Engine Cooling Fan Ford Thunderbird IX

DESCRIPTION

The basic liquid cooling system consists of a radiator, water pump, thermostat, cooling fan, pressure cap, heater (if equipped), various connecting hoses and cooling passages in the block and cylinder head. In addition, many cars use a fan clutch (incorporating a thermostatic control) or flexible fan blade. These reduce noise and power requirements at higher engine speeds.

Some models may use a thermostatic vacuum switch to advance ignition timing in the event of overheating. Most models use a coolant recovery system to prevent loss of anti-freeze.

DRAINING

Remove radiator cap and open heater control valve to maximum heat position. Open drain cocks or remove plugs in bottom of radiator and in engine block. In-line engines usually have one plug or cock, while "V" type engines will have two, one in each bank of cylinders.

CLEANING

A good cleaning compound removes most rust and scale. Follow manufacturer's instructions in the use of the cleaner. If considerable rust and scale has to be removed, flushing should be used. Clean radiator air passages by blowing with compressed air from back to front of radiator.

FLUSHING

1. Back flushing is a very effective means of removing rust and scale from a cooling system. For best results, the radiator, engine and heater core should be flushed separately.
2. To flush radiator, connect flushing gun to water outlet of radiator and disconnect water inlet hose. Use a leadaway hose, connected to radiator inlet, to prevent flooding the engine. Use air in short bursts only as a clogged radiator could be easily damaged. Continue flushing until water runs clear.
3. To flush engine, first remove thermostat and replace housing. Connect flushing gun to water outlet of engine. Disconnect heater hoses from engine. Flush using short air bursts until water runs clean. Flush heater core as described for radiator. Make sure heater valve is set to maximum heat position before flushing heater.

REFILLING

Engine should be running while refilling cooling system to prevent air from being trapped in the engine block. After system is full, continue running engine until thermostat is open, then recheck fill level. Do not overfill system. Refer to appropriate article for correct cooling system capacity.

Scheme 1

1. Visually inspect thermostat for corrosion and proper sealing of valve and seat. If satisfactory, suspend thermostat and a thermometer in a container with a 50/50 mixture of anti-freeze and water (AMC recommends 100% anti-freeze). (Scheme 1)
2. Do not allow either thermostat or thermometer to touch bottom of container as this concentration of heat could cause an incorrect reading. Heat water until thermostat just begins to open. (Scheme 1): Testing Thermostat in Anti-Freeze/Water Solution NOTE: Support thermometer so it does not touch bottom of container.
3. Read temperature on thermometer. This is the initial opening temperature and should be within specifications. Continue heating water until thermostat is fully open and note temperature. This is the fully opened temperature. If either reading is outside of specifications, replace thermostat, as it is not adjustable.

PRESSURE TESTING RADIATOR CAP

A pressure testing tool is used to test both radiator cap and complete cooling system. Test as follows, following tool manufacturer's instructions.

Visually inspect radiator cap, then dip cap in water and connect to tester. Pump tester to bring pressure to upper limit of cap specifications. If cap fails to hold pressure within specifications, replace cap.

Testing Radiator Pressure Cap. Scheme 2

Note. Wet cap gasket before testing.

Scheme 3

1. With engine off, wipe radiator filler neck seat clean. Fill radiator to correct level. Attach tester to radiator and pump until pressure is at upper limit of radiator rating.
2. If pressure drops, inspect for external leaks. If no leaks are apparent, detach tester and run engine until normal operating temperature is obtained. Reattach tester and observe. If pressure builds up immediately, a possible leak exists from a faulty head gasket or crack in head or block. CAUTION: Pressure may build up quickly. Release any excess pressure or cooling system damage may result.
3. If there is no immediate pressure build up, pump tester to within system pressure range (on radiator cap). Vibration of gauge pointer indicates compression or combustion leak into cooling system. Isolate leak by shorting each spark plug wire to cylinder block. Gauge pointer should stop or decrease vibration when leaking cylinder is shorted. CAUTION: Do not disconnect spark plug wires while engine is operating, or operate engine with spark plug shorted for more than 1 minute as catalytic converter may be damaged.
4. Remove engine and transmission (automatic only) oil dipsticks and check if water drops appear in oil. If so, a serious internal leak is indicated. If all checks are negative and system holds pressure for 2 minutes, there are no serious leaks in system. (Scheme 3): Pressure Testing Cooling System NOTE: Pump up to specified pressure.

ANTI-FREEZE CONCENTRATION

Note. On models using aluminum engines or cooling system components, refer to Owners Manual for anti-freeze requirements and recommendations. Aluminum components require a different formulation of anti-freeze to prevent corrosion.

On all cooling systems, test anti-freeze concentration using anti-freeze tester. Tester should have a temperature-compensating feature, as failing to take temperature into consideration could cause an error as large as 30°F. Follow tester manufacturer's instructions for correct use of tester.

A coolant recovery system differs from other cooling systems in that an overflow bottle is connected to the radiator overflow hose. The overflow bottle is transparent or translucent to permit checking of coolant level without removing radiator cap. No adjustment or test is required except keeping vent hole or hose clean and checking pressure relief of radiator cap.

