This procedure covers the removal and replacement of heater hoses on the 2021-2024 Ford F-150 with 3.5L EcoBoost V6 engine, including coolant drainage, hose disconnection, and system refill.

Warnings

Tools required

Parts

• Heater inlet hose × 1 — Use OEM specification
• Heater outlet hose × 1 — Use OEM specification
• Hose clamps × 4 — Use OEM specification or equivalent
• Motorcraft Orange Coolant × 1 — VC-3DIL-B

Fluids

• Motorcraft Orange Coolant — 13 qt

Preparation

1. Ensure engine is completely cold to the touch
2. Park vehicle on level surface and engage parking brake
3. Place wheel chocks behind rear wheels
4. Place drain pan under radiator drain location
5. Remove engine cover by pulling upward on front edge to release clips, then pull forward

Procedure

1. 1

   Drain cooling system
   Slowly open the coolant reservoir cap to release any residual pressure. Locate the radiator drain petcock on the driver's side lower radiator tank. Attach a drain hose if available and open the petcock counterclockwise to drain coolant into the drain pan. Allow system to drain completely. Once drained, close and hand-tighten the petcock.
   Torque spec

   Drain Petcock8 Nm (6 lb-ft)
2. 2

   Access heater hoses at firewall
   The heater hoses connect to the heater core at the firewall on the passenger side of the engine bay. Remove any wire harness brackets or clips that may obstruct access to the heater hoses. Note the routing of both inlet and outlet hoses before removal for proper reinstallation.
   ℹ️Take photos of hose routing before removal to ensure correct installation of new hoses.
3. 3

   Remove heater inlet hose
   Using hose clamp pliers, compress and slide the hose clamp back from the connection point at the heater core inlet pipe (typically the upper connection). Do the same for the clamp at the engine connection point. Twist the hose gently to break the seal, then pull firmly to remove from both connection points. Residual coolant will drain, so have shop towels ready.
   ⚠Heater hoses may be stiff from heat cycling. Do not use excessive force or pry tools that could damage connection pipes.
4. 4

   Remove heater outlet hose
   Repeat the process for the heater outlet hose (typically the lower connection at the firewall). Compress and slide back the hose clamps at both ends, twist the hose to break the seal, and remove. Ensure all clamps are removed and set aside if reusable, or discard if replacing with new clamps.
5. 5

   Inspect connection points
   Examine the heater core inlet and outlet pipes at the firewall for corrosion, damage, or debris. Clean the connection surfaces with a shop towel. Check the engine-side connection points on the water pump and thermostat housing for similar issues. Any corrosion should be cleaned with a wire brush or fine sandpaper.
6. 6

   Install new heater inlet hose
   Slide new hose clamps onto the new heater inlet hose before installation. Position the hose following the original routing path. Push the hose firmly onto the heater core inlet pipe until it is fully seated against the stop. Connect the engine end to the water pump or thermostat housing connection, ensuring full seating. Position clamps approximately 1/2 inch from the hose end and tighten to specification.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
7. 7

   Install new heater outlet hose
   Install new clamps on the heater outlet hose. Route the hose following the original path, ensuring it does not contact sharp edges or moving components. Connect to the heater core outlet pipe at the firewall and the engine connection point, ensuring both ends are fully seated. Position and tighten clamps to specification.
   ℹ️Ensure hoses have adequate clearance from exhaust manifolds, turbocharger components, and drive belts.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
8. 8

   Reinstall wire harness brackets
   Reinstall any wire harness brackets or clips that were removed for access. Ensure all electrical connectors are secure and wiring is properly routed away from the new heater hoses.
9. 9

   Refill cooling system
   Using a funnel at the coolant reservoir, slowly add Motorcraft Orange Coolant until the level reaches the MAX COLD fill line. Start the engine and allow it to idle with the reservoir cap off. Continue adding coolant as the level drops while air purges from the system. Run the engine until the thermostat opens and coolant circulates (indicated by temperature gauge rising to normal operating range and upper radiator hose becoming hot).
   ⚠Engine must reach full operating temperature to purge all air from the system. Monitor temperature gauge to prevent overheating.
10. 10

    Bleed air from cooling system
    With the engine at operating temperature, increase idle to 2000 RPM for 3-5 minutes to help purge trapped air. Watch for coolant level changes in the reservoir and add as needed. Turn on the heater to maximum temperature and high fan speed. Verify hot air is blowing from vents, confirming heater core circulation. Shut off engine and allow to cool.
11. 11

    Final coolant level check
    Once engine has cooled, check coolant level in the reservoir. Add coolant to bring level to the MAX COLD line if needed. Install the coolant reservoir cap securely. Inspect all hose connections for leaks. Reinstall the engine cover by aligning rear clips first, then pressing down on front edge until clips engage.

Reassembly

1. Ensure all hose clamps are tightened to specification and positioned correctly
2. Verify coolant level is at MAX COLD line when engine is fully cooled
3. Confirm engine cover is securely clipped in place
4. Check that no tools or parts were left in engine compartment

Verification

• Start engine and allow to reach operating temperature while monitoring for leaks at heater hose connections
• Verify heater produces hot air when HVAC system is set to maximum heat
• Check for proper coolant level after first drive cycle and top off if necessary
• Inspect for coolant leaks after 24 hours and again after 100 miles of driving
• Confirm no overheating occurs and temperature gauge reads in normal range during operation

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