spark plugs replace LAND ROVER DISCOVERY 1995 Workshop Manual

MAINTENANCE
5
MAINTENANCE 2.Clean or replace spark plugs as applicable.
3.It is essential that correct type of spark plugs are
fitted.
4.Incorrect grade of plugs may lead to piston
overheating and engine failure.
Remove
5.Disconnect battery negative lead. Remove H.T.
leads from spark plugs.
6.Remove plugs and washers.
7.When pushing leads onto plugs, ensure that
shrouds are firmly seated.Fitting H.T. leads
8.Ensure replacement H.T. leads are correctly
refitted as illustrated.
Failure to observe this instruction may result in
cross-firing between two closely fitted leads
which are consecutive in firing order.
3.9 V8
4.0 V8

Mpi
17
REPAIR 22.Raise vehicle
23.Remove 4 nuts securing downpipe to exhaust
manifold.
24.Release downpipe from exhaust manifold.
25.Collect gasket.
26.Release 4 screws and remove spark plug cover.
27.Release spark plug leads from spark plugs and
release from clips. Place aside.
28.Remove camshaft covers.
29.Remove timing belt.
See Camshaft Front Oil
Seal
30.Progressively loosen and remove 10 cylinder
head bolts in sequence shown.
31.Remove cylinder head complete with manifold,
place on blocks to prevent damage.
32.Remove and discard cylinder head gasket.
33.Remove location dowels from cylinder block.
34.Inspect cylinder head for damage, cracks and
burning.
35.Inspect cylinder block. Ensure that the oil
restrictor is clear and fitted below the block face.
36.Clean all traces of gasket material from head
and block mating faces, using release agent and
plastic scraper.
37.Check cylinder head and block faces for
warpage:
Longitudinal warp = 0.1 mm max.
Transverse warp = 0.1 mm max.
Diagonal warp = 0.1 mm max.
38.Decarbonize cylinder head and pistons if
necessary.
39.Clean cylinder head bolt threads with a wire
brush, check for damage, replace if necessary.
40.Check cylinder block threads by running bolts
into threads using fingers only. Clean any tight
threads using M11 x 1.5 mm tap. Remove all
traces of oil from bolt holes.

86ELECTRICAL
2
FAULT DIAGNOSIS LUCAS CONSTANT ENERGY IGNITION SYSTEM -
V8i
Preliminary checks
Inspect battery cables and connections to ensure they
are clean and tight. Check electrical condition of
battery.
Inspect all L.T. connections, ensure they are clean
and tight. Check H.T. leads are correctly positioned
and not shorting to ground against any engine
components. Wiring harness and individual cables
should be firmly fastened to prevent chaffing.
Pick-up air gap
Check air gap between pick-up limb and reluctor teeth
is 0.20 - 0.35 mm, using a non-ferrous gauge.
NOTE: Air gap is set initially at factory and
will only require adjusting if tampered with
or when pick-up module is replaced.
TEST 1:
H.T. Sparking
Remove coil/distributor H.T. lead from distributor
cover and hold approximately 6mm from engine block,
using suitable insulated pliers. Switch ignition 'On' and
operate starter.
Regular sparking indicates fault in H.T. distribution,
plugs, timing or fuelling, proceed to Test 6. If no spark
or weak spark occurs proceed to Test 2.TEST 2:
L.T. Voltage
Switch ignition 'On' - engine stationary.
(a) Connect voltmeter to points in circuit indicated
by V1 to V4 and make a note of voltage
readings.
(b) Compare voltages obtained with specified
values listed below:
Expected readings
V1 More than 12 volts.
V2 1 volt maximum below volts at V1.
V3 1 volt maximum below volts at V1.
V4 0 volt - 0.1 volt.
(c) If all readings are correct proceed to Test 3.
(d) Check incorrect reading(s) with chart to identify
area of possible faults, i.e. faults listed under
heading SUSPECT and rectify.
(e) If coil and amplifier is suspected, disconnect L.T.
lead at coil, repeat V3. If voltage is still incorrect,
fit new coil. If voltage is now correct, check L.T.
lead, if satisfactory fit new amplifier.
(f) If engine will not start proceed to Test 3.