gas type LAND ROVER DISCOVERY 2002 Workshop Manual

CONTENTS
CONTENTS 5
Description ...................................................................................................................................... 12-2-6
ADJUSTMENTS
Engine oil pressure check .............................................................................................................. 12-2-11
REPAIRS
Seal - crankshaft - rear .................................................................................................................. 12-2-13
Gasket - cylinder head - LH ........................................................................................................... 12-2-14
Gasket - cylinder head - RH ............................................................................................................ 12-2-16
Gasket - rocker cover - LH ............................................................................................................ 12-2-19
Gasket - rocker cover - RH ............................................................................................................ 12-2-20
Mounting - front - LH ...................................................................................................................... 12-2-22
Mounting - front - RH ..................................................................................................................... 12-2-23
Mounting - rear - LH ....................................................................................................................... 12-2-24
Mounting - rear - RH ...................................................................................................................... 12-2-25
Engine assembly............................................................................................................................. 12-2-26
Flywheel ........................................................................................................................................ 12-2-31
Plate - drive - automatic ................................................................................................................ 12-2-32
Ring gear - starter ......................................................................................................................... 12-2-33
Filter - oil ....................................................................................................................................... 12-2-34
Strainer - oil pick-up ...................................................................................................................... 12-2-35
Pump - oil ...................................................................................................................................... 12-2-35
Gasket - sump ................................................................................................................................ 12-2-36
Switch - oil pressure ....................................................................................................................... 12-2-38
Cooler - engine oil .......................................................................................................................... 12-2-39
Gasket - timing gear cover ............................................................................................................ 12-2-40
Seal - cover - timing gears ............................................................................................................ 12-2-42
OVERHAUL
Gasket - inlet manifold ................................................................................................................... 12-2-45
Gasket - exhaust manifold ............................................................................................................. 12-2-48
Seal - crankshaft - rear - automatic models .................................................................................... 12-2-49
Seal - crankshaft - rear - manual models ........................................................................................ 12-2-50
Bearing - spigot - crankshaft .......................................................................................................... 12-2-52
Gasket - engine sump .................................................................................................................... 12-2-53
Strainer - oil pick-up ....................................................................................................................... 12-2-54
Seal - timing gear cover ................................................................................................................. 12-2-54
Gasket - timing gear cover ............................................................................................................. 12-2-55
Timing chain and gears .................................................................................................................. 12-2-57
Rocker shaft - overhaul ................................................................................................................. 12-2-59
Gasket - cylinder head .................................................................................................................... 12-2-60
Cylinder head - overhaul ................................................................................................................ 12-2-62
Piston assemblies ........................................................................................................................... 12-2-67
Bearings - connecting rods ............................................................................................................ 12-2-71
Crankshaft and main bearings ........................................................................................................ 12-2-72
Camshaft ....................................................................................................................................... 12-2-76
EMISSION CONTROL - Td5..................................................................... 17-1-1
DESCRIPTION AND OPERATION
EGR system components - type 1 .................................................................................................. 17-1-1
EGR system components - type 2 .................................................................................................. 17-1-2
Emission Control Systems .............................................................................................................. 17-1-4
Crankcase emission control ............................................................................................................ 17-1-4
Exhaust gas recirculation ................................................................................................................ 17-1-5

