Ford Mondeo (petrol engines). Manual - part 23

4 If a hose proves stubborn, try to release it
by rotating it on its unions before attempting
to work it off. Gently prise the end of the hose
with a blunt instrument (such as a flat-bladed
screwdriver), but do not apply too much force,
and take care not to damage the pipe stubs or
hoses. Note in particular that the radiator hose
unions are fragile; do not use excessive force
when attempting to remove the hoses. If all
else fails, cut the hose with a sharp knife, then
slit it so that it can be peeled off in two pieces.
While expensive, this is preferable to buying a
new radiator. Check first, however, that a new
hose is readily available.
5 When refitting a hose, first slide the clamps

onto the hose, then work the hose onto its
unions. If the hose is stiff, use soap (or
washing-up liquid) as a lubricant, or soften it
by soaking it in boiling water, but take care to
prevent scalding.
6 Work each hose end fully onto its union,
then check that the hose is settled correctly
and is properly routed. Slide each clip along
the hose until it is behind the union flared end,
before tightening it securely.
7 Refill the system with coolant (see Chap-
ter 1).
8 Check carefully for leaks as soon as
possible after disturbing any part of the
cooling system.

Note: Refer to the warnings given in Section 1
of this Chapter before starting work.

Removal

1 Disconnect the battery negative (earth) lead
(see Chapter 5, Section 1).
2 Unbolt the resonator support bracket from
the engine compartment front crossmember.
Slacken the two clamp screws securing the
resonator to the air mass meter and plenum
chamber hoses, then swing the resonator up
clear of the thermostat housing (see Chap-
ter 4).
3 Drain the cooling system (see Chapter 1). If
the coolant is relatively new or in good
condition, drain it into a clean container and
re-use it.
4 Disconnect the expansion tank coolant
hose and the radiator top hose from the
thermostat housing’s water outlet.
5 Unbolt the water outlet and withdraw the
thermostat  (see illustration). Note the
position of the air bleed valve, and how the
thermostat is installed (which end is facing
outwards).

Testing

General check

6 Before assuming the thermostat is to blame
for a cooling system problem, check the
coolant level, auxiliary drivebelt tension and
condition (see Chapter 1) and temperature
gauge operation.
7 If the engine seems to be taking a long time
to warm up (based on heater output or
temperature gauge operation), the thermostat
is probably stuck open. Renew the
thermostat.
8 If the engine runs hot, use your hand to
check the temperature of the radiator top
hose. If the hose isn’t hot, but the engine is,
the thermostat is probably stuck closed,
preventing the coolant inside the engine from
escaping to the radiator - renew the
thermostat. 

4 Thermostat - 

removal, testing and refitting

Cooling, heating and air conditioning systems  3•3

3

4.5  Unbolt water outlet to withdraw

thermostat

3.1  Cooling system components

1  Radiator
2  (Twin) electric cooling fan 

and shroud

3  Expansion tank
4  Filler/pressure cap
5  Bolt
6  (Single) electric cooling fan 

and shroud

7  Bolt
8  Coolant pipe
9  Nut

10  Top mounting rubber
11  Bottom mounting rubber
12  Bolt
13  Radiator mounting 

bracket

14  Coolant hose
15  Bolt
16  Radiator top hose
17  Coolant pipe/hose
18  Stud
19  Thermostat housing
20  Radiator bottom hose

Caution: Don’t drive the vehicle
without a thermostat. The lack of
a thermostat will slow warm-up

time. The engine management system’s
ECU will then stay in warm-up mode for
longer than necessary, causing emissions
and fuel economy to suffer.

9 If the radiator top hose is hot, it means that
the coolant is flowing and the thermostat is
open. Consult the “Fault diagnosis” section at
the front of this manual to assist in tracing
possible cooling system faults.

Thermostat test

10 If the thermostat remains in the open
position at room temperature, it is faulty, and
must be renewed as a matter of course.
11 To test it fully, suspend the (closed)
thermostat on a length of string in a container
of cold water, with a thermometer beside it;
ensure that neither touches the side of the
container.
12 Heat the water, and check the
temperature at which the thermostat begins to
open; compare this value with that specified.
Continue to heat the water until the
thermostat is fully open; the temperature at
which this should happen is stamped in the
unit’s end. Remove the thermostat and allow
it to cool down; check that it closes fully.
13 If the thermostat does not open and close
as described, if it sticks in either position, or if
it does not open at the specified temperature,
it must be renewed.

