2002 LAND ROVER DISCOVERY low oil pressure

ENGINE - TD5
12-1-24 DESCRIPTION AND OPERATION
Camshaft
The camshaft is machined from cast steel and is located between the cylinder head and the camshaft carrier, and the
six bearing journals are line bored between the two components to form a matched pair. The machined camshaft has
15 lobes. Ten lobes operate the inlet and exhaust valves through hydraulic lash adjusters and finger followers which
are located below the camshaft. Five larger lobes activate the injector rockers which are located above the camshaft
on the rocker shaft and are used to generate fuel pressure in the EUI injectors.
The camshaft is sprocket driven via a duplex chain connected to the crankshaft sprocket at a speed ratio of 2:1. The
camshaft sprocket is fixed to the front end of the camshaft by three bolts.
Camshaft lubrication is splash and channel fed via pressurised oil flowing through galleries in the cylinder head.
Rocker shaft and Rocker Arms
A = Pre EU3 rocker arm, B = EU3 rocker arm
1Rocker shaft
2Rocker arm adjusting screw
3Rocker arm
4EUI pin and roller assembly
5Roller pin retention slug6Camshaft lobe
7Injector spring
8Injector push-rod
9Adjusting nut
The hollow rocker shaft is located in the camshaft carrier in six fixed mountings which sit above the camshaft. Six bolts
are used to lock the rocker shaft to the camshaft carrier. The front rocker shaft bearing has a ring dowel located at the
front rocker shaft mounting of the camshaft carrier for rocker shaft alignment. Two circlips hold each rocker arm in
position at the relevant positions on the rocker shaft.
The rocker shaft from a pre EU3 model must not be fitted to an EU3 engine. This is because the stroke of the
EU3 injector has increased which requires the rocker to articulate over a larger angle.
The camshaft end of each rocker arm features a roller which is free to rotate about a pin which passes through two
webs in the rocker arm, the roller pins are held in place by an interference fit retention slug passing through a hole in
the front web of each rocker arm.
To correctly function against the higher injection loads of the EU3 engine the geometry of the contact between the
injector pushrod and rocker arm adjusting screw has been modified. Both designs of adjusting screw are separately
available with the EU3 version being identified by an engraved dimple in the slotted end.
Rocker shaft and rocker arm lubrication is splash and channel fed via pressurised oil flowing through galleries in the
cylinder head and through the rocker shaft.

ENGINE - TD5
DESCRIPTION AND OPERATION 12-1-25
Inlet and exhaust valves
The inlet and exhaust valves are mounted directly above the engine block cylinders.
Each valve is a forged and ground solid one-piece head and stem which is hardened by heat treatment. The stems
are chrome-plated then ground for improved heat transfer, wear resistance and smooth operation. It is not possible
to recut the valve's face angle, but the valves can be lapped to their seats using grinding paste.
The valve springs are made from spring steel and are of the parallel single-coil type. The bottom end of the spring
rests on the flange of a spring seal which has a centre bore that locates on a recess ground into the lower valve stem.
The top end of the spring is held in place by a spring retainer which is held in position at the top end of the valve stem
by split taper collets. The taper collets have grooves on the internal bore that locate to grooves ground into the upper
stems of the valves.
The valve seats and valve guides are sintered and are interference fit into the cylinder head. The valve seats and
guides are non-serviceable.
Finger followers and Lash adjusters
1Valve stem
2Finger follower
3Lash adjuster plunger
4Oil supply hole
5Lash adjuster body
The valves are operated through finger followers and lash adjusters, actuated by the camshaft lobes. When the
camshaft lobe presses down on the top of a finger follower roller mechanism, the respective valve is forced down
opening the effected inlet or exhaust port.
The lash adjuster body contains a plunger and two chambers for oil feed and pressurised oil. Pressurised oil is
supplied to the lash adjusters via the oil galleries in the cylinder head and through a hole in the side of the lash adjuster
body. The oil passes into a feed chamber in the lash adjuster then through to a separate pressure chamber via a one
way ball valve. Oil flow from the pressure chamber is determined by the amount of clearance between the lash
adjuster outer body and the centre plunger, oil escapes up the side of the plunger every time the lash adjuster is
operated, the downward pressure on the plunger forcing a corresponding amount of oil in the lash adjuster body to
be displaced. When the downward pressure from the camshaft and finger follower is removed (i.e. after the trailing
flank of the camshaft lobe has passed), oil pressure forces the lash adjuster's plunger up again. This pressure is not
sufficient to affect the valve operation, but eliminates the clearance between the finger follower and top of the valve
stem.

