water pump LAND ROVER DEFENDER 1996 User Guide

26COOLING SYSTEM
2
DESCRIPTION AND OPERATION ENGINE (COOLANT) COOLING
Description
The 300Tdi engine uses a pressurised cooling system
and cross flow radiator which is supplied with coolant
from an expansion tank mounted on the RH side of
the engine compartment. A belt driven centrifugal
water pump, fitted to an auxiliary mounting assembly,pumps coolant to the engine crankcase, cylinder head
and vehicle heater unit.
An eleven bladed fan, incorporating a viscous
coupling, is driven by an independent pulley secured
to the front cover plate. The thermostat housing,
bolted to the front of the cylinder head, is fitted with a
vent valve that purges excessive air pressure and
coolant back to the expansion tank.
Engine coolant circulation (engine warm - thermostat open).
1.Radiator
2.Thermostat/housing
3.Radiator bottom hose
4.Viscous fan
5.Water pump
6.Radiator top hose
7.Heater return hose
8.Coolant supply hose9.By-pass hose
10.Radiator bleed (purge) hose
11.Thermostat housing bleed (purge) hose
12.'Y' piece ejector
13.Expansion tank
14.Heater rail
15.Heater unit
16.Heater feed hose

COOLING SYSTEM
3
DESCRIPTION AND OPERATION COOLANT CIRCULATION
Operation
When the engine is started from cold the thermostat
(2) prevents coolant circulation through the radiator by
closing off the top hose (6). During the engine warm
up period the water pump (5) circulates coolant to the
cylinders in the crankcase and through separate ports
to the cylinder head. At the rear of the cylinder head a
proportion of the flow is diverted through a heater feed
pipe (16) to the matrix of the heater unit (15). The
coolant is then carried, via a heater return rail (14) and
hoses (7), back to the water pump. The remaining
coolant flows through a by-pass hose (9) at the
thermostat housing and back to the water pump to
complete the first cycle.
When the normal engine running temperature is
reached, the thermostat opens, closing off the by-pass
hose (9). Coolant is then circulated via the top hose
(6) and through the radiator, where it is cooled and
drawn from the radiator bottom hose (3) by the water
pump (5). The coolant circulation through the
crankcase and cylinder head remains the same.
Two bleed pipes (10) and (11) help control the system
pressure by purging excess air and coolant to the
expansion tank via the 'Y'piece ejector (12).VISCOUS FAN
Description
The viscous drive unit for the engine cooling fan,
provides a means of controlling the speed of the fan
relative to the running temperature of the engine. The
viscous unit is a type of fluid coupling, which drives
the fan blades by means of 'silicone fluid'.
1.Input (drive) member
2.Output (driven) member
3.Sensing mechanism (bi-metal coil)
The fan drive has to be engaged only periodically,
between 5% and 10%, during normal operating
conditions, because the engine is cooled by ram air
for most of the time.

COOLING SYSTEM
3
REPAIR WATER PUMP
Service repair no - 26.50.01
Remove
1.Disconnect battery.
2.Drain cooling system.
See Adjustment, Drain
and refill cooling system
3.Remove radiator top hose.
4.Remove intercooler top hose.
5.Slacken water pump and power steering pump
pulley retaining bolts.
6.Remove drive belt.
See ELECTRICAL, Repair,
Auxiliary drive belt
7.Unscrew flange nut and remove belt tensioner.
8.Remove oil filler cap and remove rocker cover
insulation.
9.Slacken retaining clip and disconnect hose at
heater rail.
10.Unscrew 3 bolts and remove water pump pulley.
11.Unscrew 3 bolts and remove power steering
pump pulley.
12.Remove 8 bolts securing water pump, noting
location of 3 through bolts into cylinder block.
13.Withdraw pump and gasket from auxiliary
mounting bracket.
14.Clean all gasket material from mating faces.
Refit
15.Using new gasket, fit water pump to mounting
bracket. Tighten bolts to
25 Nm (18 lbf/ft).
16.Fit power steering pump pulley.
17.Fit water pump pulley. Tighten bolts of both
pulleys to
25 Nm (18 lbf/ft).
18.Fit drive belt.See ELECTRICAL, Repair,
Auxiliary drive belt
19.Fit hose at heater rail.
20.Fit rocker cover insulation and oil filler cap.
21.Fit drive belt tensioner. Tighten retaining nut to
45 Nm (33 lbf/ft).
22.Fit intercooler top hose.
23.Fit radiator top hose.
24.Refill cooling system.
See Adjustment, Drain
and refill cooling system
25.Reconnect battery.