Refitting

14 Refitting is the reverse of the removal
procedure. Clean the mating surfaces
carefully, renew the thermostat’s sealing ring
if it is worn or damaged, then refit the
thermostat with its air bleed valve uppermost
(see illustration). Tighten the water outlet
bolts to the specified torque wrench setting.
15 Refill the cooling system (see Chapter 1).
16 Start the engine and allow it to reach
normal operating temperature, then check for
leaks and proper thermostat operation.

Note: Refer to the warnings given in Section 1
of this Chapter before starting work.

Testing

1 The radiator cooling fan is controlled by the
engine management system’s ECU, acting on
the information received from the coolant
temperature sensor. Where twin fans or two-
speed fans are fitted, control is through a
resistor assembly, secured to the bottom left-
hand corner of the fan shroud - this can be
renewed separately if faulty.
2 First, check the relevant fuses and relays
(see Chapter 12).
3 To test the fan motor, unplug the electrical
connector, and use fused jumper wires to
connect the fan directly to the battery. If the
fan still does not work, renew the motor.
4 If the motor proved sound, the fault lies in
the coolant temperature sensor (see Section 6
for testing details), in the wiring loom (see
Chapter 12 for testing details) or in the engine
management system (see Chapter 6).

Removal and refitting

5 Disconnect the battery negative (earth) lead
(see Chapter 5, Section 1).
6 Unbolt the resonator support bracket from
the engine compartment front crossmember.
Slacken the two clamp screws securing the
resonator to the air mass meter and plenum
chamber hoses, then swing the resonator up
clear of the thermostat housing (see Chapter 4).

7 Drain the cooling system (see Chapter 1).
8 Remove the radiator top hose completely.
Disconnect the metal coolant pipe/hose from
the thermostat, and unbolt the coolant pipe
from the exhaust manifold heat shield.
9 Unplug the cooling fan electrical
connector(s), then release all wiring and hoses
from the fan shroud.
10 Unscrew the two nuts securing the fan
shroud, then lift the assembly to disengage it
from its bottom mountings and from the
radiator top edge (see illustrations).
11 Withdraw the fan and shroud as an
assembly (see illustration).
12 At the time of writing, the fan, motor and
shroud are available only as a complete
assembly, and must be renewed together if
faulty.
13 Refitting is the reverse of the removal
procedure. Ensure that the shroud is settled
correctly at all four mounting points before
refitting and tightening the nuts.

Note: Refer to the warnings given in Section 1
of this Chapter before starting work.

Coolant temperature gauge
sender

Testing

1 If the coolant temperature gauge is inopera-
tive, check the fuses first (see Chapter 12).
2 If the gauge indicates Hot at any time,
consult the “Fault finding” section at the end
of this manual, to assist in tracing possible
cooling system faults.
3 If the gauge indicates Hot shortly after the
engine is started from cold, unplug the
coolant temperature sender’s electrical
connector. If the gauge reading now drops,
renew the sender. If the reading remains high,
the wire to the gauge may be shorted to earth,
or the gauge is faulty.
4 If the gauge fails to indicate after the engine
has been warmed up (approximately 
10 minutes) and the fuses are known to be
sound, switch off the engine. Unplug the

6 Cooling system electrical

switches and sensors - 
testing, removal and refitting

5 Radiator electric cooling 

fan(s) - testing, 
removal and refitting

3•4 Cooling, heating and air conditioning systems

4.14  Ensure thermostat is refitted as

shown

5.10A  Fan shroud is secured at top by

mounting nut (A), at bottom by clip (B) . . .

5.10B  . . . and is hooked over radiator top

edge (one point arrowed)

5.11  Removing radiator electric cooling

fan and shroud assembly

sender’s electrical connector, and use a
jumper wire to connect the white/red wire to a
clean earth point (bare metal) on the engine.
Switch on the ignition without starting the
engine. If the gauge now indicates Hot, renew
the sender.
5 If the gauge still does not work, the circuit
may be open, or the gauge may be faulty. See
Chapter 12 for additional information.

Removal

6 Unbolt the resonator support bracket from
the engine compartment front crossmember.
Slacken the two clamp screws securing the
resonator to the air mass meter and plenum
chamber hoses, then swing the resonator up
clear of the thermostat housing (see Chap-
ter 4).
7 Drain the cooling system (see Chapter 1).
8 Disconnect the expansion tank coolant
hose and the radiator top hose from the
thermostat housing’s water outlet, then
disconnect the metal coolant pipe/hose from
the thermostat.
9 Unplug the electrical connector from the
sender (see illustration).
10 Unscrew the sender and withdraw it.