GENERAL INFORMATION
03-3
Environmental Precautions
General
This section provides general information which can
help to reduce the environmental impacts from the
activities carried out in workshops.
Emissions to air
Many of the activities that are carried out in
workshops emit gases and fumes which contribute to
global warming, depletion of the ozone layer and/or
the formation of photochemical smog at ground
level. By considering how the workshop activities are
carried out, these gases and fumes can be
minimised, thus reducing the impact on the
environment.
Exhaust fumes
Running car engines is an essential part of workshop
activities and exhaust fumes need to be ventilated to
atmosphere. However, the amount of time engines
are running and the position of the vehicle should be
carefully considered at all times, to reduce the
release of poisonous gases and minimise the
inconvenience to people living nearby.
Solvents
Some of the cleaning agents used are solvent based
and will evaporate to atmosphere if used carelessly,
or if cans are left unsealed. All solvent containers
should be firmly closed when not needed and
solvent should be used sparingly. Suitable
alternative materials may be available to replace
some of the commonly used solvents. Similarly,
many paints are solvent based and the spray should
be minimised to reduce solvent emissions.
Refrigerant
It is illegal to release any refrigerants into the
atmosphere. Discharge and replacement of these
materials from air conditioning units should only be
carried out using the correct equipment.
Checklist
Always adhere to the following.
Engines:
ldon't leave engines running unnecessarily;
lminimise testing times and check where the
exhaust fumes are being blown.
Materials:
lkeep lids on containers of solvents;
lonly use the minimum quantity;
lconsider alternative materials;
lminimise over-spray when painting. Gases:
luse the correct equipment for collecting
refrigerants;
ldon't burn rubbish on site.
Discharges to water
Most sites will have two systems for discharging
water: storm drains and foul drains. Storm drains
should only receive clean water, foul drains will take
dirty water.
The foul drain will accept many of the normal waste
waters such as washing water, detergents and
domestic type wastes, but oil, petrol, solvent, acids,
hydraulic oil, antifreeze and other such substances
should never be poured down the drain. If in any
doubt speak to the Water Company first.
Every precaution must be taken to prevent spillage of
oil, fuel, solvents etc. reaching the drains. All
handling of such materials must take place well away
from the drains and preferably in an area with a kerb
or wall around it, to prevent discharge into the drain.
If a spillage occurs it should be soaked up
immediately. Having a spill kit available will make
this easier.
Additional precautions
Check whether the surface water drains are
connected to an oil water separator, this could
reduce the pollution if an incident was to occur. Oil
water separators do need regular maintenance to
ensure effectiveness.
Checklist
Always adhere to the following.
Disposal:
lnever pour anything down a drain without first
checking that it is environmentally safe to do so,
and that it does not contravene any local
regulations or bye-laws;
l have oil traps emptied regularly.
Spillage prevention:
lstore liquids in a walled area;
lmake sure that taps on liquid containers are
secure and cannot be accidentally turned on;
lprotect bulk storage tanks from vandalism by
locking the valves;
ltransfer liquids from one container to another in
an area away from open drains;
lensure lids are replaced securely on containers;
lhave spill kits available near to points of storage
and handling of liquids.

GENERAL INFORMATION
03-25
lComponents must not remain uncapped for
longer than 15 minutes. In the event of a delay,
the caps must be fitted.
lWhen disconnecting, immediately cap all air
conditioning pipes to prevent ingress of dirt and
moisture into the system.
lThe receiver/drier contains desiccant which
absorbs moisture. It must be positively sealed at
all times. A receiver/drier that has been left
uncapped must not be used, fit a new unit.
lThe receiver/drier should be the last component
connected to the system to ensure optimum
dehydration and maximum moisture protection
of the system.
lWhenever the refrigerant system is opened, the
receiver/drier must be renewed immediately
before evacuating and recharging the system.
lUse alcohol and a clean lint-free cloth to clean
dirty connections.
lEnsure that all new parts fitted are marked for
use with R134a.
When a major repair has been completed, a leak test
should be conducted; refer to the Air Conditioning
section of this manual for the correct procedure.
Refrigerant oil
Refrigerant oil easily absorbs water and must not
be stored for long periods. Do not pour unused
refrigerant oil back into the container. Always
use an approved refrigerant oil.

