it is hot after a
long run.
Precautions
7 The turbocharger operates at extremely
high speeds and temperatures. Certain
precautions must be observed to avoid
premature failure of the turbo or injury to the
operator. a) Do not operate the turbo with any parts
exposed. Foreign objects falling onto the
rotating vanes could cause extensive
damage and (if ejected) personal injury.
b) Do not race the engine immediately after
start-up, especially if it is cold. Give the oil
a few seconds to circulate.
c) Always allow the engine to return to idle
speed before switching it off - do not blip
the throttle and switch off, as this will
leave the turbo spinning without
lubrication.
d) Allow the engine to idle for several
minutes before switching off after a high-
speed run.
e) Observe the recommended intervals for oil and filter changing, and use a
reputable oil of the specified quality.
Neglect of oil changing, or use of inferior
oil, can cause carbon formation on the
turbo shaft and subsequent failure.
17 Intercooler -
removal and refitting
2
Removal
1 Disconnect the battery negative (earth) lead
(refer to Chapter 5A, Section 1).
2 Remove the flexible hose connecting the
intercooler to the air inlet duct, then the pipe
4C•8 Fuel system - electronic fuel injection engines
15.1 Exploded view of the inlet manifold arrangement
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