OPERATION

As coolant temperature rises and pressure in system exceeds pressure relief valve of radiator cap, excess coolant flows into overflow bottle. As engine cools and coolant contracts, a vacuum is formed in the system. The vacuum draws coolant, stored in overflow bottle, back into radiator. In a properly maintained cooling system, the only coolant losses will be through evaporation.

Typical Coolant Recover System. Scheme 4

Note. Overflow bottle captures and releases coolant according to temperature.

Front Wheel Drive Models, All 2.3L Engine with A/C & 3.8L Capri/Mustang

All electrically-driven fans are actuated by thermal relay switches. Thermal switches turn fan motor on when necessary and shut fan motor off when not needed. All air conditioned vehicles are equipped with over-ride switches. These switches turn fan motor on whenever air conditioning system is operating, and return fan motor control to thermal relay when system is turned off.

Although all electric fans operate on same principle, the following are special descriptions that apply to specific models

Coolant temperature switch activates coolant relay to provide battery power to fan motor when engine temperature reaches 221°F (105°C); relay shuts fan off when temperature drops sufficiently. After vehicle operation or when carburetor temperature exceeds 155°F (68°C), carburetor temperature relay switch activates timer relay. Timer relay turns fan on for a period of 15 minutes or until temperature drops to 155°F (68°C) or less.

Note. Timer relay works only when ignition switch is turned off. Avoid working around fan with ignition off when temperature at carburetor may exceed 155°F (68°C).

TESTING

If fan is not operating properly, disconnect fan motor wire connector and connect it with 14 gauge wire to a good 12-volt battery. If fan runs, motor is all right, indicating car battery, radiator fan switch (Chrysler), coolant relay, timer relay (Ford), coolant temperature switch (GM) or A/C relay (all models) may be defective. If fan motor does not run when connected directly to a good battery, replace fan motor.

Thermostatically Controlled Electric Fan. Scheme 5

Cooling Fan Controller Diagnosis - Tempo/Topaz, Escort/Lynx (EFI), EXP (EFI)

If it is suspected that the cooling fan controller is not operating properly, diagnosis of the controller can be performed by taking voltage readings at the controller connector when the connector is plugged into the controller.

Note. The electronic switches within the controller are shown as relays in the following schematics to simplify the circuit and make it easier to understand. With the exception of the A/C fan control relay, some switching within the controller is done with electronic circuits and not with relays as shown.

The voltage readings should be made during the following condition

1. Ignition switch in run - engine running and A/C "ON"

The voltage readings shown should be obtained at the indicated connector pins. If the indicated voltage/continuity reading is not present, refer to the appropriate WIRING DIAGRAMS article in the WIRING DIAGRAMS Section to determine where the problem is (in the circuits connected to the controller or within the controller).

The Component Location for the Cooling Fan Controller is behind the glove box.

IGNITION SW. IN RUN - ENG. RUNNING & A/C "ON" (U.S.A.)

IGNITION SW. IN RUN - ENG. RUNNING & A/C "ON" (DIESEL)

IGNITION SW. IN RUN - ENG. RUNNING & A/C "ON" (CANADA)

This unit is a fixed blade assembly designed to flex the blades as the engine RPM increases. As RPM increases blade pitch decreases, thereby saving power and decreasing noise level. No adjustment or test is required beyond keeping the fan belt adjusted to the proper tension.

Flex Blade Fan Assembly. Scheme 6

Most air conditioned models use a thermostatically controlled fluid fan and torque control clutch. The thermal control drive is a silicone-filled coupling connecting the fan to the fan pulley, and is operated by a control valve. Control valve is operated by a temperature sensitive bimetal coil or strip and controls the flow of silicone through the clutch.

During periods of operation when radiator discharge air temperature is low, the fan clutch limits the fan speed. High radiator discharge air temperature causes bimetal to allow a greater flow of silicone to enter the clutch. This increases the drag between the driven member and driving member resulting in a higher fan speed and increased cooling.

In cases of engine overheating or insufficient air conditioning proceed with the following tests

Scheme 7

1. Start with a cool engine to ensure complete fan clutch disengagement.
2. Cover radiator grille sufficiently to induce high engine temperature.
3. Start engine and operate at 2000 RPM. Turn on air conditioning if equipped.
4. A fan roar will be noticed when the fan clutch engages. (Scheme 7): Thermostatically Controlled Fan Assembly NOTE: Shown with stamped face and bi-metal coil spring. NOTE: It will take approximately 5 to 10 minutes for the temperature to become high enough to allow engagement of the fan clutch. While operating engine under these conditions, observe temperature light to prevent overheating. If hot light comes on, remove cover from radiator grille.
5. As soon as the clutch engages, remove the radiator grille cover and turn the A/C off to assist in engine cooling.
6. After several minutes the fan clutch should disengage. This can be determined by a reduction in fan speed and roar. If the fan fails to function as decribed, it should be replaced.