+ CAPACITIES, FLUIDS AND
LUBRICANTS, Lubrication.
When replacing components in the A/C system,
drain the refrigerant oil from the component being
replaced into a graduated container. On assembly,
add the quantity of refrigerant oil drained to the new
component.
Compressor
A new compressor is sealed and pressurised with
Nitrogen gas. When fitting a new compressor, slowly
release the sealing cap; gas pressure should be
heard to vent as the seal is broken.
CAUTION: A new compressor should always be
sealed and could be pressurised with nitrogen
gas. To avoid possible oil loss, release the
sealing cap(s) slowly. Do not remove the cap(s)
until immediately prior to connecting the air
conditioning pipes to the compressor.Rapid refrigerant discharge
If the air conditioning system is involved in accident
damage and the system is punctured, the refrigerant
will discharge rapidly. The rapid discharge of
refrigerant will also result in the loss of most of the oil
from the system. The compressor must be removed
and all the remaining oil in the compressor drained
and refilled as instructed in the air conditioning
section of this manual.
Precautions for refrigerant recovery, recycling
and recharging
When the air conditioning system is recharged, any
existing refrigerant is first recovered from the system
and recycled. The system is then charged with the
required weight of refrigerant and volume of
refrigerant oil.
WARNING: Refrigerant must always be recycled
before re-use to ensure that the purity of the
refrigerant is high enough for safe use in the air
conditioning system.
Recycling should always be carried out with
equipment which is design certified by
Underwriter Laboratory Inc. for compliance with
SAE J1991. Other equipment may not recycle
refrigerant to the required level of purity.
A R134a Refrigerant Recovery Recycling
Recharging Station must not be used with any
other type of refrigerant.
Refrigerant R134a from domestic and
commercial sources must not be used in motor
vehicle air conditioning systems.
CAUTION: The system must be evacuated
immediately before recharging commences.
Delay between evacuation and recharging is not
permitted.

ENGINE - TD5
12-1-16 DESCRIPTION AND OPERATION
Oil filters
The Td5 engine features two types of oil filter; the main filter is a standard disposable cartridge-type full-flow oil filter
which is augmented with a by-pass centrifuge filter used to filter out particulate matter having a diameter smaller than
15 micron but greater than 3 micron.
1Centre spindle
2Spindle oil holes (2 off)
3Centrifuge filter housing
4Centrifuge filter drain pipe
5Port – centrifuge filter drain pipe to sump6Filter rotor
7Internal seal
8Cover
9Cover bolts (2 off)
The centrifuge filter is located on the left hand side of the engine block by the exhaust manifold and is housed in a pot
which is bolted to the oil cooler housing by means of three bolts. The pot contains a rotor located on a central spindle
which spins at up to 15,000 revs/min. when oil is flowing through the unit under pressure. The rotor contains two fine
holes drilled at obtuse angles which cause the rotor to spin about the centre spindle when high pressure oil is passing
through it. The inner surface of the rotor captures carbon deposits and small particulate matter as it is thrown outwards
under centrifugal force to form a sludge on the inner walls of the rotor. The unit is able to trap very fine impurities that
build up in the oil that would be too small to filter using the normal paper-element type full-flow filters alone.
Approximately 10% of the total oil flow enters the centrifuge pot through a side port in the pot casting which is mated
to an outlet port at the lower side of the oil cooler housing. A rubber O-ring sits in a recess around the oil cooler port
which seals the faces between the centrifuge pot and oil cooler port, and it must be replaced every time the centrifuge
assembly is removed. Oil leaves the centrifuge pot through a drain tube which is attached to the base of the pot by
means of two fixing screws. The lower end of the drain tube returns oil to the sump and is fixed to the sump by means
of two screws. Gaskets are included at the port interfaces between the oil drain tube and the centrifuge pot, and the
oil drain tube and sump return port; these gaskets must be replaced every time the oil drain tube is removed.
The centrifuge cover is fixed to the pot by two screws and is sealed by an 'O'-ring.

