Radiator Hoses - Both

Complete replacement of both upper and lower radiator hoses on a 1972 Ford F-100 with 302ci V8 engine, including coolant drain and refill procedures.

Warnings

Tools required

Parts

• Upper radiator hose × 1 — Use OEM specification or quality aftermarket
• Lower radiator hose × 1 — Use OEM specification or quality aftermarket
• Hose clamps (worm-drive style) × 4 — 1.25-1.75 inch diameter range

Fluids

• Ethylene glycol green 50/50 coolant — 15 qt

Preparation

1. Ensure the engine is completely cold to the touch.
2. Park the vehicle on level ground and engage the parking brake.
3. Place the drain pan underneath the radiator drain petcock located at the bottom passenger side of the radiator.
4. Remove the radiator cap slowly by pressing down and turning counterclockwise to release system pressure.

Procedure

1. 1

   Drain the cooling system
   Open the radiator drain petcock by turning it counterclockwise with pliers or by hand. Allow all coolant to drain into the catch pan. If the petcock is stuck or corroded, carefully remove the lower radiator hose at the radiator instead to drain the system. Wait until flow stops completely.
2. 2

   Remove the upper radiator hose clamps
   Locate the upper radiator hose running from the top of the radiator to the thermostat housing on the engine. Using a flathead screwdriver or pliers, loosen the worm-drive clamps at both the radiator neck and thermostat housing connections. Slide the clamps away from the connection points, positioning them toward the middle of the hose.
3. 3

   Remove the upper radiator hose
   Twist the upper hose back and forth while pulling to break the seal and remove it from both the radiator and thermostat housing. If the hose is stuck due to age, carefully work a flathead screwdriver between the hose and fitting to break the bond, or make a lengthwise cut in the old hose with a utility knife to split it off without damaging the metal fittings.
4. 4

   Remove the lower radiator hose clamps
   Locate the lower radiator hose running from the bottom of the radiator to the water pump inlet at the front of the engine block. Loosen the worm-drive clamps at both the radiator outlet and water pump inlet using a flathead screwdriver or pliers. Slide the clamps toward the center of the hose.
5. 5

   Remove the lower radiator hose
   Twist and pull the lower hose to remove it from both the radiator and water pump connections. Use the same technique as with the upper hose if it is stuck. Allow any remaining coolant to drain into the catch pan.
6. 6

   Clean the connection surfaces
   Inspect the radiator inlet and outlet necks, thermostat housing, and water pump inlet for corrosion, cracks, or damage. Use a wire brush and shop towels to thoroughly clean all four connection surfaces, removing old coolant residue, rubber deposits, and corrosion. Ensure all surfaces are smooth and free of debris that could prevent a proper seal.
7. 7

   Install the new lower radiator hose
   Slide new worm-drive clamps onto both ends of the new lower radiator hose before installation. Position the hose onto the radiator outlet first, ensuring it seats fully onto the neck, then connect the other end to the water pump inlet. Verify the hose routing does not contact the fan, belts, or any sharp edges. Position the clamps approximately 0.5 inches from the end of each connection and tighten them securely with a screwdriver until snug but not overtightened.
8. 8

   Install the new upper radiator hose
   Slide new worm-drive clamps onto both ends of the new upper radiator hose. Install the hose onto the radiator neck first, pushing it on until it bottoms out, then connect the other end to the thermostat housing. Ensure proper routing with no kinks or contact with moving parts. Position the clamps approximately 0.5 inches from the end of each connection and tighten securely.
9. 9

   Close the drain system
   If you used the radiator drain petcock, close it by turning clockwise until snug. Do not overtighten as these are often made of plastic or soft brass.
10. 10

    Refill the cooling system
    Using a funnel, slowly pour fresh 50/50 premixed ethylene glycol green coolant into the radiator until it reaches the bottom of the filler neck. Pause periodically to allow air bubbles to escape. Fill until the coolant level is stable at the top of the radiator core. On 1972 F-100 systems without an overflow tank, fill to approximately 1 inch below the filler neck when cold.
11. 11

    Burp the cooling system
    With the radiator cap still off, start the engine and allow it to idle. Watch the coolant level and add more as needed as the thermostat opens and air pockets are purged from the system. The upper radiator hose should become hot to the touch once the thermostat opens (typically around 180-195°F). Continue running until the cooling fan cycles on or the engine reaches normal operating temperature. Squeeze the upper radiator hose several times to help release trapped air bubbles.
12. 12

    Final fill and cap installation
    With the engine at operating temperature, top off the coolant to the proper level (bottom of filler neck). Install the radiator cap by pressing down and turning clockwise until it locks into place. Allow the engine to continue running for several minutes and verify no leaks are present at any hose connections.

Reassembly

1. Double-check all four hose clamp connections are tight and positioned correctly.
2. Wipe down all hose connections and the radiator to make it easier to spot any future leaks.
3. Dispose of old coolant at an appropriate recycling facility or auto parts store that accepts used coolant.

Verification

• With the engine at operating temperature, visually inspect all four hose connections for coolant leaks.
• Verify the upper radiator hose becomes hot when the engine reaches operating temperature, indicating proper coolant circulation.
• Check that the coolant level remains stable after the initial heat cycle and does not drop significantly.
• Squeeze the upper radiator hose when warm—it should feel firm due to system pressure, indicating a proper seal at the radiator cap.
• After the first drive cycle, recheck coolant level when cold and top off if necessary, as additional air may have purged from the system.

More procedures for this vehicle