Cooling System: Description and Operation
Engine Cooling
NOTICE: Vehicle cooling systems are filled with Motorcraft(R) Specialty Green Engine Coolant. Do not mix coolant types. Mixing coolant types degrades the corrosion protection of the coolant. Failure to follow these instructions may result in engine or cooling system damage.
NOTICE: Genuine Mazda(R) Extended Life Coolant and Motorcraft(R) Specialty Green Engine Coolant are very sensitive to light. Do NOT allow these products to be exposed to ANY LIGHT for more than a day or two. Extended light exposure causes these products to degrade.
NOTE: Stop-leak style pellets/products must not be used as an additive in this engine cooling system. The addition of stop-leak style pellets/products can clog or damage the cooling system, resulting in degraded cooling system performance and/or failure.
The cooling system components are the:
- block heater (if equipped).
- radiator.
- bypass tube.
- pressure relief cap.
- degas bottle.
- radiator draincock.
- coolant pump.
- thermostat (cold side).
- Engine Coolant Temperature (ECT) sensor.
- variable speed fan motor assembly.
- fan control module.
- engine block coolant weep hole (3.5L only).
On 3.5L engines the coolant pump is located under the engine front cover mounted to the block. A weep hole is provided on the front left side of the engine behind the generator. It is adjacent to a 13.5 mm (0.531 in) cup plug. This plug and weep hole create a reservoir for normal coolant seepage and evaporation. Every coolant pump will have some leakage past the dynamic mechanical seal. Dampness and crusting around the weep hole is acceptable and an expected result of normal engine operation. Coolant spray or leakage amounts great enough to puddle should be addressed.
Engine coolant provides freeze protection, boil protection, cooling efficiency and corrosion protection to the engine and cooling components. In order to obtain these protections, the engine coolant must be maintained at the correct concentration and fluid level in the degas bottle.
When adding engine coolant, use a 50/50 mixture of engine coolant and distilled water. A coolant concentration of 50% will provide freeze point protection down to -36°C (-33°F).
To maintain the integrity of the coolant and the cooling system:
- add Motorcraft(R) Specialty Green Engine Coolant. Mixing different coolant types degrades the corrosion protection of the original coolant. Do not mix any type of coolants.
- do not add alcohol, methanol or brine, or any engine coolants mixed with alcohol or methanol antifreeze. These can cause engine damage from overheating or freezing.
- Ford Motor Company does NOT recommend the use of recycled engine coolant in vehicles.
- Used engine coolant should be disposed of in an appropriate manner. Follow the community's regulations and standards for recycling and disposing of automotive fluids.
Fail Safe Cooling
NOTE: If the driver is using a high percentage of throttle travel (for example, an overtaking maneuver) when the PCM starts, engine deactivation will be delayed for 10 seconds.
NOTE: After the cylinder deactivation operation has begun, the engine will not revert to operating on all cylinders, even if the temperature should fall, until the ignition is switched OFF and then ON again.
NOTE: The Malfunction Indicator Lamp (MIL) can only be extinguished by using a scan tool after the fault has been rectified and the DTC cleared.
The vehicle has a strategy built into the PCM that will control the engine if it starts to overheat.
Stage 1 of the strategy will commence if the engine starts to overheat. The Cylinder Head Temperature (CHT) sensor transmits a signal to the PCM, which then moves the temperature gauge pointer into the red zone.
If the engine is not switched OFF and the temperature continues to rise, the powertrain check lamp is illuminated. This indicates to the driver that the engine is approaching critical limits and should be stopped. At this point, DTC P1285 is set in the PCM and can be retrieved using a scan tool.
Stage 2 of the strategy will commence if the lamp and temperature gauge are ignored by the driver. The PCM will start to control the engine by cutting out cylinders and restricting the rpm to below 3,000 rpm. Simultaneously, the MIL will be illuminated. This indicates that long-term engine damage can occur and vehicle emissions will be affected. At this point, DTC 1299 is set in the PCM and can be retrieved using a scan tool.
Air is then drawn into the deactivated cylinders. This helps to control the temperature of the engine internal components. The deactivated cylinders are alternated to allow even cooling of all the cylinders.
Stage 3 of the strategy will commence if the engine temperature still continues to rise. This will result in the engine being totally disabled before major engine damage or seizure occurs. The powertrain check lamp will begin to flash, indicating to the driver that the engine will be switched OFF after 30 seconds. This allows the driver time to choose a suitable parking place.
Coolant Flow Diagram
2.5L
NOTE: Black arrows indicate hot, white arrows indicate cold.
3.0L
NOTE: Black arrows indicate hot, white arrows indicate cold.
3.5L
NOTE: Black arrows indicate hot, white arrows indicate cold.