ENGINE - TD5
DESCRIPTION AND OPERATION 12-1-19
Oil Pressure switch
The oil pressure switch is located in a port on the outlet side of the oil cooler housing. It detects when a safe operating
pressure has been reached during engine starting and initiates the illumination of a warning light in the instrument
pack if the pressure drops below a given value.
Crankshaft, sump and oil pump components
The crankshaft, sump and oil pump components are described below:
Sump
The sump is a wet-type, of aluminium construction and is sealed to the engine block by means of a rubber gasket and
twenty fixing bolts. The four bolts at the gearbox end of the sump are longer than the other sixteen bolts.
The sump gasket incorporates compression limiters (integrated metal sleeves) at the bolt holes, which are included
to prevent distortion of the gasket when the sump to cylinder block bolts are being tightened.
The oil drain plug is fitted at the bottom of the oil sump reservoir. An oil return drain pipe is also attached to the oil
sump which returns oil from the centrifugal filter.
Stiffener Plate
The stiffener plate assembly provides lower engine block rigidity and utilises dowels to align it to the bottom of the
cylinder block. A rotary oil pump is integral with the stiffener plate and an oil pick-up and strainer assembly is fitted
to the underside of the stiffener plate. The stiffener and oil pump assembly is secured to the cylinder block by 22 bolts.

ENGINE - TD5
12-1-26 DESCRIPTION AND OPERATION
Camshaft cover and engine cover components
The camshaft cover and engine cover components are described below:
Camshaft cover
The camshaft cover is cast from aluminium alloy and is fixed to the camshaft carrier/cylinder head assembly by 13
bolts. The cover has spacers and sealing washers inserted into each of the thirteen bolt holes.
A breather hose is connected to a port at the top of the camshaft cover by means of a hose clip which vents crankcase
gases back to the air intake via a breather valve in the air intake tract, located forward of the turbocharger in the
flexible air intake duct.
A rubber seal is fitted between the camshaft cover.
An oil filler aperture is included in the top of the camshaft cover, which is sealed with a plastic cap with integral rubber
seal.
Camshaft timing chain components
The timing chain cover and timing chain components are described below:
Timing chain cover
The timing chain cover is cast and machined aluminium alloy and is attached to the cylinder head by a bolt at the RH
top of the cover and by a stud and nut at the LH top of the cover. Eight screws are used to attach the timing chain
cover to the front of the engine block. The timing cover is located to the cylinder block front face by two dowels.
A viscous fan is attached to an idler pulley at the front of the engine block. The fan bearing is located on a shaft and
held in place by a circlip and a bearing flange, the inner race of the fan bearing is an interference fit on the shaft. The
fan idler pulley is attached to the bearing hub by three bolts, and the fan itself is secured to the pulley and bearing
shaft by a left hand threaded nut.

+ COOLING SYSTEM - Td5, DESCRIPTION AND OPERATION, Description.
The front of the crankshaft passes through a hole in the lower part of the timing cover. An oil seal is pressed into a
recess in the front of the timing cover to seal the interface between the front of the crankshaft and the timing cover.
A stub pipe is fitted to the front RH side of the timing cover which is used to attach the oil drain pipe from the vacuum
pump by means of a hose and spring clip.
Timing chains
The timing chain between the camshaft and crankshaft sprockets is a duplex type, each chain having 56 links. The
timing chain is contained between a fixed plastic guide and an hydraulically adjustable plastic tensioner arm which
are attached to the front of the engine block.
To cope with higher injection loads of the EU3 engine, the timing drive between the camshaft and crankshaft has been
upgraded. This requires thicker chain links to be used, therefore, the individual pre EU3 and EU3 components are not
interchangeable.
To distinguish between the two timing chains the links are different colours. A pre EU3 chain has blue links and a EU3
chain has bronze links.
The oil pump timing chain is a single type and traverses the oil pump sprocket and the rear crankshaft sprocket.
The timing chains are oil lubricated, with oil being provided by a chain lubrication jet and from oil flow returning back
to the sump from the cylinder head. An oil hole is included at the front left hand side of the cylinder head which supplies
oil from the cylinder head oil galleries.

