Defender. Manual — part 77
Item
Part Number
Description
1
-
Oil pick-up pipe
2
-
Bolt (2 off)
The fabricated steel oil pick-up is immersed in the oil reservoir to provide a supply to the oil pump during all normal
vehicle attitudes. A mesh screen in the inlet prevents debris from entering the oil system.
Oil Pump
Item
Part Number
Description
1
-
Ladder frame
2
-
Bolt (4 off)
3
-
Oil pump
4
-
Cylinder block
5
-
Oil pump drive chain
The oil pump is located on the LH front underside of the ladder frame and is secured by 4 bolts. The unit is driven by a
drive chain, via the crankshaft sprocket, and receives its oil feed from the main gallery via drillings in the cylinder block.
The chain is tensioned and guided by means of a hydraulic chain tensioner.
Oil Filter and Cooler Assembly
Item
Part Number
Description
1
-
Bolt (2 off)
2
-
Engine oil cooler
3
-
Oil filter housing
4
-
Oil filter drain plug
5
-
Oil filter and cooler assembly seal
6
-
Bolt (4 off)
7
-
Oil pressure switch
The engine is lubricated by a forced feed oil circulation system with a oil filter and oil cooler assembly.
The oil filter and oil cooler assembly is attached to the LH side of the ladder frame and consists a full-flow, disposable
canister-type filter, oil cooler and oil pressure switch. The mounting plate aligns with the oil gallery in the ladder frame
and is sealed by an 'O' ring.
The engine cooling system cools the oil in the oil cooler and is regulated by means of a separate thermostat, which
prevents the flow of coolant through the oil cooler when the engine is cold, ensuring the engine oil warms up quickly.
The thermostat opens at 75±2°C (167±35°F).
Oil is delivered to and from the oil cooler through galleries in the cylinder block. Hoses from the engine cooling system
are connected to 2 pipes on the oil cooler for the supply and return of coolant.
Lubrication System Operation
Oil is drawn, via a strainer and pick-up pipe in the sump into oil pump, which has an integral pressure relief valve. The
strainer in the pick-up pipe prevents any ingress of foreign particles from passing through to the inlet side of the oil
pump and damaging the oil pump and restricting oil drillings. The oil pressure relief valve in the oil pump opens if the oil
pressure becomes excessive and diverts oil back around the pump.
The lubrication system is designed so that a higher proportion of oil flow is directed to the cylinder block main oil gallery
while a lower proportion of oil flow, (controlled by a restrictor in the oil filter housing), is directed to the engine oil
cooler. The remainder of the oil flow from the outlet side of the oil filter is combined with the return flow from the oil
cooler before being passed into the cylinder block main oil gallery.
The main oil gallery has drillings that direct the oil to the cylinder head and the main bearings. Cross drillings in the
crankshaft main bearings carry the oil to the connecting rod big-end bearings. Oil galleries in the cylinder head carry the
oil to the camshafts and the hydraulic lash adjusters.
The oil pressure switch is located in the oil filter and oil cooler mounting plate to sense the oil pressure level before the
oil flow enters the main gallery in the cylinder block. A warning lamp in the instrument cluster is illuminated if low oil
pressure is detected.
Oil at reduced pressure is directed towards the cylinder head via a restrictor in the cylinder block/cylinder head locating
dowel. Oil then passes through a drilling in the cylinder head to the camshaft carrier, where it is directed via separate
galleries to the camshaft bearings and hydraulic tappet housings. Return oil from the cylinder head drains into the sump
via the cylinder head bolt passages.
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