Ford Mid-Size Cars 1971-1985 Repair Guide

Cooling System


Check the cooling system at the interval specified in the Maintenance Interval chart at the end of this section.

Hose clamps should be tightened, and soft or cracked hoses replaced. Damp spots, or accumulations of rust or dye near hoses, water pump or other areas, indicate areas of possible leakage. Check the radiator cap for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost and the engine will overheat. A worn cap should be replaced with a new one.

Periodically clean any debris such as leaves, paper, insects, etc. from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose.

Carefully straighten any bent radiator fins with a pair of needle nose pliers. Be careful the fins are very soft.


The recommended fluid is a 50/50 mixture of antifreeze and water for year round use. Use a good quality antifreeze with water pump lubricants, rust inhibitors and other corrosion inhibitors along with acid neutralizers. Use only antifreeze that is safe for use with an aluminum radiator.


See Figures 1 through 5

The coolant level should be checked at least once a month. With the engine cold, the coolant level should be at or above the FULL COLD mark on the coolant reservoir.

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Fig. Fig. 1: If the vehicle is not equipped with a reservoir tank, check the fluid level by removing the radiator cap. Do this ONLY when the radiator is cool

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Fig. Fig. 2: If the engine is equipped with a coolant tank, coolant level is checked at the reservoir. Do not confuse it with the washer reservoir next to it

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Fig. Fig. 3: An example of a washer fluid tank next to a coolant reservoir

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Fig. Fig. 4: The coolant tank cap is usually clearly marked

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Fig. Fig. 5: If necessary, add at the water/coolant mixture to the reservoir tank

Check the appearance of the coolant. If it is dirty or rusty, it should be replaced in order to protect the cooling system from corrosion damage.

Check the coolant concentration using an antifreeze tester. The protection level should be at least -20ºF (-30ºC) to maintain the proper freeze and boil over protection and for maximum anti-rust corrosion protection.


See Figures 6 and 7

  1. Raise and safely support the vehicle on jackstands, as necessary. Refer to the Jacking procedure in this section.
  3. Position a suitable drain pan under the radiator draincock. Remove the radiator cap.

Never remove the radiator cap while the engine is running or personal injury from scalding hot coolant or steam may result. If possible, wait until the engine has cooled to remove the radiator cap. If this is not possible, wrap a thick cloth around the radiator cap and turn it slowly to the first stop. Step back while the pressure is released from the cooling system. When it is certain all the pressure has been released, press down on the cap with the cloth, then remove it.

  1. Open the radiator draincock and allow the coolant to drain into the pan.

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Fig. Fig. 6: Turn the draincock counterclockwise to drain the radiator

The cylinder block drain plugs, located on the sides of the engine block, must be removed to completely drain the system.

When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container.

  1. After the coolant has drained, close the radiator draincock and install the cylinder block drain plugs, if removed. Flush the system, if necessary.
  3. Fill the cooling system with a 50/50 mixture of water and ethylene glycol. Fill to the level of the radiator filler neck seat.

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Fig. Fig. 7: Use a funnel to add water/coolant mixture to the radiator

  1. Install the radiator cap to the first notch to keep spillage to a minimum.
  3. Place the heater temperature selector in the maximum heat position.
  5. Start the engine and let it idle until the upper radiator hose is warm. This indicates that the thermostat is open and coolant is flowing through the entire system.
  7. Stop the engine. Fill the reservoir to the correct level with the coolant mixture. Install the pressure cap securely.


To remove rust, sludge and any other foreign matter from the cooling system, it should be flushed whenever the coolant is replaced. Flushing the system restores cooling efficiency and helps avoid engine overheating.

In some cases, where a cleaning solvent is not enough to clean the system, it will be necessary to pressure flush the system. In this case, the thermostat should be removed prior to flushing. Various types of pressure flushing equipment are available; consult your auto parts store.

Radiator and Engine

The easiest way to flush the system is to use a can of liquid cooling system flush, available at most auto parts stores. Proceed as follows:

  1. After draining the cooling system, close the draincock(s) and add water and the radiator flush to the cooling system.
  3. Run the engine until the upper radiator hose gets hot, then drain the system.
  5. Repeat the process using fresh water until the drained water is clear and free of scale.

These are general radiator flushing instructions. Always follow the directions on the radiator flush container label. Make sure the flush is safe for use with an aluminum radiator.

  1. Disconnect the coolant reservoir from the system and flush it with clean water. Reconnect the reservoir to the system.
  3. Refill the cooling system, as described earlier.

Heater Core

Regardless of the type of engine cooling system flush used, the heater core must be flushed separately to prevent engine cooling system particles from clogging the heater core tubes and reducing coolant flow through the heater core. Flush the heater core as follows:

  1. Disconnect the heater core outlet hose from the water pump fitting on 5.0L or 5.8L engines, or from the return fitting on all other engines. Install a female garden hose end fitting adapter in the end of the outlet heater hose and secure with a hose clamp.
  3. Connect the female garden hose end of the outlet heater hose to the male end of a water supply garden hose.
  5. Disconnect the heater core inlet heater hose from the engine block on 5.0L or 5.8L engines, or the intake manifold fitting on all other engines. Allow the hose to drain into a suitable container.
  7. If a water valve is installed in the heater core inlet heater hose, make sure the valve is open (no vacuum).
  9. Turn the water supply valve on and off several times so the surge action will help to dislodge larger stubborn particles from the heater core tubes. Allow full water pressure to flow for about 5 minutes.
  11. If a water valve is installed in the heater core inlet hose, apply vacuum to the valve vacuum motor, using a vacuum pump, to make sure the valve is operating properly. When the valve is closed there should be no water leakage. Replace the valve, if required.
  13. Remove the hose clamp and female garden hose end adapter from the end of the outlet heater hose and reconnect the hose to the water pump fitting or heater return fitting, as required.
  15. Connect the inlet heater hose to the engine block fitting or intake manifold fitting, as required.
  17. Fill the cooling system, as described earlier. Check the heating system for proper operation.