ENGINE - TD5
REPAIRS 12-1-45
Refit
1.Clean rocker shaft and mating faces.
CAUTION: If rockers or rocker shaft are to
be replaced, ensure replacements are
correct. Engine Serial No. Prefixes 10P to
14P are fitted with type A rocker arms and
shaft. Engine Serial No. Prefixes 15P to 19P
are fitted with type B rocker arms and shaft.
Type B rocker arms and shaft may be fitted
to Engine Serial No. Prefixes 10P to 14P as
an assembly.
2.Fit new rocker adjusting screws fully into rocker
arm. Fit new lock nuts to screws but do not
tighten.
CAUTION: Ensure screws are correct for
type of rocker arms fitted. Replacement
screws for Engine Serial No. Prefixes 15P to
19P have a centre punch mark adjacent to
the adjusting slot. These screws are not
interchangeable with those fitted to Engine
Serial No. Prefixes 10P to 14P.
3.Fit rocker shaft ensuring it is located on dowel.
4.Fit and progressively tighten new rocker shaft
bolts to 33 Nm (24 lbf.ft). 5.Before refitting the camshaft cover the
electronic injection unit (EUI) rockers must be
adjusted.
6.Remove tool LRT-12-058 from camshaft.
7.Rotate engine clockwise until No 1 injector lobe
is at full lift.
8.Rotate rocker adjusting screw clockwise until
the injector plunger is felt to bottom out.
9.Rotate rocker adjusting screw anti-clockwise
one complete turn to give plunger the required
bump clearance and tighten rocker arm
adjusting screw locknut to 16 Nm (12 lbf.ft) .
CAUTION: Ensure screw does not turn as
locknut is tightened.
10.Carry out above procedure for the remaining 4
rocker arms.
11.After completion of rocker arm adjustment,
slowly rotate engine clockwise 2 complete
turns by hand to ensure that no injectors are
bottoming out on their plungers.
12.Fit camshaft cover gasket.

+ ENGINE - Td5, REPAIRS, Gasket -
cover - camshaft.
13.Fit cooling fan coupling.

+ COOLING SYSTEM - Td5, REPAIRS,
Fan - viscous.

ENGINE - V8
12-2-6 DESCRIPTION AND OPERATION
Description
General
The V8 petrol engine is an eight cylinder, water cooled unit having two banks of four cylinders positioned at 90 degrees
to each other. The engine comprises five main castings - two cylinder heads, cylinder block, timing cover and the oil
sump, all of which are manufactured from aluminium alloy.
NAS market vehicles from 03 model year receive a 4.6 litre version of the V8 engine to replace the previous 4.0 litre
version.
Cylinder heads
The cylinder heads are fitted with replaceable valve guides and valve seat inserts with the combustion chambers
formed in the head. Each cylinder head is sealed to the cylinder block with a gasket. The exhaust manifolds are bolted
to the outside of each cylinder head whilst the inlet manifolds are located in the centre of the 'Vee' and are bolted to
the inside face of each head. Inlet and exhaust manifolds are sealed to the cylinder heads by means of gaskets.
Each cylinder has a single inlet and exhaust valve. The exhaust valves are of the 'carbon break' type, a recess on the
valve stem prevents a build-up of carbon in the valve guide by dislodging particles of carbon as the valve stem moves
up and down the guide. Inlet and exhaust valve stem oil seals are fitted at the top of each valve guide. Valve operation
is by means of rocker arms, push rods and hydraulic tappets. Each of the rocker arms is located on a rocker shaft
which is supported by means of pedestals bolted to the cylinder heads. A spring, positioned on either side of each
rocker arm, maintains the correct relative position of the arm to its valve stem. The rocker arms are operated directly
by the push rods which pass through drillings in the cylinder heads and cylinder block. The bottom end of each push
rod locates in a hydraulic tappet operated by the single, chain driven camshaft.
The rocker covers are bolted to the cylinder heads and are sealed to the heads by a rubber gasket. Stub pipes for
crankcase ventilation hose connections are fitted to each rocker cover, the pipe in the right hand cover incorporates
an oil separator. The engine oil filler cap is situated in the right hand cover.
Cylinder block and camshaft
The cylinder block is fitted with cast iron cylinder liners which are shrink fitted and locate on stops in the block. The
camshaft is positioned in the centre of the cylinder block and runs in one piece bearing shells which are line bored
after fitting. Camshaft end-float is controlled by a thrust plate bolted to the front of the cylinder block. A timing gear,
chain driven by the crankshaft timing gear is bolted to the front of the camshaft.
Crankshaft and main bearings
The crankshaft is carried in five main bearings. The upper main bearing shell locations are an integral part of the
cylinder block casting. The lower main bearing caps are bolted to the cylinder block on either side of the upper bearing
shell locations with an additional bolt being inserted into each cap from either side of the cylinder block. The rear
main bearing cap carries the crankshaft rear oil seal and is sealed to the cylinder block by means of cruciform shaped
seals in each side of the cap. Number four main bearing cap carries the stud fixing for the oil pick-up pipe. Lower
main bearing shells are plain whilst the upper shells have an oil feed hole and are grooved. Crankshaft end-float is
controlled by the thrust faces of the upper centre shell. The crankshaft timing gear is located on the front of the
crankshaft by means of a Woodruff key which is also used to drive the gear type oil pump. The flywheel/drive plate
carries the crankshaft position sensor reluctor ring and is dowel located and bolted to the flywheel.
Timing cover
The timing cover is bolted to the front of the cylinder block and is sealed to the block with a gasket. The disposable,
full flow oil filter canister is screwed on to the timing cover which also carries the oil pressure switch, oil pressure relief
valve and crankshaft front oil seal. The gear type oil pump is integral with the cover which also has an internal oilway
to direct oil from the oil cooler to the filter.
NOTE: Oil coolers are only fitted to vehicles up to VIN 756821.

