1999 LAND ROVER DEFENDER Workshop Manual

12ENGINE
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DESCRIPTION AND OPERATION 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 cap 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 in grooves ground into
the upper stems of the valves.
The valve seats and valve guides are sintered and are an interference fit into the cylinder head. The valve seats
and guides are non-serviceable.
Finger followers and lash adjusters
1.Valve stem
2.Finger follower
3.Lash adjuster plunger4.Oil supply hole
5.Lash 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 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 effect the valve operation, but eliminates the clearance between the finger
follower and top of the valve stem.
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ENGINE
29
DESCRIPTION AND OPERATION Timing chain guides
1.Hydraulic tensioner
2.Adjustable tensioner arm
3.Duplex timing chain4.Camshaft sprocket
5.Fixed tensioner arm
6.Crankshaft sprocket
The crankshaft sprocket to camshaft sprocket timing chain is held taut by a tensioner arm acting on the slack side
of the chain. The tensioner is automatically adjusted by means of an hydraulically operated tensioner adjuster.
The drive side of the chain has a plastic guide attached to the front face of the cylinder block. The fixed guide is
attached to the front of the engine block by two bolts. The tensioner arm is fixed to the front of the cylinder block
by a single pivot bolt which allows the tensioner arm to pivot about its axis.
NOTE: The adjustable tensioner arm is not interchangeable between pre-EU3 and EU3 vehicles
due to a change in geometry on the EU3 version.
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12ENGINE
30
DESCRIPTION AND OPERATION CAMSHAFT COVER COMPONENTS
The camshaft cover 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
thirteen 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 and camshaft carrier.
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.
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 the 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. An
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.
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ENGINE
31
DESCRIPTION AND OPERATION Tensioner adjuster
1.Oil supply hole
2.Tensioner adjuster body3.Tensioner adjuster plunger
4.Sealing 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 act 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 with the oil pump drive 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 vehicles, the thickness of the camshaft and crankshaft
sprocket teeth has been reduced. Individual pre-EU3 and EU3 components are therefore not interchangeable.
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12ENGINE
32
DESCRIPTION AND OPERATION CYLINDER BLOCK FLOW
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ENGINE
33
DESCRIPTION AND OPERATION 1.Oil squirt jets (5 off)
2.Main oil delivery gallery
3.Inflow from oil cooler housing
4.Flow to oil cooler / filters (from oil pump via cylinder block)
5.Sump
6.Oil pick-up pipe
7.Flow from oil pump (relief-valve in housing)
8.Oil pump
9.Cross-drilling supply to main and crankshaft bearings
10.To cylinder head
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.
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12ENGINE
34
DESCRIPTION AND OPERATION OIL COOLER / FILTER FLOW
(THERMOSTAT OPEN)
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ENGINE
35
DESCRIPTION AND OPERATION 1.To cylinder block main gallery (from rear of oil cooler housing)
2.Oil cooler housing
3.Oil pressure switch
4.Full-flow filter
5.Centrifuge filter
6.Return to sump
7.Flow from oil pump (via cylinder block)
8.Oil cooler matrix
When the engine temperature is below 74°C, the thermostat in the full-flow filter adaptor 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 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 9 mm
(0.3 in) 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 (0.03 in) 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.
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.
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