Refitting

11 Clean as thoroughly as possible the
opening in the thermostat housing, then apply
a light coat of sealant to the sender’s threads.
Screw in the sender and tighten it to the
specified torque wrench setting, and plug in
its electrical connector.
12 Reconnect the hoses and refit the
resonator, top-up the cooling system (see
Chapter 1) and run the engine. Check for
leaks and proper gauge operation.

Coolant temperature sensor

Testing

13 Disconnect the battery negative (earth)
lead (see Chapter 5, Section 1).
14 Unbolt the resonator support bracket
from the engine compartment front
crossmember. Slacken the two clamp screws
securing the resonator to the air mass meter
and plenum chamber hoses, then swing the
resonator up clear of the thermostat housing
(see Chapter 4).
15 Unplug the electrical connector from the
sensor (see illustration).
16 Using an ohmmeter, measure the
resistance between the sensor terminals.
Depending on the temperature of the sensor
tip, the resistance measured will vary, but
should be within the broad limits given in the
Specifications Section of this Chapter. If the
sensor’s temperature is varied - by removing
it (see below) and placing it in a freezer for a
while, or by warming it gently - its resistance
should alter accordingly.
17 If the results obtained show the sensor to
be faulty, renew it.
18 On completion, plug in the connector and
refit the resonator.

Removal

19 Disconnect the battery negative (earth)
lead (see Chapter 5, Section 1).
20 Unbolt the resonator support bracket
from the engine compartment front
crossmember. Slacken the two clamp screws
securing the resonator to the air mass meter
and plenum chamber hoses, then swing the
resonator up clear of the thermostat housing
(see Chapter 4).
21 With the engine completely cool, remove
the expansion tank filler cap to release any
pressure, then refit the cap. Provided you
work swiftly and plug the opening as soon as
the sensor is unscrewed, coolant loss will thus
be minimised; this will avoid the draining of
the complete cooling system which would
otherwise be necessary (see Chapter 1).
22 Unplug the electrical connector from the
sensor.
23 Unscrew the sensor and withdraw it. If the
cooling system has not been drained, plug the
opening as quickly as possible.

Refitting

24 Clean as thoroughly as possible the
opening in the thermostat housing, then apply
a light coat of sealant to the sensor’s threads.
Remove the material used to plug the sensor
hole (where applicable), and quickly install the
sensor to prevent coolant loss. Tighten the
sensor to the specified torque wrench setting,
and plug in its electrical connector.
25 Refit the resonator, top-up the cooling
system (see Chapter 1) and run the engine,
checking for leaks.

Coolant low level switch

Testing

26 The switch is a reed-type unit mounted in
the bottom of the cooling system expansion
tank, activated by a magnetic float. If the
coolant level falls to the “MIN” level or less,
the appropriate bulb lights in the warning
display.
27 If the bulb fails to light during the 5-
second bulb test, check the bulb, and renew if
necessary as described in Chapter 12.
28 To check the switch itself, unplug its
electrical connector, and use an ohmmeter to
measure the resistance across the switch

terminals. With the float up, a resistance of 
90 ohms should be measured; when it is
down, the resistance should increase to
approximately 150 kilohms.
29 If the results obtained from the check are
significantly different from those expected,
the switch is faulty, and must be renewed.
30 If the switch and bulb are proven to be
sound, the fault must be in the wiring or in the
auxiliary warning control assembly (see
Chapter 12).

Removal

31 Disconnect the battery negative (earth)
lead (see Chapter 5, Section 1).
32 Remove the expansion tank (see Sec-
tion 7).
33 Unplug the switch electrical connector.
34 Release the switch by twisting its retainer
anti-clockwise, then withdraw it.

Refitting

35 Refitting is the reverse of the removal
procedure. Refill the cooling system (see
Chapter 1). Start the engine, and check for
coolant leaks when it is fully warmed-up.

Note: Refer to the warnings given in Section 1
of this Chapter before starting work.

Radiator

Removal

Note: If leakage is the reason for removing the
radiator, bear in mind that minor leaks can
often be cured using a radiator sealant with
the radiator in situ.
1 Remove the radiator fan and shroud
assembly (see Section 5).
2 Disconnect the bottom hose from the
radiator.
3 If the vehicle has automatic transmission,
disconnect the fluid cooler lines, and plug the
lines and fittings.
4 If the vehicle has air conditioning, unscrew
the condenser mounting nuts or bolts, detach
the condenser from the radiator, and tie it to
the engine compartment front crossmember. 

7 Radiator and expansion tank -

removal, inspection and refitting

Cooling, heating and air conditioning systems  3•5

3

6.9  Location (arrowed) of coolant

temperature gauge sender

6.15  Location (arrowed) of coolant

temperature sensor

Warning: Do not disconnect any
of the refrigerant hoses.

