2002 LAND ROVER DISCOVERY Oil cooler

ENGINE - TD5
12-1-12 DESCRIPTION AND OPERATION
Description
General
The Td5 diesel engine is a 2.5 litre, 5 cylinder, in-line direct injection unit having 2 valves per cylinder, operated by a
single overhead camshaft. The engine emissions, on pre EU3 models, comply with ECD2 (European Commission
Directive) and on EU3 models, comply with ECD3 legislative requirements. Both models employ electronic engine
management control, positive crankcase ventilation and exhaust gas recirculation to limit the emission of pollutants.
The unit is water cooled and turbo-charged and is controlled by an electronic engine management system.
The engine is a monobloc cast iron construction with an aluminium stiffening plate fitted to the bottom of the cylinder
block to improve lower structure rigidity. The cylinder head and sump are cast aluminium. An acoustic cover is fitted
over the upper engine to reduce engine generated noise.
The engine utilises the following features:
lElectronic Unit Injectors (EUI's) controlled by an Engine Management System for precise fuel delivery under
all prevailing operating conditions.
lTurbocharging which delivers compressed air to the combustion chambers via an intercooler for improved
power output.
lFuel Cooler
lOil Cooler
lCentrifuge Oil Filter
lHydraulic Lash Adjusters with independent finger followers
Cylinder block components
The cylinder block components are described below:
Cylinder Block
The cylinders and crankcase are contained in a single cast iron construction. The cylinders are direct bored and
plateau honed with lubrication oil supplied via lubrication jets for piston and gudgeon pin lubrication and cooling. It is
not possible to rebore the cylinder block if the cylinders become worn or damaged. Three metal core plugs are fitted
to the three centre cylinders on the right hand side of the cylinder block.
Lubrication oil is distributed throughout the block via the main oil gallery to critical moving parts through channels
bored in the block which divert oil to the main and big-end bearings via oil holes machined into the crankshaft. Oil is
also supplied from the cylinder block main gallery to the five lubrication jets which cool and lubricate the piston and
gudgeon pins. Plugs are used to seal both ends of the main oil gallery at front and rear of the engine block. An oil
cooler is fitted to the LH side of the engine block; ports in the oil cooler assembly mate with ports in the cylinder block
to facilitate coolant flow. Oil is diverted through the oil cooler, centrifuge filter and full-flow filter before supplying the
main oil gallery. A tapping in the oil filter housing provides a lubrication source for the turbocharger bearings and an
oil pressure switch is included in a tapping in the oil cooler housing which determines whether sufficient oil pressure
is available to provide engine lubrication and cooling.
Cylinder cooling is achieved by water circulating through chambers in the engine block casting. A threaded coolant
jacket plug is located at the front RH side of the cylinder block.
Cast mounting brackets are bolted to both sides of the engine block for mounting the engine to the chassis on the LH
and RH hydramount studs.
The gearbox bolts directly to the engine block; a gearbox shim plate is located between the adjoining faces of the
gearbox and the flywheel side of the engine block and is fixed to the rear of the engine block by two bolts. Two hollow
metal dowels locate the rear of the cylinder block to the gearbox shim plate. The gearbox casing provides the
mounting for the starter motor.
A port is included at the rear left hand side of the cylinder block which connects to the turbocharger oil drain pipe to
return lubrication oil to the sump.
A plug sealing the lubrication cross-drilling gallery is located at the front right hand side of the cylinder block and plugs
for the main lubrication gallery is included at the front and rear of the cylinder block.

ENGINE - TD5
DESCRIPTION AND OPERATION 12-1-15
Oil cooler
1Front oil gallery – full-flow filter to oil cooler
matrix
2Full-flow filter adaptor outlet port to oil cooler
(open at >74
° C)
3Full-flow filter inlet port
4Oil cooler housing
5Full-flow filter outlet port to cylinder block
6Coolant inlet port
7Oil cooler banjo bolt seals (2 off)
8Banjo bolts (2 off)
9Banjo bolt oil holes – to oil cooler matrix
10Rear oil gallery – full-flow filter/oil cooler outlet
to cylinder block11Centre oil gallery – from pump to full-flow filter
12Inlet port to centrifuge filter
13Sealing ring – centrifuge filter housing to oil
cooler housing
14Port – oil cooler matrix
15Oil cooler matrix
16Inlet port from pump via cylinder block to oil
cooler housing
17Outlet port from oil cooler housing to cylinder
block
18Rear view of oil cooler housing
The engine oil cooler assembly is located on the left hand side of the engine block behind the oil centrifuge and oil
filter. The housing is bolted to the engine block by seven bolts. A matrix is included in the oil cooler housing which
acts as a heat exchanger. Coolant flow circulates through the oil cooler housing under pressure from the coolant pump
and distributes the flow evenly around the matrix fins and then along the block into three core holes for cylinder
cooling. Coolant enters the oil cooler through a pipe with a rubber hose extension at the rear side of the engine. The
coolant hose is attached to the stub pipe of the oil cooler by a spring clip.
Oil drawn from the sump by the oil pump passes through the oil cooler via the cylinder block. The flow of coolant
around the exterior surface of the oil cooler matrix cools a proportion of the engine oil flow as it passes through the
oil cooler matrix.
The oil cooler is sealed to the cylinder block by a gasket which must be replaced every time the oil cooler housing is
removed.