ENGINE - TD5
12-1-28 DESCRIPTION AND OPERATION
Tensioner adjuster
1Oil supply hole
2Tensioner adjuster body
3Tensioner adjuster plunger
4Sealing ring
The tensioner adjuster is hydraulically operated, oil enters the adjuster from the pressurised oil supply flowing through
the cylinder head to operate a plunger which pushes against a pivoting plastic tensioner arm. The lateral movement
in the tensioner arm causes the timing chain to tension and consequently compensation for chain flutter and timing
chain wear is automatically controlled. The adjuster is located at the front right hand side of the cylinder head, just
above the timing chain cover and below the vacuum pump oil feed port. The adjuster body is threaded and screws
into a tapping in the cylinder head. Holes are contained in the adjuster body to receive oil from the cylinder head
galleries, the oil pressure is used to force the plunger out of the adjuster body to press the tensioner arm against the
timing chain and so using the oil trapped in the adjuster body to perform as a damper.
The internal damping of the hydraulic tensioner is tuned for each application. This means that pre EU3 and EU3
components are not interchangeable.
Drive train sprockets
The camshaft sprocket has a double row of teeth which locate with the duplex timing chain. The sprocket is fitted to
the camshaft by three bolts.
The oil pump sprocket is located on the front of the oil pump housing by a single retaining bolt. The sprocket has a
single row of teeth which locates on the oil pump chain.
The crankshaft sprocket contains three rows of teeth, the rear row locates on the single oil pump chain and the front
two rows locate with the duplex timing chain. The crankshaft sprocket has a slot in its internal diameter which locates
with the Woodruff key on the crankshaft. The front of the crankshaft sprocket has a timing mark.
As a consequence of thicker chain links being used on EU3 models, the thickness of the camshaft and crankshaft
sprocket teeth has been reduced. Individual pre EU3 and EU3 components are therefore not interchangeable.

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.

ENGINE - TD5
DESCRIPTION AND OPERATION 12-1-31
Oil cooler / Filter flow (thermostat open)
1To cylinder block main gallery (from rear of oil
cooler housing)
2Oil cooler housing
3Oil pressure switch
4Full-flow filter
5Centrifuge filter6Return to sump
7Flow from oil pump (via cylinder block)
8Oil cooler matrix

ENGINE - TD5
12-1-32 DESCRIPTION AND OPERATION
When the engine temperature is below 74° C, the thermostat in the full-flow filter housing is closed and a proportion
of the oil flow to the main oil gallery is diverted to the oil cooler to supply an oil feed to the turbocharger bearings. Oil
passes through the oil cooler to the front gallery in the oil cooler housing where there is a tapping to connect the feed
pipe to the turbocharger. Oil used by the turbocharger bearings is returned to the sump through an oil drain pipe which
connects to a port in the LH side of the cylinder block.
The remainder of the oil flow leaving the full-flow filter outlet is passed into the cylinder block via a port at the rear of
oil cooler rear gallery.
When the oil temperature rises above 74
° C the thermostat in the full-flow filter adaptor housing begins to open to
allow a proportion of the oil from the full-flow filter to pass through the oil cooler before it reaches the main oil gallery
in the cylinder block. In this instance, oil supply to the turbocharger bearings is fed directly from the full-flow filter
without first passing through the oil cooler. Between 74
° C and 88° C the thermostat valve plunger opens by about
9mm to allow proportionally more oil to flow through the oil cooler before being passed to the cylinder block main oil
delivery gallery. Above 88
°C the thermostat valve continues to open by about 1mm for every 10° C increase in
temperature until the valve is fully open, when all the oil flow to the cylinder block is forced to pass to the cylinder block
via the oil cooler.
An oil pressure switch is located in a port in the rear gallery of the oil cooler housing to sense the oil pressure level
before flow enters the main oil gallery in the engine block. A warning lamp in the instrument cluster is switched on if
the oil pressure is detected as being too low.

