Ford Aerostar 1986-1997 Repair Guide

Cooling System


See Figure 1

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Fig. Fig. 1: Read the coolant caution label before performing any service on the cooling system


See Figure 2

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Fig. Fig. 2: Cutaway view of a typical cooling system flow

At the factory, the cooling system is filled with a 45-55% mixture (50-50% for Canada, Seattle, Salt Lake City and Twin Cities) of Ford Cooling System Fluid part number E2FZ-19549-A and distilled water. The Aerostar is equipped with an aluminum radiator and the factory coolant has a special corrosion inhibiting formula to prevent damage to the radiator. If the Ford type coolant is not available, a good quality antifreeze meeting ESE-M97B44-A standards should be used. Do not use alcohol or methanol based antifreeze in any quantity or mixture. The use of the wrong coolant may result in radiator and engine damage. The 45-55 and 50-50 mixtures should be maintained at all times. A coolant mixture of less than 30% will result in corrosion of the engine block and overheating.


See Figures 3, 4, 5 and 6

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Fig. Fig. 3: Carefully remove the radiator cap if checking the fluid level in the radiator

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Fig. Fig. 4: Use a funnel to add coolant

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Fig. Fig. 5: Periodically remove all debris from the radiator fins

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Fig. Fig. 6: Be sure the rubber gasket on the radiator cap has a tight seal

The coolant level is checked at either the radiator, if the vehicle is not equipped with a coolant recovery system, or at the coolant recovery tank, if equipped.

The coolant level should be checked in both the radiator and recovery reservoir at least once a month and then only when the engine is cool. Never, under any circumstances, attempt to check the coolant level in the radiator when the engine is hot or operating. On a full system, it is normal to have coolant in the expansion reservoir when the engine is hot.

Whenever coolant level checks of the radiator are made, check the condition of the radiator cap rubber seal. Make sure it is clean and free of any dirt particles. Rinse with water, if necessary, and make sure the radiator filler neck seat is clean. Check that the overflow hose is not kinked and is attached to the reservoir. If you have to add coolant more than once a month, or if you have to add more than one quart at a time, check the cooling system for leaks.


See Figures 7 and 8

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Fig. Fig. 7: Loosen the radiator draincock to drain the coolant

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Fig. Fig. 8: Cooling systems should be pressure tested for leaks periodically

Never attempt to check the radiator coolant level while the engine is hot. Use extreme care when removing the radiator cap. Wrap a thick towel around the cap and turn it slowly to the first stop. Step back while the pressure is released from the cooling system. When all pressure has vented, press down on the cap (still wrapped in the towel) and remove it. Failure to follow this procedure may result in serious personal injury from hot coolant or steam blowout and/or damage to the cooling system.

A standard ethylene glycol hydrometer is used to check the coolant concentration. It is available at all automotive parts stores and most supermarkets for about a buck. No tool box should be without one.

On systems with a coolant recovery tank, maintain the coolant level at the level marks on the recovery bottle. The coolant should be at the base of the filler neck in the radiator. The Aerostar uses an aluminum radiator and requires coolant with corrosion inhibitors to prevent radiator damage. Use only a permanent type coolant that meets Ford specification ESE-M97B44-A. Do not use alcohol or methanol antifreeze.

For best protection against freezing and overheating, maintain an approximate 45-55% water and 45-55% ethylene glycol antifreeze mixture in the cooling system. Do not mix different brands of antifreeze to avoid possible chemical damage to the cooling system. Avoid using water that is known to have a high alkaline content or is very hard, except in emergency situations. Drain and flush the cooling system as soon as possible after using such water.

Never add cold water to an overheated engine while the engine is not running.

After filling the radiator, run the engine until it reaches normal operating temperature, to make sure that the thermostat has opened and all the air is bled from the system.


When draining the 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. Coolant should be reused unless it is contaminated or several years old.

To drain the cooling system, allow the engine to cool down BEFORE ATTEMPTING TO REMOVE THE RADIATOR CAP . Then turn the cap slowly in case any pressure remains. If there is any remaining pressure, wait until all pressure is relieved before removing the cap completely. To avoid burns and scalding, always handle a warm radiator cap with a heavy rag.

  1. At the dash, set the heater TEMP control lever to the fully HOT position.
  3. With the radiator cap removed, drain the radiator by loosening the petcock at the bottom of the radiator. Flush the radiator with water until the fluid runs clear. Disconnect the lower radiator hose from the radiator and drain any remaining coolant from the engine block.
  5. Close the petcock and reconnect the lower radiator hose, then refill the system with a 50/50 mix of ethylene glycol antifreeze and water. Fill the system to the bottom of the radiator filler neck, then reinstall the radiator cap after allowing several minutes for trapped air to bubble out. Back the radiator cap off to the first stop (pressure relief position).

Fill the fluid reservoir tank up to the MAX COLD level.

  1. Operate the engine at 2000 rpm for a few minutes with the heater control lever in the MAX HEAT position.
  3. Turn the engine OFF , then wrap a rag around the radiator cap and remove it. Be careful, the coolant will be hot. Top off the radiator coolant level, if necessary, then reinstall the radiator cap to its down and locked position.
  5. Start the engine and allow it to reach normal operating temperature, then check the system for leaks.


Allow the engine to cool sufficiently before attempting to remove the radiator cap. Use a rag to cover the cap, then remove by pressing down and turning counterclockwise to the first stop. If any hissing is noted (indicating the release of pressure), wait until the hissing stops completely, then press down again and turn counterclockwise until the cap can be removed.

DO NOT attempt to remove the radiator cap while the engine is hot. Severe personal injury from steam burns can result.

Check the condition of the radiator cap gasket and seal inside of the cap. The radiator cap is designed to seal the cooling system under normal operating conditions which allows the build up of a certain amount of pressure (this pressure rating is stamped or printed on the cap). The pressure in the system raises the boiling point of the coolant to help prevent overheating. If the radiator cap does not seal, the boiling point of the coolant is lowered and overheating will occur. If the cap must be replaced, purchase the new cap according to the pressure rating which is specified for your vehicle.

Prior to installing the radiator cap, inspect and clean the filler neck. If you are reusing the old cap, clean it thoroughly with clear water. After turning the cap on, make sure the arrows align with the overflow hose.