height LAND ROVER DISCOVERY 1999 User Guide

MAINTENANCE
10-28 PROCEDURES
Check – Height sensors
SLS height sensors
1.Check height sensors for condition and
security.
2.Check electrical harness for chafing and
damage.
Front and rear axle suspension links
Check
Rear suspension
Front suspension
1.Check condition of front and rear axle
suspension link mounting rubbers.
2.Check security of fixings.

+ TORQUE WRENCH SETTINGS,
Front suspension.

+ TORQUE WRENCH SETTINGS, Rear
suspension.

ENGINE - V8
12-2-62 OVERHAUL
10.Remove cylinder head gasket.
CAUTION: Support both ends of cylinder
head on blocks of wood.
Inspect
1.Clean mating faces of cylinder block and head
using suitable gasket removal spray and a
plastic scraper, ensure that bolt holes in block
are clean and dry.
CAUTION: Do not use a metal scraper or
machined surfaces may be damaged.
2.Check head and block faces for warping and
pitting.
lMaximum cylinder head warp = 0.05 mm
(0.002 in).
Note: Cylinder head can be refaced to 0.50
mm (0.02 in) maximum below head height –
See cylinder head overhaul.
3. Models with SAI: Using a 5/8 in x 20 TPI (
threads per inch) UNF tap having a class 2A
thread, remove deposits from secondary air
injection adapter tappings in cylinder head.
CAUTION: Ensure that tap used has 20 TPI.Reassembly
1.Ensure that cylinder head bolt holes are clean
and dry.
2.Fit cylinder head gasket with the word TOP
uppermost.
CAUTION: Gaskets must be fitted dry.
3.Carefully fit cylinder head and locate on
dowels.
4.Lightly lubricate new cylinder head bolt threads
with clean engine oil.
5.Noting that bolts 1, 3 and 5 are longer than the
remainder, fit bolts and tighten in the sequence
shown to 20 Nm (15 lbf.ft) then turn through 90
°, then a further 90 °. CAUTION: Do not
tighten bolts 180° in one operation.
6. Models with SAI: Fit new air injection adapters
and using a 9 mm hexagonal drive bit, tighten
to 33 Nm (24 lbf.ft).
CAUTION: Do not use an air tool to tighten
adapters.
7.Clean the push rods, Lubricate ends of push
rods with clean engine oil, and fit in their
removed order.
8.Clean bases of rocker pillars and mating faces
on cylinder head.
9.Clean contact surfaces on rockers, valves and
push rods.
10.Lubricate contact surfaces and rocker shaft
with clean engine oil.
11.Fit rocker shaft assembly and engage push
rods.
12.Fit rocker shaft bolts and progressively tighten
to 40 Nm (30 lbf.ft).
13.Connect ht leads to spark plugs in their correct
fitted order.
14. RH cylinder head: Position alternator
mounting bracket, fit bolts and tighten to 40 Nm
(30 lbf.ft).
15. RH cylinder head: Fit auxiliary drive belt
tensioner.
16.Fit inlet manifold gasket.

+ ENGINE - V8, OVERHAUL, Gasket -
inlet manifold.

ENGINE - V8
OVERHAUL 12-2-63
Cylinder head - overhaul
$% 12.29.19.01
Disassembly
1.Remove cylinder head gasket.

+ ENGINE - V8, OVERHAUL, Gasket -
cylinder head.
2.Loosen screw on tool LRT-12-034.
3.Fit tool LRT-12-034 to valve and tighten screw
to compress valve spring sufficiently to release
collets from valve spring cap.
4.Remove 2 collets and release valve spring
compressor.
5.Remove valve spring cap and valve spring.
6.Remove valve from cylinder head.
7.Remove and discard valve stem oil seal.
8.Repeat above operations for remaining valves.
9.Keep valves, springs, caps and collets in their
fitted order. Inspect
1.Clean mating faces of cylinder block and head
using suitable gasket removal spray and a
plastic scraper, ensure that bolt holes in block
are clean and dry.
CAUTION: Do not use a metal scraper or
machined surfaces may be damaged.
2.Clean cylinder head, valve springs, valves and
inlet valve guide bores. Ensure all loose
particles of carbon are removed on completion.
3. Models with SAI: Using a 5/8 in x 20 TPI (
threads per inch) UNF tap having a class 2A
thread, remove deposits from secondary air
injection adapter tappings in cylinder head.
CAUTION: Ensure that tap used has 20 TPI.
4.Check head and block faces for warping and
pitting. Maximum warp = 0.05 mm (0.002 in).
5.Check cylinder head height at each end of
head. Renew a head which is outside limits.
a22.94 mm (0.903 in) - New
b62.56 mm (2.463 in) - New

