Thermostat Housing

This procedure covers removal and replacement of the thermostat housing on the 2015-2020 Ford F-150 5.0L Coyote V8 engine, including coolant draining, housing removal, and refilling the cooling system.

Warnings

Tools required

Parts

• Thermostat housing assembly × 1 — Use OEM specification
• Thermostat housing gasket or O-ring × 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 cold before beginning work
2. Park vehicle on level surface and engage parking brake
3. Disconnect negative battery terminal to prevent electrical issues
4. Remove engine cover by pulling upward on front clips and lifting off
5. Place drain pan under radiator drain petcock location

Procedure

1. 1

   Drain cooling system
   Locate the radiator drain petcock on the lower driver side of the radiator. Open the petcock by turning counterclockwise and allow coolant to drain into the pan. If equipped, remove the coolant drain plug from the engine block on the driver side to drain additional coolant. This improves coolant recovery and reduces spillage during housing removal.
   Torque spec

   Drain Petcock8 Nm (6 lb-ft)

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

   Remove upper radiator hose
   Locate the upper radiator hose connection at the thermostat housing on the front of the engine. Use hose clamp pliers or a socket to loosen the hose clamp at the thermostat housing end. Twist the hose back and forth while pulling to break the seal and remove it from the housing. Be prepared for residual coolant spillage.
   Torque spec

   Coolant Hose Clamps5 Nm (4 lb-ft)
3. 3

   Disconnect coolant bypass hose
   The thermostat housing on the 5.0L Coyote has a smaller bypass hose connection on the side or bottom of the housing. Loosen the hose clamp and carefully remove the bypass hose from the housing nipple. Inspect the hose for cracks or deterioration and replace if necessary.
   Torque spec

   Coolant Hose Clamps5 Nm (4 lb-ft)
4. 4

   Disconnect coolant temperature sensor
   Locate the coolant temperature sensor on the thermostat housing. Press the locking tab on the electrical connector and pull straight back to disconnect. Do not pull on the wiring harness itself. Move the wiring out of the way.
   ⚠The sensor connector locking tab is plastic and can break easily. Use controlled force when disconnecting.
5. 5

   Remove thermostat housing bolts
   The thermostat housing is secured by three bolts on the 5.0L Coyote engine. Using a socket and ratchet, remove all three housing bolts completely. Keep bolts organized for reinstallation. Note the bolt locations as they may be different lengths.
   Torque spec

   Housing Bolts17 Nm (13 lb-ft)
6. 6

   Remove old thermostat housing
   With all bolts removed, carefully pull the thermostat housing straight out from the engine block. It may be stuck due to the gasket seal. If stuck, gently tap with a plastic mallet or carefully pry with a plastic scraper at a casting boss - never pry on the sealing surface. Remove the old thermostat and gasket/O-ring from the housing or engine block.
   ⚠Do not pry against machined sealing surfaces as damage will cause coolant leaks.
7. 7

   Clean sealing surfaces
   Thoroughly clean the thermostat housing mating surface on the engine block using a plastic scraper. Remove all old gasket material, coolant residue, and debris. Do not use metal scrapers that could gouge the aluminum surface. Wipe clean with shop towels and ensure the surface is completely dry and free of contamination.
   ℹ️Any debris or old gasket material left on the sealing surface will cause coolant leaks after reassembly.
8. 8

   Install new thermostat and gasket
   Install the new thermostat into the housing or engine block pocket as designed, ensuring it is properly oriented. The thermostat typically has a jiggle valve or bleed hole that should be positioned at the top (12 o'clock position) to allow air purging. Install the new gasket or O-ring onto the housing, ensuring it seats properly in the groove without twisting or pinching.
   ⚠Installing the thermostat backwards or with incorrect orientation will cause overheating. Verify the spring side faces toward the engine block.
9. 9

   Install new thermostat housing
   Carefully align the new or cleaned thermostat housing to the engine block, ensuring the gasket remains properly positioned. Start all three housing bolts by hand to ensure proper thread engagement and alignment. Once all bolts are hand-tight, torque the bolts to specification in a crisscross pattern to ensure even gasket compression.
   Torque spec

   Housing Bolts17 Nm (13 lb-ft)
10. 10

    Reconnect hoses and sensor
    Slide the bypass hose back onto the housing nipple and position the clamp over the connection area. Tighten the clamp to specification. Install the upper radiator hose onto the housing and secure with its clamp to specification. Reconnect the coolant temperature sensor electrical connector until it clicks into place.
    Torque spec

    Coolant Hose Clamps5 Nm (4 lb-ft)
11. 11

    Close drain points and refill coolant
    Close the radiator drain petcock by turning clockwise to hand tight specification. If the engine block drain plug was removed, reinstall it with a new sealing washer and torque to specification. Fill the cooling system with Motorcraft Orange coolant through the radiator cap or degas bottle until full. Follow proper 50/50 mix ratio with distilled water or use pre-mixed coolant.
    Torque spec

    Drain Petcock8 Nm (6 lb-ft)

    Coolant Drain Plug15 Nm (11 lb-ft)
12. 12

    Bleed cooling system
    With the radiator cap or degas bottle cap off, start the engine and allow it to warm up to operating temperature with the heater on maximum heat. Watch the coolant level and add coolant as needed as air purges from the system. Squeeze the upper radiator hose several times to help release trapped air. When the thermostat opens (coolant level will drop), top off coolant to the proper level. Run engine until cooling fans cycle on and off at least once.
    ⚠Keep hands and tools clear of the cooling fan which will activate automatically when the engine reaches operating temperature.

Reassembly

1. Reinstall the engine cover by aligning the rear tabs first, then pressing down firmly on the front clips until they snap into place
2. Reconnect the negative battery terminal and tighten securely
3. Verify all tools and materials are removed from the engine bay
4. Check the ground beneath the vehicle for any coolant leaks

Verification

• Start the engine and visually inspect the thermostat housing for coolant leaks while the engine warms up
• Verify the engine reaches normal operating temperature (approximately 195-220°F) and the upper radiator hose becomes hot, indicating the thermostat has opened
• Confirm the cooling fans activate when the engine reaches operating temperature
• Check coolant level in the degas bottle when engine is cold the next day and top off if necessary
• Monitor for coolant loss or leaks over the next few days of driving

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