26COOLING SYSTEM
4
REPAIRREV: 05/99 AUXILIARY MOUNTING BRACKET AND GASKET
Service repair no - 26.50.04
Remove
1.Disconnect battery.
2.Drain cooling system
See Adjustment, Drain
and refill cooling system
.
3.Remove radiator top hose.
4.Remove intercooler top hose.
5.Remove viscous fan unit.
See Viscous
coupling and fan
6.Remove fan cowl.See Fan cowl
7.Slacken power steering pump pulley retaining
bolts.
8.Remove drive belt.
See ELECTRICAL, Repair,
Auxiliary Drive belt
9.Unscrew 3 bolts and remove power steering
pump pulley.
10.Remove 4 bolts securing power steering pump
mounting bracket.
11.Lower pump and bracket. Do not disconnect fluid
pipes.
12.Remove generator.
See ELECTRICAL, Repair,
Generator
13.Unscrew retaining nut and remove drive belt
tensioner.
14.Release hose clip from bracket above water
pump.15.Disconnect bottom hose/heater return hose at
water pump and heater rail.
16.Disconnect by-pass hose from water pump and
thermostat housing.
17.Remove 5 bolts (one with nut) and single
retaining nut, securing auxiliary mounting
bracket to cylinder block.
18.Withdraw mounting bracket, complete with water
pump.
19.Remove gasket and clean mating faces.
Refit
20.Using 2 slave studs, fit new gasket.
NOTE: All fixing bolts and nuts should be
tightened to
25 Nm (18 lbf/ft)unless
otherwise stated.
21.Locate mounting bracket, complete with water
pump on slave studs and secure with 4 other
fixings.
22.Remove slave studs and fit remaining bolts/nuts.
23.Fit by-pass hose to thermostat housing and
water pump.
24.Fit bottom hose/heater return hose to water
pump and heater rail.
25.Fit heater hose clip to mounting bracket.
26.Fit drive belt tensioner. Tighten nut to
45 Nm (33
lbf/ft).
27.Fit generator.See ELECTRICAL, Repair,
Generator
Do not fit drive belt at this stage.

COOLING SYSTEM
5
REPAIR 28.Secure steering pump and bracket to auxiliary
mounting bracket.
29.Fit steering pump pulley.
30.Fit drive belt
See ELECTRICAL, Repair,
Auxiliary drive belt
.
31.Fit fan cowl
See Fan cowl.
32.Fit viscous fan unit
See Viscous coupling and
fan
.
33.Fit intercooler top hose.
34.Fit radiator top hose.
35.Refill cooling system.
See Adjustment, Drain
and refill cooling system
36.Reconnect battery.THERMOSTAT
Service repair no - 26.45.01
Remove
1.Partially drain cooling system, until coolant level
is below thermostat housing.
2.Disconnect top hose from outlet elbow.
3.Disconnect electrical connections to water
temperature switch.
4.Unscrew 2 bolts and remove outlet elbow.
5.Withdraw thermostat. Note 88°C rating of
thermostat.
6.Place thermostat in a container half full of water.
Heat water and observe temperature at which
thermostat begins to open. Thermostat is
satisfactory if it opens between 85°-89°C.
Refit
7.Fit thermostat with jiggle pin/vent hole upwards.
8.Secure outlet elbow to thermostat housing.
Tighten bolts to
25 Nm (18 lbf/ft).
9.Fit water temperature switch connections.
10.Fit top hose to outlet elbow.
11.Refill cooling system.
See Adjustment, Drain
and refill cooling system

MANUAL GEARBOX
1
DESCRIPTION AND OPERATION R380 GEARBOX
Description
The all synchromesh five speed manual gearbox unit,
is married to a two speed transfer gearbox.
All the gears, including reverse, run on needle roller
bearings and the main, layshaft and primary shafts
are supported by tapered roller bearings.The whole of the geartrain is lubricated through
drillings in the shafts, supplied by a low pressure
pump driven from the rear of the layshaft. The gear
change has a single rail selector and spool type
interlock. The main and transfer gearboxes ventilate
through nylon pipes, which terminate high up in the
engine compartment to prevent water entry when the
vehicle is operating in adverse conditions.
R380 Gearbox Components
1.Mainshaft 1st gear
2.Mainshaft 2nd gear
3.Mainshaft 3rd gear
4.Primary input shaft/4th gear
5.Mainshaft 5th gear
6.Layshaft
7.Mainshaft
8.Lubrication pump
9.Oil filter10.Ventilation pipe
11.Single rail gear shift
12.1st/2nd synchromesh
13.Oil seals
14.3rd/4th synchromesh
15.5th/reverse gear synchromesh
16.Selective spacers (mainshaft/layshaft end float)
17.Selective spacer (5th gear/reverse hub)

57STEERING
6
REPAIR POWER STEERING SYSTEM - BLEED
Service repair no - 57.15.02
1.Check that fluid level is at maximum level
See
MAINTENANCE , Under bonnet maintenance.
2.Run engine to normal operating temperature.
3.Recheck reservoir fluid level, top up if necessary
NOTE: During operations 4 to 6, maintain
maximum fluid level in reservoir. Do not
increase engine speed or move steering
wheel.
4.With engine at idle speed, slacken bleed screw.
When fluid seeps past bleed screw retighten
screw.
5.Check fluid level.
6.Clean away fluid around bleed screw.
7.Check hose connections, pump and steering box
for fluid leaks by holding steering on full lock in
both directions.
CAUTION: Do not maintain this pressure
for more than 30 seconds in any one
minute to avoid overheating fluid and
possibly damaging seals.
8.Carry out road test.POWER STEERING FLUID RESERVOIR
Service repair no - 57.15.08
Remove
1.Position drain tin beneath reservoir.
2.Slacken mounting bracket clamp bolt and raise
reservoir to gain access to feed and return hose
retaining clips.
3.Slacken clips, disconnect hoses from reservoir,
allow fluid to drain.
4.Remove reservoir.
CAUTION: Plug connections to prevent
ingress of dirt.
CAUTION: Discard fluid drained from
system. Do not allow fluid to contact
paintwork, if spilled, remove fluid and
clean area with warm water.
Refit
5.Position reservoir, connect feed and return
hoses and tighten clips to
3 Nm (2 lbf/ft).
6.Fit reservoir in clamp, tighten clamp bolt.
7.Fill reservoir between upper mark and end of
dipstick with power steering fluid
See
MAINTENANCE , Under bonnet maintenance
.
8.Bleed power steering system
See Power
steering system - bleed
.