ENGINE - V8
12-2-64 OVERHAUL
6.Cylinder head can be refaced to 0.50 mm (0.02
in) max. below head height.
7.Remove carbon deposits from exhaust valve
guide using a 8.70 mm (0.34 in) diameter
reamer inserted from combustion face side of
cylinder head.
NOTE: Modified inlet valves, exhaust valves
and valve guides were fitted to 4.0 litre engines
from the following engine numbers: 55D
05678A; 56D 50788A and 97D 05505A and are
fitted to all 4.6 litre engines.
8.Modified inlet valves may be identified by
measuring the distance 'A' from the valve head
face to the top of the undercut on the valve
stem:
lEarly valves = 29.5 to 30.5 mm (1.16 to 1.20
in)
lLater valves = 32.5 to 33.5 mm (1.28 to 1.32
in)9.Modified exhaust valves may be identified as
follows:
lEarly valves 'A' – Chrome finish
lLater valves 'B' – Black nitrided finish
10.Modified valve guides are 5 mm (0.211 in)
shorter than the early type, the overall length is
now 57 mm (2.24 in); the reduction in length
being the distance the guide protrudes into the
combustion chamber side of the cylinder head.
NOTE: The modified valves and guides may be
fitted to 4.0 litre engines prior to the above
numbers in cylinder sets. Early type valves will
continue to be supplied for early 4.0 litre
engines but if valve guides are found to be
worn, the later valves and guides must be fitted.

ENGINE - V8
OVERHAUL 12-2-65
11.Check the following valve dimensions. Renew
valves as necessary.
lValve head diameter 'A': Inlet = 39.75 to
40.00 mm (1.56 to 1.57 in).
lValve head diameter 'A': Exhaust = 34.23 to
34.48 mm (1.35 to 1.36 in).
lValve stem diameter 'B': Inlet = 8.664 to
8.679 mm (0.341 to 0.342 in).
lValve stem diameter 'B': Exhaust – 4.0 litre
engines up to engine nos. 55D 05677A; 56D
50787A and 97D 05504A = 8.651 to 8.666
mm (0.340 to 0.341 in).
lValve stem diameter 'B': Exhaust – 4.0 litre
engines from engine nos. 55D 05678A; 56D
50788A and 97D 05505A and all 4.6 litre
engines = 8.641 to 8.656 mm (0.340 to
0.341 in)
12.Check installed height of valve.
lValve installed height, end of valve to base
of spring seat, 'C' = 44.163 to 45.288 mm
(1.741 to 1.802 in).
13.Check condition of valve springs. Valve
springs must be replaced as a complete
set.
lValve spring free length = 48.30 mm (1.90
in).
lValve spring fitted length = 40.40 mm (1.59
in).
l Spring load - valve closed = 339 ± 10 N (76
± 2.25 lbf).
lSpring load - valve open = 736 ± 10 N (166
± 2.25 lbf).
14.Check valve stem to guide clearance using the
following procedures:
15.Insert each valve into its respective guide.
16.Extend valve head approximately 13 mm (0.6
in) out of valve seat and position a DTI gauge
to rear of valve head.
17.Move valve towards front of cylinder head and
zero DTI gauge ensuring that stylus of gauge
remains in contact with valve head.
18.Move valve towards rear of cylinder head and
record gauge reading to give valve stem to
guide clearance.
l Valve stem to guide clearance 'D': Inlet =
0.025 to 0.066 mm (0.001 to 0.002 in).
l Valve stem to guide clearance 'D': Exhaust
– 4.0 litre engines up to engine nos. 55D
05677A; 56D 50787A; 97D 05504A = 0.038
to 0.078 mm (0.0015 to 0.003 in).
lValve stem to guide clearance 'D': Exhaust
– 4.0 litre engines from engine nos. 55D
05678A; 56D 50788A; 97D 05505A and all
4.6 litre engines = 0.048 to 0.088 mm
(0.0019 to 0.0035 in).
19.Renew valve guides as necessary. 20.Using valve guide remover tool LRT-12-037
press valve guide into combustion face side of
cylinder head.
21.Lubricate new valve guide with engine oil and
with tapered portion of guide leading, insert
guide from valve spring side of head.
Note: Service valve guides are 0.025 mm
(0.001 in) oversize on outside diameter to
ensure an interference fit.
22.Fully fit guide using tool LRT-12-039A and
distance piece tool LRT-12-208
lValve guide installed height 'A' = 15.00 mm
(0.590 in).
23.Ream valve guide to 8.70 mm (0.342 in).
Note: Service valve guides are supplied with an
internal diameter of 8.1 mm 0.025 mm (0.319 in).
24.Position cylinder head stands and mount
cylinder head on stands.
25.Check valve seat insert for pitting, burning,
cracks and wear. Replace as necessary.
Service valve seat inserts are available 0.025
mm (0.001 in) oversize on outside diameter to
ensure interference fit.