5 Unbolt the radiator mounting brackets from
the subframe; note that they are handed, and
are marked to ensure correct refitting (see
illustration). Collect the bottom mounting
rubbers, noting which way up they are fitted,
and store them carefully.
6 Carefully lower the radiator from the
vehicle, and withdraw it.
7 With the radiator removed, it can be
inspected for leaks and damage. If it needs
repair, have a radiator specialist or dealer
service department perform the work, as
special techniques are required.
8 Insects and dirt can be removed from the
radiator with a garden hose or a soft brush.
Don’t bend the cooling fins as this is done.

Refitting

9 Refitting is the reverse of the removal
procedure. Be sure the mounting rubbers are
seated properly at the base of the radiator.
10 After refitting, refill the cooling system
with the proper mixture of antifreeze and
water (see Chapter 1).
11 Start the engine, and check for leaks.
Allow the engine to reach normal operating
temperature, indicated by the radiator top
hose becoming hot. Recheck the coolant
level, and add more if required.

12 If working on an vehicle with automatic
transmission, check and add transmission
fluid as needed (see Chapter 1).

Expansion tank

13 With the engine completely cool, remove
the expansion tank filler cap to release any
pressure, then refit the cap.
14 Disconnect the hoses from the tank,
upper hose first. As each hose is
disconnected, drain the tank’s contents into a
clean container. If the antifreeze is not due for
renewal, the drained coolant may be re-used,
if it is kept clean.
15 Unscrew the tank’s two mounting bolts
and withdraw it, unplugging the coolant low
level switch electrical connector (where fitted).
16 Wash out the tank, and inspect it for
cracks and chafing - renew it if damaged.
17 Refitting is the reverse of the removal
procedure. Refill the cooling system with the
proper mixture of antifreeze and water (see
Chapter 1), then start the engine and allow it
to reach normal operating temperature,
indicated by the radiator top hose becoming
hot. Recheck the coolant level and add more
if required, then check for leaks.

Note: Refer to the warnings given in Section 1
of this Chapter before starting work.

Check

1 A failure in the water pump can cause
serious engine damage due to overheating.
2 There are three ways to check the operation
of the water pump while it’s installed on the
engine. If the pump is defective, it should be
replaced with a new or rebuilt unit.
3 With the engine running at normal operating
temperature, squeeze the radiator top hose. If
the water pump is working properly, a
pressure surge should be felt as the hose is
released. 

Warning: Keep your hands away
from the radiator electric
cooling fan blades!

4 Remove the timing belt covers (see Chap-
ter 2, Part A). Water pumps are equipped with
weep or vent holes. If a failure occurs in the
pump seal, coolant will leak from the hole. In
most cases you’ll need an electric torch to
find the hole on the water pump from
underneath to check for leaks.
5 If the water pump shaft bearings fail, there
may be a howling sound at the drivebelt end
of the engine while it’s running. Shaft wear
can be felt if the water pump pulley is rocked
up and down. Don’t mistake drivebelt
slippage, which causes a squealing sound, for
water pump bearing failure.

Removal and refitting

6 Remove the timing belt and tensioner (see
Chapter 2, Part A). As noted in Chapter 2, if
the belt is fouled with coolant, it must be
renewed as a matter of course.
7 Drain the cooling system (see Chapter 1).
8 Disconnect the radiator bottom hose from
the pump union. It is easier to reach this union
if the power steering pump is unbolted and
moved aside as described in Chapter 10 (see
illustration). There is no need to disconnect
any of the power steering system hoses.
9 Unbolt and remove the water pump (see
illustration). If the pump is to be renewed,
unbolt the timing belt guide pulleys, and
transfer them to the new pump.
10 Clean the mating surfaces carefully; the
gasket must be renewed whenever it is
disturbed (see illustration).
11 On refitting, use grease to stick the new
gasket in place, refit the pump, and tighten
the pump bolts to the specified torque wrench
setting.
12 The remainder of the reassembly
procedure is the reverse of dismantling. Note
that a new tensioner spring and retaining pin
must be fitted if the timing belt has been
removed for the first time. Tighten all
fasteners to the specified torque wrench
settings, and refill the system with coolant as
described in Chapter 1.

8 Water pump - 

check, removal and refitting

3•6 Cooling, heating and air conditioning systems

7.5  Radiator mounting bracket-to-

subframe bolts (A), air conditioning system

condenser mounting bolt (B)

8.8  Power steering system pump should

be removed to reach water pump hose

union (arrowed)

8.9  Unscrew bolts (arrowed) . . .

8.10  . . . to remove water pump - always

renew gasket and clean all mating

surfaces carefully