Discovery 2. Manual — part 47

ENGINE - V8

OVERHAUL 12-2-61

Gasket - cylinder head

$% 12.29.02.01

Disassembly

1. Remove inlet manifold gasket.

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ENGINE - V8, OVERHAUL, Gasket -

inlet manifold.

2. RH cylinder head: Remove auxiliary drive belt

tensioner.

3. RH cylinder head: Remove bolts securing

alternator mounting bracket and remove
bracket.

4. Noting their fitted order, disconnect ht leads

from spark plugs.

5. Progressively remove 4 bolts securing the

rocker shaft and remove rocker shaft.

6. Remove push rods and store in their fitted

order.

7. Models with SAI: Using a 9 mm hexagonal

drive bit, remove 2 air injection adapters from
cylinder head; discard adapters.

To release the adapter thread locking agent
and prevent damage to the cylinder head,
remove the adapters by alternately loosening
then tightening slightly. Repeat this procedure
until adapters are removed.

CAUTION: Do not use air tools to remove
adapters.

8. Working in the sequence shown remove 10

bolts securing the cylinder head to block.
Discard the bolts.

9. Remove cylinder head.

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.

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Maximum 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.

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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.

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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.

a 22.94 mm (0.903 in) - New

b 62.56 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:

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Early valves = 29.5 to 30.5 mm (1.16 to 1.20
in)

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Later valves = 32.5 to 33.5 mm (1.28 to 1.32
in)

9. Modified exhaust valves may be identified as

follows:

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Early valves 'A' – Chrome finish

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Later 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.