ENGINE - V8
12-2-66 OVERHAUL
26.Remove worn valve seat.
CAUTION: Take care not to damage the
counterbore in the cylinder head when
removing valve seats.
27.Heat cylinder head evenly to approximately
120° C (250°F).
WARNING: Handle the hot cylinder head
with care.
28.Using a suitable mandrel, press new insert fully
into counterbore.
29.Allow cylinder head to air cool.
CAUTION: Renew worn valve guides and/or
valve seats before lapping the valves.
30.Recut valve seat in head and lap in valves
using fine paste.
31.Coat valve with a small quantity of engineer's
blue, insert valve and press into position
several times without rotating. Seating position
should be in centre of valve face. 32.Check valve installed height if valve seats have
been refaced or renewed.
lValve installed height, end of valve to base
of spring seat, 'A' = 44.16 to 45.29 mm (1.74
to 1.80 in).
33.Reface valves as necessary. If a valve has to
be ground to a knife-edge to obtain a true seat,
renew valve.
34.Cut valve seats using suitable cutters:
lValve seat angle 'A' = 45°.
lValve seat insert diameter 'B' Inlet = 36.83
mm (1.45 in).
lValve seat insert diameter 'B' Exhaust =
31.50 mm (1.24 in).
lSeating width 'C' - Inlet = 0.89 to 1.4 mm
(0.035 to 0.055 in).
lSeating width 'C' - Exhaust = 1.32 to 1.83
mm (0.052 to 0.072 in).
lAngle 'D' = 70° .
lAngle 'E' = 46° to 46° 25'.
lAngle 'F' = 20° .

EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-39
Evaporative Emission Control Operation
Fuel vapour is stored in the activated charcoal (EVAP) canister for retention when the vehicle is not operating. When
the vehicle is operating, fuel vapour is drawn from the canister into the engine via a purge control valve. The vapour
is then delivered to the intake plenum chamber to be supplied to the engine cylinders where it is burned in the
combustion process.
During fuel filling the fuel vapour displaced from the fuel tank is allowed to escape to atmosphere, valves within the
fuel filler prevent any vapour escaping through to the EVAP canister as this can adversely affect the fuel cut-off height.
Only fuel vapour generated whilst driving is prevented from escaping to atmosphere by absorption into the charcoal
canister. The fuel filler shuts off to leave the tank approximately 10% empty to ensure the ROVs are always above
the fuel level and so vapour can escape to the EVAP canister and the tank can breathe. The back pressures normally
generated during fuel filling are too low to open the pressure relief valve, but vapour pressures accumulated during
driving are higher and can open the pressure relief valve. Should the vehicle be overturned, the ROVs shut off to
prevent any fuel spillage.
Fuel vapour generated from within the fuel tank as the fuel heats up is stored in the tank until the pressure exceeds
the operating pressure of the two-way valve. When the two-way valve opens, the fuel vapour passes along the vent
line from the fuel tank (via the fuel tank vapour separator) to the evaporation inlet port of the EVAP canister. The fuel
tank vents between 5.17 and 6.9 kPa.
Fuel vapour evaporating from the fuel tank is routed to the EVAP canister through the fuel vapour separator and vent
line. Liquid fuel must not be allowed to contaminate the charcoal in the EVAP canister. To prevent this, the fuel vapour
separator fitted to the fuel neck allows fuel to drain back into the tank. As the fuel vapour cools, it condenses and is
allowed to flow back into the fuel tank from the vent line by way of the two-way valve.
The EVAP canister contains charcoal which absorbs and stores fuel vapour from the fuel tank while the engine is not
running. When the canister is not being purged, the fuel vapour remains in the canister and clean air exits the canister
via the air inlet port.
The engine management ECM controls the electrical output signal to the purge valve. The system will not work
properly if there is leakage or clogging within the system or if the purge valve cannot be controlled.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
When the engine is running, the ECM decides when conditions are correct for vapour to be purged from the EVAP
canister and opens the canister purge valve. This connects a manifold vacuum line to the canister and fuel vapour
containing the hydrocarbons is drawn from the canister's charcoal element to be burned in the engine. Clean air is
drawn into the canister through the atmosphere vent port to fill the displaced volume of vapour.
The purge valve remains closed below preset coolant and engine speed values to protect the engine tune and
catalytic converter performance. If the EVAP canister was purged during cold running or at idling speed, the additional
enrichment in the fuel mixture would delay the catalytic converter light off time and cause erratic idle. When the purge
valve is opened, fuel vapour from the EVAP canister is drawn into the plenum chamber downside of the throttle
housing, to be delivered to the combustion chambers for burning.
The purge valve is opened and closed in accordance with a pulse width modulated (PWM) signal supplied from the
engine management ECM. The system will not work properly if the purge valve cannot be controlled. Possible failure
modes associated with the purge valve are listed below:
lValve drive open circuit.
lShort circuit to vehicle supply or ground.
lPurge valve or pipework blocked or restricted.
lPurge valve stuck open.
lPipework joints leaking or disconnected.
Possible symptoms associated with a purge valve or associated pipework failure is listed below:
lEngine may stall on return to idle if purge valve is stuck open.
lPoor idling quality if the purge valve is stuck open
lFuelling adaptions forced excessively lean if the EVAP canister is clear and the purge valve is stuck open.
lFuelling adaptions forced excessively rich if the EVAP canister is saturated and the purge valve is stuck open.
lSaturation of the EVAP canister if the purge valve is stuck closed.

