Defender (1993+). Instruction - page 16

ENGINE

RR3524M

34. Cylinder heads (2)

46. Plenum chamber upper

35. Rocker covers (2)

47, Air filter

36. Oil separator

48. Oil filler

37. Rocker shafts (2)

49. Thermostat

38. Hydraulic tappets (8)

50. Thermostat cover

39. Pushrods (8)

51. Inlet valve spring, cap, seal

and

collets

(8)

40. Rocker brackets (8)

52. Exhaust valve spring, cap, collets

(8)

41. Rocker arms (4) left and

(4)

right

53. Inlet valve and seat (8)

42. Rocker shaft springs (6)

54. Exhaust valve and seat (8)

43. Inlet manifold

55. Tappet cover gasket and seals

44.

Plenum chamber lower

56. Cylinder head gaskets (2)

45. Ram pipes (8)

57. Valve guides (16)

ENGINE

Lubrication

system

The

V8

full flow lubrication system uses an external gear pump which

is driven from the front of the camshaft

via the distributor drive shaft. The oil pump gears are housed in the timing cover and the pressure relief valve,
warning light switch and filter are

fitted

to the gear cover.

Oil drawn through the centrally located steel gauze strainer in the sump, is pumped under pressure through oil
cooler located

in the lower half of the main coolant radiator. The cooled oil then passes through the filter,

before being distributed from the main gallery via drillings, to the various components in the engine.

Lubrication to

the

thrust side of the cylinders

is

by

oil

grooves machined in each connecting rod big end joint

face, which are timed to align with holes in the big end journals on the Dower and exhaust strokes.

Lubrication system

1

Oil to cooler

2

Oil from cooler

ENGINE

RR3528M

Distributor/oil pump drive and timing chain
lubrication

The distributor/oil pump drive, and timing chain
lubricated from the camshaft front bearing. The feed

to

the timing chain is channelled along the camshaft

sprocket, key and spacer where

it

sprays onto the

chain.

Unfiltered oil

Any blockage of the filter element will open the
by-pass valve and maintain an un-filtered

oil

supply

RR3526M

to

the bearings.

1

Bearing

2

Camshaft

3

Key

4

Cam

gear

5 Spacer

6

Distributor oil pump drive gear

Filtered oil

Lubrication pressure is controlled by the pressure
relief valve

E which allows excess pressure to

escape into the pump suction gallery D. The oil is
then pumped through the cooler via connections A
and

B before passing through the anti-siphon valve

and into the filter. Filtered oil

is

supplied to the

engine bearings by port

C.

F

RR3529M

ENGINE

Hydraulic tappets

As the tappet assembly moves

off

the peak of the

cam

to

the closing side, the ball valve

2

opens

to

The purpose

of the hydraulic tappet is

to

provide

equalize the pressure in both chambers which

maintenance

free and quiet operation of the inlet and

ensures that the cylinder valve fully closes when the

exhaust valves. It achieves its designed purpose by

tappet

is on the back of the cam.

utilizing engine oil pressures to eliminate the
mechanical clearance between the rockers and the
valve stems.

Operation

During normal operation, engine oil pressure present
in the upper chamber

1,

passes through the

non-return ball valve

2

and into the lower (high

pressure) chamber 3.

When the cam begins

to

lift

the outer sleeve

4,

the

resistance

of the cylinder valve spring felt through

the push rod and seat 5, causes the inner sleeve

6,

to move downwards inside the outer. This slight
downward movement

of the inner sleeve

6,

closes

the ball valve

2

and increases the hydraulic pressure

in the high pressure chamber 3

,

sufficient

to ensure

that the push rod opens the cylinder valve fully.

RR3531M

1

Upperchamber

2 Non-return ball valve

3

Lower chamber (high pressure)

4

Outer sleeve

5 Pushrod seat

6

Inner sleeve

7

Spring

8

Clip

6

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