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
12-1-18 DESCRIPTION AND OPERATION
Oil filter housing thermostat
1Circlip
2Thermostat end cap
3Oil seal
4Thermostatic valve
5Return spring
6Oil filter housing
7Threaded insert
The oil filter housing contains a thermostatically controlled valve to control the direction and proportion of oil flow
through the oil cooler matrix. When the oil temperature is cool, the centre spindle of the thermostatic element is
compressed. In this condition the valve completely seals the passage to the turbocharger feed tapping and flow is
directed through the oil filter adaptor housing, passing from the outlet of the full-flow filter to the cylinder block via the
rear oil return gallery in the oil cooler housing. A proportion of the oil flow from the right hand filter outlet port is passed
through to the oil cooler matrix to supply the turbocharger oil feed line.
When the oil temperature rises, the heated wax in the thermostat causes the thermostat centre spindle to rise and
push against the housing end cap, compressing the valve spring further and so opening the valve. In this condition
oil flow from the outlet side of the full-flow filter is allowed to pass directly to the turbocharger oil feed line and reverses
the flow through the oil cooler matrix, which now delivers a proportion of cooled oil flow to the cylinder block via the
outlet port at the right hand side of the oil cooler housing.
The following table indicates approximate values for thermostat plunger travel against temperature:
The filter canister contains a by-pass valve which opens when the engine is cold or if the filter becomes blocked. The
by-pass valve opens when a pressure drop of greater than 1.6 kg/cm
2 (157 kPa, 23 psi) is experienced.
Thermostat plunger travel mm (in.) Oil temperature °C
0 (0) < 74 °C
5 (0.20) 80 °C
12 (0.47) 90 °C
16 (0.63) 130 °C

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
DESCRIPTION AND OPERATION 12-1-23
Fuel connector block
A = Pre EU3 models, B = EU3 models
1Fuel connector block assembly
2Outlet stub pipe
3Stub pipe – to fuel cooler
4Fuel temperature sensor
5Fuel pressure regulator
6Spill fuel return connection (EU3 models only)
A cast and machined alloy fuel connector block assembly is located at the rear RH side of the cylinder head, attached
by three flanged bolts. A metal gasket is used to seal the faces between the fuel connector block and the cylinder
head, which must be replaced every time the fuel connector block is removed.
CAUTION: The cylinder head incorporates drillings for the fuel injection system, any contamination which
enters these drillings could cause engine running problems or injector failure. It is therefore, essential that
absolute cleanliness is maintained when carrying out work on the cylinder head.
CAUTION: The valve heads, tips of the injectors and glow plugs protrude below the face of the cylinder head
and will be damaged if the cylinder head is stored face down.
Camshaft carrier
The cast aluminium alloy camshaft carrier is bolted to the cylinder head by thirteen screws. The camshaft carrier and
cylinder head assembly is attached to the cylinder block by twelve cylinder head retaining bolts which pass through
the camshaft carrier and the cylinder head to secure the assembly to the cylinder block.
The carrier is machined together with the cylinder head to form a matched pair for carrying the camshaft.
Non-return valve
A non-return valve is located at the front, bottom LH side of the cylinder head. The non-return valve prevents oil from
draining from the lash adjusters and is an integral component within the cylinder head and is non-serviceable.

ENGINE - TD5
DESCRIPTION AND OPERATION 12-1-29
Lubrication circuit
Cylinder block flow
1Oil squirt jets (5 off)
2Main oil delivery gallery
3Inflow from oil cooler housing
4Flow to oil cooler / filters (from oil pump via
cylinder block)
5Sump
6Oil pick-up pipe
7Flow from oil pump (relief-valve in housing)
8Oil pump9Cross-drilling supply to main and crankshaft
bearings
10To cylinder head

ENGINE - TD5
12-1-30 DESCRIPTION AND OPERATION
Oil from the sump is drawn up through a two-piece plastic pick-up which contains a mesh to siphon any relatively large
pieces of material which could cause damage to the pump. The head of the pick-up is centrally immersed in the sump
oil and oil is delivered to the inlet side of the eccentric rotor pump through a gallery in the stiffener plate.
Pressurised oil from the pump is passed through to the cylinder block where it is delivered to the centrifuge filter and
full-flow filter via a port in the RH cylinder block which interfaces with a port in the centre gallery of the oil cooler
housing. The oil pump contains an oil pressure relief valve which opens to allow oil to be recirculated back around the
pump if the oil pressure increases to a high enough level.
10% of the oil flow from the pump is diverted through the centrifuge filter and returned to the sump via the centrifuge
filter drain tube. The remaining 90% of the oil passes through the standard full-flow filter to the main oil gallery in the
cylinder block.