EMISSION CONTROL - TD5
17-1-4 DESCRIPTION AND OPERATION
Emission Control Systems
Engine design has evolved in order to minimise the emission of harmful by-products. Emission control systems fitted
to Land Rover vehicles are designed to maintain the emission levels within the legal limits pertaining for the specified
market.
Despite the utilisation of specialised emission control equipment, it is still necessary to ensure that the engine is
correctly maintained and is in good mechanical order, so that it operates at its optimum condition.
In addition to emissions improvements through engine design and the application of electronic engine management
systems, special emission control systems are used to limit the pollutant levels developed under certain conditions.
Two main types of additional emission control system are utilised with the Td5 engine to reduce the levels of harmful
emissions released into the atmosphere. These are as follows:
1Crankcase emission control – also known as blow-by gas emissions from the engine crankcase.
2Exhaust gas recirculation – to reduce NO
2 emissions.
Crankcase emission control
All internal combustion engines generate oil vapour and smoke in the crankcase as a result of high crankcase
temperatures and piston ring and valve stem blow-by, a closed crankcase ventilation system is used to vent
crankcase gases back to the air induction system and so reduce the emission of hydrocarbons.
Gases from the crankcase are drawn into the inlet manifold to be burnt in the combustion chambers with the fresh air/
fuel mixture. The system provides effective emission control under all engine operating conditions.
Crankcase gases are drawn through the breather port in the top of the camshaft cover and routed through the breather
hose and breather valve on the flexible air intake duct to be drawn into the turbocharger intake for delivery to the air
inlet manifold via an intercooler.
An oil separator plate is included in the camshaft cover which removes the heavy particles of oil before the crankcase
gas leaves via the camshaft cover port. The rocker cover features circular chambers which promote swirl in the oil
mist emanating from the cylinder head and camshaft carrier. As the mist passes through the series of chambers
between the rocker cover and oil separator plate, oil particles are thrown against the separator walls where they
condense and fall back into the cylinder head via two air inlet holes located at each end of the rocker cover.
The breather valve is a depression limiting valve which progressively closes as engine speed increases, thereby
limiting the depression in the crankcase. The valve is of moulded plastic construction and has a port on the underside
which plugs into a port in the flexible air intake duct. A port on the side of the breather valve connects to the camshaft
cover port by means of a breather hose which is constructed from a heavy-duty braided rubber hose which is held in
place by hose clips. A corrugated plastic sleeve is used to give further protection to the breather hose. The breather
valve is orientation sensitive, and “TOP” is marked on the upper surface to ensure it is mounted correctly.
It is important that the system is airtight so hose connections to ports should be checked and the condition of the
breather hose should be periodically inspected to ensure it is in good condition.

