here's the ford way:
1991 Ford Truck Explorer 2WD V6-245 4.0L (includes 4WD)
Cooling System: Service and Repair
Filling and Bleeding
*** THIS ARTICLE REFLECTS CHANGES MADE BY TSB 95910 DATED JANUARY 16, 1995
WARNING: Never remove the radiator cap under any conditions while the engine is operating. Failure to follow this instruction could result
in damage to the cooling system or engine and/or cause personal injury. Use extreme care when removing the radiator cap from a hot radiator.
If possible, wait until engine has cooled, then 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 you are sure all the pressure has been released, press down on the radiator cap (still using a
cloth), turn and remove it.
NOTE: In order to bleed the cooling system properly after an initial fill with coolant, it might need up to five (5) cycles of the following:
1. Heating up the system (thermostat open).
2. Ensuring coolant is at least up to the "cold" fill mark of the overflow bottle.
3. Letting coolant cool down (temperature gauge below "N" of normal).
4. Topping off coolant overflow to "cold" mark.
5. Repeating cycle.
FILLING
WARNING: Use caution when adding coolant mixture to radiator to avoid hot coolant or steam blow out from the radiator.
NOTE: Use the following steps to remove air from the cooling system and to ensure a complete fill can be accomplished.
NOTE: When filling a crossflow radiator, allow time for the coolant to flow through the radiator tubes to the other end tank to ensure radiator is
full.
1. Close radiator draincock and install cylinder block drain plug.
2. Fill the cooling system with a 50/50 ethylene glycol and water mixture. Allow several minutes for trapped air to escape (bubble out) and for
coolant mixture to flow through the radiator.
3. Install radiator cap to pressure relief position by installing radiator cap to fully-installed position and then backing off to first stop. This will allow
any air to escape and minimize spillage.
4. Slide heater temperature and mode selection levers to maximum heat position.
5. Start engine and allow to operate at fast idle (approximately 2000 rpm) for 3 to 4 minutes. Shut engine off.
6. With engine off, wrap radiator cap with a thick cloth, carefully remove radiator cap and add coolant to bring coolant level up to filler neck seat.
7. Replace radiator cap to fully-installed position. Then, back off to first stop. Operate engine at fast idle until the upper radiator hose is warm
(water thermostat opens). To check radiator, shut engine off, wrap radiator cap with thick cloth and carefully remove radiator cap. Add additional
coolant if necessary. Replace radiator cap to fully-installed position.
8. Open the small cap on the top of the radiator coolant recovery reservoir. The large cap is for the windshield washer reservoir. Never put coolant
mixture in windshield washer bottle.
9. Using a suitable suction gun, remove all coolant from radiator coolant recovery reservoir.
10. Add 1 liter (1.1 quart) of 50/50 mixture of ethylene glycol and water to the radiator coolant recovery reservoir. Close small cap.
