Land Rover V8 engine 4.0, 4.6 litre. Manual — part 11
ENGINE
26
OVERHAUL
Camshaft and tappets - inspection
1. Thoroughly clean all components.
2. Inspect camshaft bearing journals and lobes
for signs of wear, pitting, scoring and
overheating.
3. Support camshaft front and rear bearings on
vee blocks, and using a DTI, measure
camshaft run-out on centre bearing:
Maximum permitted run-out = 0.05 mm (0.002
in)
4. Inspect thrust plate for wear, replace plate if
wear is evident.
5. Clean and inspect tappets. Check for an even,
circular wear pattern on the camshaft contact
area. If contact area is pitted or a square wear
pattern has developed, tappet must be
renewed.
6. Inspect tappet body for excessive wear or
scoring. Replace tappet if scoring or deep wear
patterns extend up to oil feed area. Clean and
inspect tappet bores in cylinder block.
7. Ensure that tappets rotate freely in their
respective bores.
8. Inspect pushrod contact area of tappet, replace
tappet if surface is rough or pitted.
Camshaft and tappets - refit
NOTE: If a replacement camshaft is to be
fitted, ensure colour coding is correct.
Camshafts fitted to 4.0 litre engines are
colour coded ORANGE whilst those fitted to 4.6
litre engines are colour coded RED.
1. Lubricate camshaft journals with engine oil and
carefully insert camshaft into cylinder block.
2. Fit camshaft thrust plate, fit bolts and tighten to
25 Nm (18 lbf.ft).
NOTE: If camshaft or thrust plate has been
replaced, it will be necessary to re-check
camshaft end-float.
3. Immerse tappets in engine oil. Before fitting,
pump the inner sleeve of tappet several times
using a pushrod to prime tappet; this will
reduce tappet noise when engine is first
started.
4. Lubricate tappet bores with engine oil and fit
tappets in removed order.
NOTE: Some tappet noise may still be
evident on initial start-up. If necessary, run
the engine at 2500 rev/min for a few
minutes until noise ceases.
5. Fit timing chain and gears.
6. Fit rocker shaft assemblies.
ENGINE
OVERHAUL
27
PISTONS, CONNECTING RODS, PISTON RINGS
AND CYLINDER BORES
Pistons and connecting rods - remove
1. Remove cylinder head(s).
2. Remove big-end bearings.
3. Remove carbon ridge from top of each cylinder
bore.
4. Suitably identify each piston to its respective
cylinder bore.
5. Push connecting rod and piston assembly to
top of cylinder bore and withdraw assembly.
6. Repeat above procedure for remaining pistons.
CAUTION: Big-end bearing shells must be
replaced whenever they are removed.
Piston rings - remove
1. Using a suitable piston ring expander, remove
and discard piston rings.
2. Remove carbon from piston ring grooves.
NOTE: Use an old broken piston ring with
a squared-off end.
CAUTION: Do not use a wire brush.
ENGINE
28
OVERHAUL
Piston rings - inspection
1. Temporarily fit new compression rings to
piston.
NOTE: If replacement pistons are to be
fitted, ensure rings are correct for piston.
The 2nd compression ring marked ’TOP’ must be
fitted, with marking uppermost, into second
groove. The 1st compression ring fits into top
groove and can be fitted either way round.
2. Check compression ring to groove clearance:
1st compression ring A = 0.05 to 0.10 mm
(0.002 to 0.004 in).
2nd compression ring B = 0.05 to 0.10 mm
(0.002 to 0.004 in).
3. Insert piston ring into its relevant cylinder bore,
held square to bore with piston and check ring
gaps.
1st compression ring = 0.3 to 0.5 mm (0.01 to
0.02 in)
2nd compression ring = 0.40 to 0.65 mm
(0.016 to 0.03 in)
Oil control ring rails = 0.38 to 1.40 mm (0.014
to 0.05 in)
4. Retain rings with their respective pistons.
Pistons- remove
1. Clamp hexagon body of LRT-12-013 in vice.
2. Screw large nut back until flush with end of
centre screw.
3. Push centre screw forward until nut contacts
thrust race.
4. Locate remover/replacer adapter
LRT-12-126/2 with its long spigot inside bore
of hexagon body.
5. Position remover/replacer adapter
LRT-12-126/3 on LRT-12-126/2 with cut-out
facing away from body of LRT-12-013 .
6. Locate piston and connecting rod assembly on
centre screw and up to adapter LRT-12-126/2.
7. Position cut-out of adapter LRT-12-126/3 to
piston.
CAUTION: Ensure cut-out does not
contact gudgeon pin.
8. Fit remover/replacer bush LRT-12-126/1 on
centre screw with flanged end away from
gudgeon pin. Screw stop nut on to centre
screw.
9. Lock the stop nut securely with lockscrew.
10. Push connecting rod to right to locate end of
gudgeon pin in adapter LRT-12-126/2.
11. Screw large nut up to LRT-12-013 .
12. Hold lockscrew and turn large nut until
gudgeon pin is withdrawn from piston.
13. Dismantle tool and remove piston, connecting
rod and gudgeon pin.
NOTE: Keep each piston and gudgeon pin
with their respective connecting rod.
14. Repeat above operation for remaining pistons.
ENGINE
OVERHAUL
29
Pistons - inspection
1. Clean carbon from pistons.
2. Inspect pistons for distortion, cracks and
burning.
3. Measure and record piston diameter at 90
°
to
gudgeon pin axis and 10 mm (0.4 in) from
bottom of skirt.
4. Check gudgeon pin bore in piston for signs of
wear and overheating.
NOTE: Pistons fitted on production are
graded ’A’ or ’B,’ the grade letter is
stamped on the piston crown.
Production piston diameter:
Grade A = 93.970 to 93.985 mm (3.700 to 3.7002 in)
Grade B = 93.986 to 94.00 mm (3.7003 to 3.701 in)
Grade B pistons are supplied as service
replacements. Worn cylinder liners fitted with grade
’A’ pistons may be honed to accept grade ’B’
pistons provided that specified cylinder bore and
ovality limits are maintained.
CAUTION: Ensure replacement pistons are
correct for the compression ratio of the
engine. The compression ratio will be
found on the cylinder block above the engine
serial number. Ensure that replacement
connecting rods are correct length for engine
being overhauled.
Connecting rod length between centres:
4.0 litre = 155.12 to 155.22 mm (6.10 to 6.11 in)
4.6 litre = 149.68 to 149.78 mm (5.89 to 5.91 in)
Gudgeon pins - inspection
NOTE: Gudgeon pins are only supplied as
an assembly with replacement pistons.
1. Check gudgeon pins for signs of wear and
overheating.
2. Check clearance of gudgeon pin in piston.
Gudgeon pin to piston clearance = 0.006 to
0.015 mm (0.0002 to 0.0006 in).
3. Check overall dimensions of gudgeon pin.
Overall length = 60.00 to 60.50 mm (2.35 to 2.4
in).
Diameter - measured at each end and centre
of pin = 23.995 to 24.00 mm (0.94 to 0.95 in).
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