Discovery 2. Manual — part 428

ENGINE - V8

DESCRIPTION AND OPERATION

12-2-5

1 Core plugs
2 Cylinder block
3 Camshaft
4 Dipstick tube, clamp and bolt
5 Woodruff key
6 Timing chain
7 Camshaft timing gear
8 Washer
9 Bolt - camshaft timing gear

10 Thrust plate - camshaft end-float
11 Bolt - camshaft thrust plate
12 Gasket - timing cover
13 Timing cover
14 Oil pressure switch
15 Bolt
16 Crankshaft front oil seal
17 Oil filter element
18 Crankshaft front pulley
19 Washer
20 Bolt - crankshaft front pulley
21 Upper main bearing shell
22 Upper centre main bearing shell and thrust

washer

23 Crankshaft
24 Woodruff key
25 Crankshaft timing gear
26 Lower main bearing shells
27 Numbers 1, 2 and 3 main bearing caps
28 Bolt - main bearing caps
29 Oil pick-up pipe and strainer
30 'O' ring

31 Bolt - oil pick-up pipe
32 Gasket - sump
33 Sump
34 Bolt - sump
35 Sump oil drain plug
36 Sealing washer
37 Spacer, washers and nut - oil pick-up pipe
38 Number 4 main bearing cap
39 Bolt - connecting rod big-end bearing cap
40 Connecting rod big-end bearing shell - lower
41 Connecting rod big-end bearing cap
42 Number 5 - rear main bearing cap
43 Cruciform seal - rear main bearing cap
44 Number 5 - rear main bearing shell
45 Crankshaft rear oil seal
46 Crankshaft knock sensor
47 Side bolt - main bearing cap
48 Side Allen bolt - main bearing cap
49 Dowty washers
50 Connecting rod big-end bearing shell - upper
51 Connecting rod
52 Piston
53 Gudgeon pin
54 Oil control ring
55 Top compression ring
56 2nd compression ring
57 Flywheel/drive plate and starter ring gear
58 Bolt - flywheel/drive plate

ENGINE - V8

12-2-6

DESCRIPTION AND OPERATION

Description

General
The V8 petrol engine is an eight cylinder, water cooled unit having two banks of four cylinders positioned at 90 degrees
to each other. The engine comprises five main castings - two cylinder heads, cylinder block, timing cover and the oil
sump, all of which are manufactured from aluminium alloy.

NAS market vehicles from 03 model year receive a 4.6 litre version of the V8 engine to replace the previous 4.0 litre
version.

Cylinder heads
The cylinder heads are fitted with replaceable valve guides and valve seat inserts with the combustion chambers
formed in the head. Each cylinder head is sealed to the cylinder block with a gasket. The exhaust manifolds are bolted
to the outside of each cylinder head whilst the inlet manifolds are located in the centre of the 'Vee' and are bolted to
the inside face of each head. Inlet and exhaust manifolds are sealed to the cylinder heads by means of gaskets.

Each cylinder has a single inlet and exhaust valve. The exhaust valves are of the 'carbon break' type, a recess on the
valve stem prevents a build-up of carbon in the valve guide by dislodging particles of carbon as the valve stem moves
up and down the guide. Inlet and exhaust valve stem oil seals are fitted at the top of each valve guide. Valve operation
is by means of rocker arms, push rods and hydraulic tappets. Each of the rocker arms is located on a rocker shaft
which is supported by means of pedestals bolted to the cylinder heads. A spring, positioned on either side of each
rocker arm, maintains the correct relative position of the arm to its valve stem. The rocker arms are operated directly
by the push rods which pass through drillings in the cylinder heads and cylinder block. The bottom end of each push
rod locates in a hydraulic tappet operated by the single, chain driven camshaft.

The rocker covers are bolted to the cylinder heads and are sealed to the heads by a rubber gasket. Stub pipes for
crankcase ventilation hose connections are fitted to each rocker cover, the pipe in the right hand cover incorporates
an oil separator. The engine oil filler cap is situated in the right hand cover.

Cylinder block and camshaft
The cylinder block is fitted with cast iron cylinder liners which are shrink fitted and locate on stops in the block. The
camshaft is positioned in the centre of the cylinder block and runs in one piece bearing shells which are line bored
after fitting. Camshaft end-float is controlled by a thrust plate bolted to the front of the cylinder block. A timing gear,
chain driven by the crankshaft timing gear is bolted to the front of the camshaft.

Crankshaft and main bearings
The crankshaft is carried in five main bearings. The upper main bearing shell locations are an integral part of the
cylinder block casting. The lower main bearing caps are bolted to the cylinder block on either side of the upper bearing
shell locations with an additional bolt being inserted into each cap from either side of the cylinder block. The rear
main bearing cap carries the crankshaft rear oil seal and is sealed to the cylinder block by means of cruciform shaped
seals in each side of the cap. Number four main bearing cap carries the stud fixing for the oil pick-up pipe. Lower
main bearing shells are plain whilst the upper shells have an oil feed hole and are grooved. Crankshaft end-float is
controlled by the thrust faces of the upper centre shell. The crankshaft timing gear is located on the front of the
crankshaft by means of a Woodruff key which is also used to drive the gear type oil pump. The flywheel/drive plate
carries the crankshaft position sensor reluctor ring and is dowel located and bolted to the flywheel.

Timing cover
The timing cover is bolted to the front of the cylinder block and is sealed to the block with a gasket. The disposable,
full flow oil filter canister is screwed on to the timing cover which also carries the oil pressure switch, oil pressure relief
valve and crankshaft front oil seal. The gear type oil pump is integral with the cover which also has an internal oilway
to direct oil from the oil cooler to the filter.

NOTE: Oil coolers are only fitted to vehicles up to VIN 756821.

ENGINE - V8

DESCRIPTION AND OPERATION

12-2-7

Oil sump
The oil sump is bolted to the bottom of the cylinder block and the timing cover and is sealed to both components with
a one piece gasket. A removable baffle to prevent oil surge is fitted in the sump. The oil pick-up pipe and strainer
assembly is positioned within the sump and is attached at the pick-up end to a stud screwed into number four main
bearing cap and at the delivery end to the oil pump. The oil drain plug is located in the bottom of the sump and is
sealed with a washer.

Pistons and connecting rods
Each of the aluminium alloy pistons has two compression rings and an oil control ring. The pistons are secured to the
connecting rods by semi-floating gudgeon pins. Each gudgeon pin is offset by 0.5 mm (0.02 in). The top of each piston
is recessed, the depth of recess determining the compression ratio of the engine. Plain, big-end bearing shells are
fitted to each connecting rod and cap.

ENGINE - V8

12-2-8

DESCRIPTION AND OPERATION

Lubrication

A - To oil cooler, B - From oil cooler

NOTE: The oil cooler is only fitted to vehicles up to VIN 756821.

1 Rocker shaft assembly
2 Hydraulic tappet
3 Oil pump
4 Oil filter element
5 Oil pick-up pipe and strainer
6 Oil pressure switch

Oil is drawn from the sump through a strainer and into the oil pump via the oil pick-up pipe. Pressurised oil from the
pump passes through the oil cooler (if fitted) mounted in front of the radiator and returns to the full flow oil filter