FUEL DELIVERY SYSTEM - V8
DESCRIPTION AND OPERATION 19-2-5
Fuel tank breather system (all markets except NAS)
The filler tube incorporates a tank vent which allows air and fuel vapour displaced from the tank when filling to vent to
atmosphere via the filler neck. A relief valve in the vent line to the EVAP canister prevents vapour escaping through
the canister during filling. This prevents the customer overfilling the tank and maintains the correct fuel cut-off level.
The filler tube also incorporates an integral Liquid Vapour Separator (LVS). During normal driving excess fuel vapour
is passed via the vent line into the EVAP canister. To prevent the canister from being overloaded with fuel vapour,
especially in hot climates, the vapour is given the opportunity to condense in the LVS. Fuel which condenses in the
LVS flows back into the tank through the ROV's.
A breather spout within the tank controls the tank 'full' height. When fuel covers the spout it prevents fuel vapour and
air from escaping from the tank. This causes the fuel to 'back-up' in the filler tube and shuts off the filler gun. The
position of the spout ensures that when the filler gun shuts off, a vapour space of approximately 10% of the tanks total
capacity remains. This vapour space ensures that Roll Over Valves (ROV's) are always above the fuel level and the
vapour can escape and allow the tank to breathe.
The pressure relief valve fitted in the vent line to the EVAP canister prevents the customer trickle filling the tank.
Trickle filling greatly reduces the vapour space in the tank which in turn affects the tank's ability to breathe properly,
reducing engine performance and safety. When filling the tank, the pressures created are too low to open the pressure
relief valve, preventing the customer from trickle filling the tank. Vapour pressures created during driving are higher
and will open the valve allowing vapour to vent to the EVAP canister.
Four ROV's are welded onto the top surface of the tank. Each ROV is connected by a tube to the main vent line to
the EVAP canister. The ROV's allow fuel vapour to pass through them during normal vehicle operation. In the event
of the vehicle being overturned the valves shut-off, sealing the tank and preventing fuel from spilling from the vent line.
Fuel tank breather system (NAS)
The filler tube incorporates a tank vent which allows air and fuel vapour displaced from the tank when filling to vent to
atmosphere via the filler neck. A filler cap operated valve within the fuel filler neck prevents vapour escaping through
the EVAP canister during filling. This prevents the customer overfilling the tank and maintains the correct fuel cut-off
level.
The filler tube also has an 'L' shaped, stainless steel Liquid Vapour Separator (LVS). During normal driving excess
fuel vapour is passed via the vent line into the EVAP canister. To prevent the canister from being overloaded with fuel
vapour, especially in hot climates, the vapour is given the opportunity to condense in the LVS. Fuel which condenses
in the LVS flows back into the tank via the LVS vent line and through the Roll Over Valves (ROV's).
For NAS vehicles with vacuum type EVAP system leak detection capability, a small tube is located alongside the filler
tube and terminates near to the filler neck. The tube is connected to the On Board Diagnostics (OBD) pressure sensor
in the fuel pump and provides the sensor with a reading of atmospheric pressure to compare against the tank
pressure.

+ EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Emission Control Systems.
A breather spout within the tank controls the tank 'full' height. When fuel covers the spout it prevents fuel vapour and
air from escaping from the tank. This causes the fuel to 'back-up' in the filler tube and shuts off the filler gun. The
position of the spout ensures that when the filler gun shuts off, a vapour space of approximately 10% of the tanks total
capacity remains. This vapour space ensures that the ROV's are always above the fuel level and the vapour can
escape to the LVS and allow the tank to breathe.
The filler cap operated valve closes the vent line to the EVAP canister to prevent the customer trickle filling the tank.
Trickle filling greatly reduces the vapour space in the tank which in turn affects the tank's ability to breathe properly,
reducing engine performance and safety. When filling the tank, the removal of the filler cap closes the valve and the
vent line preventing the customer from trickle filling the tank. When the cap is installed the valve is opened by the cap
allowing vapour to vent to the EVAP canister.
The four ROV's are welded inside the top surface of the tank. Each ROV is connected internally in the tank by a tube
to the LVS. The ROV's allow fuel vapour to pass through them during normal vehicle operation. In the event of the
vehicle being overturned the valves shut-off, sealing the tank and preventing fuel from spilling from the vent line into
the LVS.

TRANSFER BOX - LT230SE
OVERHAUL 41-45
4. 03 Model Year onwards: Using tools LRT-99-
003 and LRT-41-006, fit bearing tracks to
intermediate gears ensuring that tracks are fully
seated against shoulders in gears.
5.Using a micrometer, measure the width of each
bearing inner track. 6.Record each reading as measurement 'A' and
'B', both measurements should fall within the
range of 21.95 to 22.00 mm (0.864 to 0.866 in).
7.Fit inner bearing track 'A' onto tool LRT-41-017
and position intermediate gear cluster onto
bearing 'A'.
8.Fit inner bearing track 'B' to intermediate gear,
apply finger pressure to bearing inner track
and rotate intermediate gear 5 to 10 turns to
settle in bearing rollers.
9.Attach a DTI to base of tool LRT-41-017 , zero
gauge on top of tool post and take 2
measurements at 180° of the step height
between the top of the tool post and the
bearing inner track. Take an average of the two
readings and record this as measurement 'C'.
Measurement 'C' should be in the range of 0.15
to 0.64 mm (0.006 to 0.025 in).
10.Using the formula 103.554 mm (4.0769 in) -'A'-
'B'-'C', calculate the length of bearing spacer
required. From the result of the calculation
round DOWN to the nearest length of spacer
available to give a correct bearing pre-load of
0.005 mm (0.002 in). 40 spacers are
available ranging in length from 58.325 mm
(2.296 in) to 59.300 mm (2.335 in) rising in
increments of 0.025 mm (0.001 in).
11.Remove intermediate gear assembly from tool
LRT-41-017.
12.Lubricate and fit bearings and selected spacer
to intermediate gear.
13.Position tool LRT-41-004 through bearings
and spacer.

TRANSFER BOX - LT230SE
41-60 OVERHAUL
31.Position depth block tool LRT-41-014/2 and
cross bar tool LRT-41-014/1 to front output
housing.
32.Position DTI to tool LRT-41-014/1 cross bar
and zero DTI on depth block.
33.Position DTI to cross bar and record reading
obtained.
34. Using the formula: 3.05 mm (0.120 in)+B-
A=D where: B=Height difference recorded
between depth block and cross bar.
A=Average of readings to differential front
bearing outer track. D=Thickness of shim
required to give differential bearing pre-load of
0.05 mm (0.002 in).
35.From the resultant figure obtained, select
appropriate thickness shim from the range
available.
36.Shims are available from 2.00 to 3.25 mm
(0.08 to 0.13 in) thickness, rising in increments
of 0.05 mm (0.002 in). 37.Heat the front output housing to 100°C (210°F)
and fit new output shaft bearing using tool
LRT-41-011.
38.Allow housing to air cool.
39.Fit new bearing retaining circlip ensuring that
circlip is fully seated.
40.Using tool LRT-41-012, fit new output shaft oil
seal. Check that oil seal is just contacting
circlip.
CAUTION: Oil seal must be fitted dry.