Description and principle of operation of engine cooling

Cars with 1.6L Zetec-SE/1.4L engine

Pos.	Spare Part No	Name
1	-	Expansion tank of the cooling system
2	-	Thermostat
3	-	Cooling Fan Motor and Housing
4	-	Radiator
5	-	Water pump

Cars with 1.6L Duratec engine

Pos.	Spare Part No	Name
1	-	Water pump
2	-	Thermostat housing
3	-	Thermostat
4	-	Thermostat cover
5	-	Cooling Fan Shroud
6	-	Radiator
7	-	Expansion tank of the cooling system

Cars with 1.8L/2.0L/1.6L Zetec-E engine

Pos.	Spare Part No	Name
1	-	Water pump
2	-	Thermostat
3	-	Radiator
4	-	Cooling Fan Motor and Housing
5	-	Expansion tank of the cooling system

Cars with 1.8L Diesel engine

Pos.	Spare Part No	Name
1	-	Expansion tank of the cooling system
2	-	Thermostat
3	-	Electric motor and casing
4	-	Radiator
5	-	Water pump

The paraffin-filled thermostat ensures rapid engine warm-up. This is achieved by limiting the coolant flow at low operating temperatures. The thermostat also helps maintain the engine operating temperature within predetermined limits.

WARNING: When working in the immediate vicinity of the engine cooling fan, disconnect the battery cables. The fan is controlled by the engine management system and an increase in coolant temperature may cause the fan to turn on even when the ignition is off. Failure to follow this instruction may result in personal injury.

The cooling fan(s) are enclosed in a shroud located behind the radiator.

Engine coolant

WARNING: Engine coolant contains monoethylene glycol and other additives which are toxic if ingested and may be absorbed through the skin after prolonged contact.

The engine coolant concentration should be checked with a hydrometer (areometer) through the neck of the expansion tank. The acceptable range of operating density (sg) of correctly balanced fluids is between 1.06 and 1.07 kg/l, which corresponds to an engine coolant concentration in the range between 40% and 55%. If the concentration falls below 40%, there is insufficient protection against the effects of low temperatures and corrosion resistance is insufficient. In such cases, the concentration should be brought up to standard.


The coolant used may be either Motocraft Super Plus 4, which is blue-green, or Motocraft Super Plus 2000, which is orange. Motocraft Super Plus 4 is a non-silicified organic acid technology (OAT) coolant and should not be mixed with other types of coolant. When adding coolant, use only coolant that meets the correct specification and is compatible with the existing coolant. For more information, refer to the Specifications section of this section.

Replacing the coolant

WARNING: When relieving pressure in the cooling system, cover the expansion tank cap with a thick cloth to prevent the risk of scalding from coolant. Failure to do so may result in injury.

CAUTION: When draining the coolant or replacing any cooling system components, do not allow coolant to come into contact with the timing belt or accessory drive belt. If necessary, remove the belt. Contamination of the belt may cause damage.

NOTE: Provided that the coolant is not contaminated with other fluids or foreign matter, the good anti-corrosion properties of this fluid allow it to be reused after replacing aluminum cooling system components, but the fluid concentration should always be checked and maintained within specification.

This coolant should be changed at 10 years or 150,000 miles, whichever comes first. Fill the cooling system only with coolant that meets the correct specification and is compatible with the existing coolant. For more information, refer to the Specifications section of this section.

Reliable cooling

The engine's powertrain control module (PCM) has a strategy that will control the engine if it begins to overheat.


If the engine starts to overheat, the first stage of the strategy is activated. The cylinder head temperature sensor (CHT) sends a signal to the PCM, which commands the temperature gauge needle to move into the red zone.

If the engine does not shut off and the temperature continues to rise, the Power Train Check light will come on. This tells the driver that the engine is approaching critical limits and should be stopped. At this point, the PCM generates DTC p1285, which can be retrieved using WDS.

If the driver ignores the warning lamp and the temperature gauge, the 2nd stage of the strategy is activated. The PCM starts to control the engine with two cylinders off and the engine speed is limited to a value not exceeding 3000 rpm. At the same time, the Malfunction Indicator Lamp (MIL) comes on. This indicates that significant irreparable damage to the engine may occur and this will affect the emission level. At this point, the PCM generates DTC p1299, which can be retrieved using WDS.

Air is sucked into the deactivated cylinders, which help regulate the temperature of the internal engine components. Cylinder deactivation alternates between cylinders, which helps ensure uniform cooling of all cylinders.

NOTE: If the driver uses high throttle travel (e.g. during an overtaking maneuver) when the PCM initiates engine shutdown (stage 2), shutdown will be delayed for 10 seconds.

NOTE: Once 2-cylinder operation is activated, the engine will not return to 4-cylinder operation even if the temperature should drop until the ignition is turned off and then back on.

NOTE: The MIL can only be cleared using WDS after the fault has been repaired and the DTC has been cleared.

If the engine temperature continues to rise, the 3rd stage of the strategy is activated. This results in the complete shutdown of the engine before serious damage or seizure occurs. The check engine light starts to flash, indicating to the driver that the engine will be shut off in 30 seconds. This gives the driver time to select a suitable parking place.