EMISSION CONTROL - TD5
17-1-10 DESCRIPTION AND OPERATION
EGR systems
There are two types of exhaust gas recirculation system used with the Td5 engine dependent on legislation and
market requirements, these are type 1 and type 2.
Type 1 EGR system is fitted to all Td5's built up to the introduction of 2002 MY, except for Japanese specification
vehicles.
Type 2 EGR system is fitted to all Japanese specification vehicles and was introduced into European markets for 2002
MY to meet EU3 emission requirements. An additional feature introduced at 2002 MY is the EGR cooler, which is
bolted to the front of the cylinder head.
EGR system - type 1
This EGR system features a single modulator which is electrically controlled to modulate a vacuum source to the EGR
valve. The controlled vacuum opens and closes the valve by the amount required to ensure the optimal proportion of
exhaust gas is allowed through to the inlet manifold to be combined with the fresh air intake. Control feedback is
achieved by monitoring the mass of fresh air flowing through the mass air flow sensor.
The modulator operation is controlled by a signal from the ECM which determines the required amount of EGR
needed in response to inputs relating to air flow and engine operating and ambient conditions. The ECM is low-side
driven, sinking current returned from the vacuum modulator for switching operating condition.
The exhaust gases are routed from the exhaust manifold through a shaped metal pipe which connects to the
underside of the EGR valve. The pipe is held securely in position to the front of the cylinder head using a clamp
bracket. The EGR pipe is attached to a mating port at the front end of the exhaust manifold using two Allen screws
and at the EGR valve assembly by a metal band clamp. The two Allen screws fixing the EGR pipe to the exhaust
manifold should be replaced every time the EGR pipe is removed. Extreme care should be exercised when
removing and refitting the EGR pipe to avoid damage.
When a vacuum is applied to the EGR suction port, it causes a spindle with sealing disc (EGR valve) to be raised,
thus opening the port at the EGR pipe to allow the recirculated exhaust gas to pass through into the inlet manifold.
The valve is spring loaded so that when the vacuum is removed from the suction port the valve returns to its rest
position to tightly close the exhaust gas port.
By controlling the quantity of recirculated exhaust gas available in the inlet manifold, the optimum mix for the prevailing
engine operating conditions can be maintained, which ensures the intake gas to the combustion chambers will have
burning rate properties which will reduce the NO
x emissions to an acceptable level. Normally, full recirculation is only
applicable when the NO
x emissions are most prevalent.
EGR system - type 2
This system features twin modulators mounted one above the other on a metal plate located on the inner wing at the
RH side of the engine. The modulators are electrically controlled by the engine management system and are used to
modulate a vacuum source to the EGR valve and a supplementary Inlet Throttle (ILT) valve; the two valves are
controlled to operate in tandem. The ILT valve vacuum pot is mounted adjacent to the EGR valve housing and has a
linkage which connects to a butterfly valve mounted in front of the EGR valve at the air intake manifold.
The modulator operations are electrically controlled by signals from the engine management system which
determines the required volume of exhaust gas needed in response to inputs relating to air flow, engine operating
conditions and ambient parameters such as temperature and altitude. The engine management ECM switches on the
circuit by completing the path to ground, operating the vacuum modulators.
Pre EU3 models: The exhaust gases are routed from the exhaust manifold through a shaped metal pipe which
connects to the underside of the EGR valve. The pipe is held securely in position to the front of the engine cylinder
head using a metal clamp bracket. The EGR pipe is attached to a mating port at the front end of the exhaust manifold
using two Allen screws and at the EGR valve assembly by a metal band clamp. The two Allen screws fixing the EGR
pipe to the exhaust manifold should be replaced every time the EGR pipe is removed. Extreme care should be
exercised when removing and refitting the EGR pipe to avoid damage.