Thermostat Housing

This procedure replaces the thermostat housing on a 2011-2014 Ford F-150 with the 3.5L EcoBoost engine, including coolant drain, housing removal, and system refill.

Warnings

Tools required

Parts

• Thermostat housing assembly × 1 — Use OEM specification
• Thermostat housing gasket × 1 — Use OEM specification
• Coolant hose clamps (if damaged) × 2 — Replace as needed

Fluids

• Motorcraft Orange Coolant — 2 qt

Preparation

1. Ensure engine is completely cool to the touch (wait minimum 2 hours after operation)
2. Park vehicle on level surface and engage parking brake
3. Disconnect negative battery terminal to prevent fan activation
4. Remove engine cover by pulling upward on cover clips
5. Place drain pan under radiator drain plug location

Procedure

1. 1

   Drain cooling system
   Locate the radiator drain plug at the bottom of the radiator on the driver side. Slowly open the drain plug and allow coolant to drain into the drain pan. Once draining slows, reinstall the drain plug finger-tight for now.
   Torque spec

   Coolant Drain Plug15 Nm (11 lb-ft)
2. 2

   Remove air intake components
   Disconnect the mass airflow sensor electrical connector. Loosen the clamp at the throttle body and remove the air intake tube. Remove the air filter housing if it obstructs access to the thermostat housing on the passenger side of the engine.
3. 3

   Locate thermostat housing
   The thermostat housing is located on the front of the engine, passenger side, below the alternator. It connects the lower radiator hose and other coolant hoses. Identify all hose connections before proceeding.
   ℹ️Take a photo of hose routing for reassembly reference.
4. 4

   Disconnect coolant hoses
   Using hose clamp pliers or a flathead screwdriver, loosen the hose clamps on all hoses connected to the thermostat housing. This typically includes the lower radiator hose and one or two smaller coolant hoses. Twist and pull hoses off the housing. Be prepared for residual coolant spillage.
   Torque spec

   Coolant Hose Clamps5 Nm (3 lb-ft)
5. 5

   Remove electrical connectors
   Disconnect any electrical connectors attached to the thermostat housing. This may include the coolant temperature sensor. Press the locking tab and pull the connector straight off.
6. 6

   Remove thermostat housing bolts
   Locate the thermostat housing mounting bolts (typically 3-4 bolts). Using the appropriate socket, remove all bolts securing the housing to the engine block. Keep bolts organized for reinstallation.
   Torque spec

   Housing Bolts16 Nm (12 lb-ft)
7. 7

   Remove old housing and gasket
   Carefully pull the thermostat housing away from the engine. The housing may be stuck due to the gasket seal. Gently pry if necessary, being careful not to damage the mating surface on the engine block. Remove the old gasket completely.
   ⚠Do not use excessive force or metal pry tools directly on aluminum mating surfaces.
8. 8

   Clean mating surfaces
   Using a razor blade scraper, carefully clean all gasket material from both the engine block mating surface and the thermostat housing mounting area. Ensure surfaces are completely clean and dry with no debris, old gasket material, or coolant residue. Wipe clean with a lint-free cloth.
9. 9

   Install new gasket and housing
   Position the new gasket on the engine block mating surface, ensuring proper alignment with bolt holes. Place the new thermostat housing onto the gasket, aligning all bolt holes. Start all mounting bolts by hand to ensure proper thread engagement.
10. 10

    Torque housing bolts
    Using a torque wrench, tighten the thermostat housing bolts to specification in a criss-cross pattern to ensure even gasket compression and prevent warping. Make multiple passes, gradually increasing torque to final specification.
    ⚠Over-tightening can crack the housing or warp the mating surface, causing leaks.
    Torque spec

    Housing Bolts16 Nm (12 lb-ft)
11. 11

    Reconnect coolant hoses
    Reconnect all coolant hoses to the new thermostat housing in their original positions. Ensure hoses are fully seated onto the housing nipples. Position hose clamps over the hose ends and tighten to specification using a torque wrench or carefully with hand tools.
    Torque spec

    Coolant Hose Clamps5 Nm (3 lb-ft)
12. 12

    Reconnect electrical connectors
    Reconnect the coolant temperature sensor and any other electrical connectors to the thermostat housing. Ensure connectors click into place and are fully seated.
13. 13

    Reinstall air intake components
    Reinstall the air filter housing if removed. Reconnect the air intake tube to the throttle body and tighten the clamp securely. Reconnect the mass airflow sensor electrical connector.
14. 14

    Refill and bleed cooling system
    Ensure the radiator drain plug is torqued to specification. Reconnect the negative battery terminal. Fill the cooling system with Motorcraft Orange Coolant through the degas bottle (coolant reservoir) until it reaches the COLD FILL MAX line. Start the engine and allow it to reach operating temperature with the degas bottle cap off. Add coolant as needed as air purges from the system. Watch for coolant circulation and verify the upper radiator hose becomes hot.
    ⚠Monitor engine temperature gauge closely. If temperature rises above normal, shut off engine immediately and recheck for air pockets or leaks.
    Torque spec

    Coolant Drain Plug15 Nm (11 lb-ft)
15. 15

    Final checks and top-off
    Once the engine reaches operating temperature and the thermostat opens, turn the heater to maximum heat and verify hot air blows from vents. Shut off the engine and allow to cool. Recheck coolant level when cool and top off to COLD FILL MAX line. Install the degas bottle cap. Reinstall the engine cover.

Reassembly

1. Verify all hose clamps are properly tightened and positioned
2. Ensure all electrical connectors are fully seated with locking tabs engaged
3. Confirm no tools or parts were left in the engine bay
4. Double-check coolant level at degas bottle after initial test drive

Verification

• Start the engine and visually inspect the thermostat housing area for any coolant leaks while engine warms up
• Verify engine reaches normal operating temperature (approximately halfway on gauge)
• Confirm heater produces hot air when set to maximum temperature
• Check for proper coolant level in degas bottle when engine is cool
• After first drive cycle, re-inspect for leaks and verify coolant level has not dropped
• Scan for any diagnostic trouble codes related to coolant temperature sensors

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