+ INSTRUMENTS, DESCRIPTION AND OPERATION, Description.
Drillings from the cylinder block main oil gallery direct oil to the crankshaft main bearings and cross drillings in the
crankshaft direct oil to the big-end bearings. An additional five drillings in the cylinder block supply oil at reduced
pressure to the oil squirt jets for piston cooling and gudgeon pin lubrication.
Oil supply from the cylinder block is then passed to the cylinder head galleries through a non-return valve which is
included as an integral item in the lower face of the cylinder head.

ENGINE - TD5
12-1-62 REPAIRS
Valve - relief - oil pressure
$% 12.60.56
Remove
1.Remove sump gasket.

+ ENGINE - Td5, REPAIRS, Gasket -
sump.
2.Remove and discard plug from oil pump
housing.
3.Remove spring and valve.
Refit
1.Clean valve, spring and plug.
2.Clean valve seating inside oil pump housing.
3.Check valve and bore for scoring and
corrosion. Light scoring may be removed using
grade 600 emery cloth soaked in oil.
4.Check spring for distortion, check free length of
spring: Spring free length = 42.00 mm (1.65 in).
CAUTION: Renew relief valve as an
assembly.
5.Lubricate valve and seating.
6.Fit valve and spring to pump.
7.Apply Loctite 243 sealant to threads of new
plug.
CAUTION: Do not attempt to fit original
plug.
8.Fit oil pump pressure relief valve plug and
tighten to 23 Nm (17 lbf.ft).
9.Fit sump gasket.

+ ENGINE - Td5, REPAIRS, Gasket -
sump.
10.Check engine oil level, top-up if necessary.
Switch - oil pressure
$% 12.60.50
Remove
1.Remove fixings and remove engine acoustic
cover.
2.Remove 3 bolts and remove exhaust manifold
heat shield.
3.Disconnect multiplug from oil pressure switch.
4.Position container below switch to catch oil
spillage.
5.Remove oil pressure switch from oil cooler
housing.

ENGINE - TD5
REPAIRS 12-1-63
Refit
1.Clean oil pressure switch threads.
2.Fit oil pressure switch and tighten to 15 Nm (11
lbf.ft).
3.Connect multiplug to oil pressure switch.
4.Position exhaust manifold heatshield and
tighten M6 bolts to 9 Nm (7 lbf.ft) and M8 bolts
to 25 Nm (18 lbf.ft).
5.Fit and secure engine acoustic cover.
6.Top up engine oil.

+ MAINTENANCE, PROCEDURES,
Engine oil - diesel engine.
Cooler - engine oil
$% 12.60.68
Remove
1.Drain cooling system.

+ COOLING SYSTEM - Td5,
ADJUSTMENTS, Drain and refill.
2.Remove centrifuge assembly.

+ ENGINE - Td5, REPAIRS, Gasket -
centrifuge oil drain pipe.
3.Remove clutch housing bolt and release
coolant pipe from rear of engine.
4.Release clip and coolant hose from oil cooler.
5.Disconnect multiplug from oil pressure switch.
6.Remove full-flow oil filter element using a
suitable strap wrench.
7.Remove 3 bolts, remove oil filter adaptor
housing and discard gasket.
8.Remove 7 bolts, remove oil cooler and discard
gasket.
9.Remove oil pressure switch.