The exhaust system fitted in production is
made of aluminised steel, with stainless steel
used in the endplates and baffles of the rear
silencer. Individual sections of the system are
easily renewed in service.
Emission control for the UK market is
achieved largely by the inherent efficiency of
the fuel, ignition and engine management
systems. A welcome spin-off from such
efficiency is remarkably good fuel economy for
a vehicle of such size and weight.
Precautions
Fuel
Many of the procedures in this Chapter
require the removal of fuel lines and
connections which may result in some fuel
spillage. Residual pressure in fuel-injection
systems will remain in the fuel lines long after
the vehicle was last used, therefore extra care
must be taken when disconnecting a fuel line
hose. Loosen any fuel hose slowly to avoid a
sudden release of pressure which may cause
fuel spray. As an added precaution place a rag
over each union as it is disconnected to catch
any fuel which is forcibly expelled. Before
carrying out any operation on the fuel system
refer to the precautions given in “Safety first!”
at the beginning of this Manual and follow
them implicitly. Petrol is a highly dangerous
and volatile liquid and the precautions
necessary when handling it cannot be
overstressed
Tamperproof adjustment screws
Certain adjustment points in the fuel system
(and elsewhere) are protected by tamperproof
caps, plugs or seals. The purpose of such
tamperproofing is to discourage, and to deter,
adjustment by unqualified operators.
In some EU countries (though not yet in the
UK) it is an offence to drive a vehicle with
missing or broken tamperproof seals. Before
disturbing a tamperproof seal, satisfy yourself
that you will not be breaking local or national
anti-pollution regulations by doing so. Fit a
new seal when adjustment is complete when
this is required by law.
Do not break tamperproof seals on a vehicle
which is still under warranty.
Catalytic converter
The catalytic converter is a reliable and
simple device which needs no maintenance in
itself, but there are some facts of which an
owner should be aware if the converter is to
function properly for the full service life.
a)DO NOT use leaded petrol in a car
equipped with a catalytic converter the
lead will coat the precious metals,
reducing their converting efficiency and
will eventually destroy the converter.
b)Always keep the ignition and fuel systems
well-maintained in accordance with the
manufacturer’s schedule - particularly,
ensure that the air cleaner filter element,
the fuel filter and the spark plugs are
renewed at the correct interval - if the inletair/fuel mixture is allowed to become too
rich due to neglect, the unburned surplus
will enter and burn in the catalytic
converter, overheating the element and
eventually destroying the converter.
c)If the engine develops a misfire, do not
drive the car at all (or at least as little as
possible) until the fault is cured - the
misfire will allow unburned fuel to enter
the converter, which will result in
overheating, as noted above.
d)DO NOT push- or tow-start the car - this
will soak the catalytic converter in
unburned fuel, causing it to overheat when
the engine does start - see b) above.
e)DO NOT switch off the ignition at high
engine speeds - if the ignition is switched
off at anything above idle speed,
unburnedfuel will enter the (very hot)
catalytic converter, with the possible risk
of igniting on the element and damaging
the converter.
f)DO NOT use fuel or engine oil additives -
these may contain substances harmful to
the catalytic converter.
g)DO NOT continue to use the car if the
engine burns oil to the extent of leaving a
visible trail of blue smoke - the unburned
carbon deposits will clog the converter
passages and reduce the efficiency; in
severe cases the element will overheat.
h)Remember that the catalytic converter
operates at very high temperatures -
hence the heat shields on the car’s
underbody and the casing will become hot
enough to ignite combustible materials
which brush against it - DO NOT,
therefore, park the car in dry undergrowth,
over long grass or piles of dead leaves.
i)Remember that the catalytic converter is
FRAGILE, do not strike it with tools during
servicing work, take great care when
working on the exhaust system, ensure
that the converter is well clear of any jacks
or other lifting gear used to raise the car
and do not drive the car over rough
ground, road humps, etc, in such a way as
to “ground” the exhaust system.
j)In some cases, particularly when the car is
new and/or is used for stop/start driving, a
sulphurous smell (like that of rotten eggs)may be noticed from the exhaust. This is
common to many catalytic converter-
equipped cars and seems to be due to the
small amount of sulphur found in some
petrols reacting with hydrogen in the
exhaust to produce hydrogen sulphide
(H
2S) gas; while this gas is toxic, it is not
produced in sufficient amounts to be a
problem. Once the car has covered a few
thousand miles the problem should
disappear - in the meanwhile a change of
driving style or of the brand of petrol used
may effect a solution.
k)The catalytic converter, used on a well-
maintained and well-driven car, should
last for between 50 000 and 100 000 miles
- from this point on, careful checks should
be made at all specified service intervals
of the CO level to ensure that the
converter is still operating efficiently - if
the converter is no longer effective it must
be renewed.
See Chapter 1, Section 38.
1On carburettor models only, the air cleaner
can take in both hot and cold air. Hot air is
obtained from a shroud bolted to the exhaust
manifold.
2A flap valve in the air cleaner spout
determines the mix of hot and cold air. The
valve is operated by a vacuum diaphragm.
Vacuum is obtained from the inlet manifold
and is applied via a heat-sensing valve, which
cuts off the vacuum as the temperature of the
incoming air rises. Thus the air cleaner takes in
only hot air on starting from cold, changing
progressively to cold air as the engine warms
up (see illustrations).
3If the system fails, either the engine will take
a long time to warm up (flap stuck in “cold”
position), or it may run roughly and not
develop full power when warm (flap stuck in
“hot” position). Check it as follows.
3Air cleaner temperature control
- description and testing
2Air cleaner and element -
removal and refitting
4•4Fuel and exhaust systems
3.2b Air cleaner heat sensor3.2a Air cleaner vacuum diaphragm unit
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