Replace the thermostat on a 2011-2014 Ford F-150 with 5.0L Coyote V8 engine to restore proper engine temperature regulation.

Warnings

Tools required

Parts

• Thermostat with housing gasket × 1 — Motorcraft RT-1266 or equivalent
• Thermostat housing gasket × 1 — Use OEM specification
• Lower radiator hose clamp × 1 — Use OEM specification if damaged

Fluids

• Motorcraft Orange Coolant — 4 qt

Preparation

1. Ensure engine is completely cold to the touch before beginning work
2. Park vehicle on level ground and engage parking brake
3. Place drain pan under the lower radiator hose connection at the thermostat housing
4. Locate thermostat housing on the lower front driver side of the engine block where the lower radiator hose connects

Procedure

1. 1

   Drain cooling system
   Open the cooling system bleed screw located on the thermostat housing or nearby coolant passage using an 8mm socket. Loosen the lower radiator hose clamp at the thermostat housing and carefully pull the hose off to drain coolant into the drain pan. Allow coolant to drain completely.
2. 2

   Remove coolant temperature sensor
   Disconnect the electrical connector from the coolant temperature sensor on the thermostat housing. Using a 10mm socket, remove the coolant temperature sensor from the housing and set aside. Inspect sensor O-ring for damage.
3. 3

   Remove thermostat housing bolts
   Using a 10mm socket, remove the two thermostat housing bolts securing the housing to the engine block. Note the bolt positions as they may be different lengths. Carefully pull the housing away from the engine block.
   Torque spec

   Thermostat Housing Bolts15 Nm (11 lb-ft)
4. 4

   Remove old thermostat and gasket
   Remove the old thermostat from the engine block opening, noting the orientation of the spring side (faces into the engine). Remove and discard the old gasket from both the housing and engine block mating surfaces.
5. 5

   Clean mating surfaces
   Using a plastic scraper, thoroughly clean both the thermostat housing and engine block mating surfaces. Remove all old gasket material, corrosion, and debris. Wipe clean with shop towels. Both surfaces must be completely clean and dry for proper seal.
   ⚠Do not use metal scrapers or abrasive pads that could gouge the aluminum surfaces and create leak paths.
6. 6

   Install new thermostat
   Place the new thermostat into the engine block opening with the spring side facing into the engine block. Ensure the thermostat is fully seated in the recess and the air bleed valve (small hole or notch) is positioned at the top.
7. 7

   Install new gasket and housing
   Position the new gasket onto the engine block, aligning with the dowel pins if present. Carefully position the thermostat housing over the thermostat and gasket, ensuring proper alignment. Hand-thread both housing bolts to prevent cross-threading.
8. 8

   Torque housing bolts
   Using a torque wrench, tighten the thermostat housing bolts in a criss-cross pattern to 16.0 Nm (12 lb-ft). Verify both bolts are properly torqued and the housing is seated evenly against the engine block.
   Torque spec

   Thermostat Housing Bolts15 Nm (11 lb-ft)
9. 9

   Reinstall coolant temperature sensor
   Apply a small amount of thread sealant to the coolant temperature sensor threads. Install the sensor into the thermostat housing and torque to 20.0 Nm (15 lb-ft) using a torque wrench. Reconnect the electrical connector.
   Torque spec

   Coolant Temperature Sensor20 Nm (15 lb-ft)
10. 10

    Reconnect lower radiator hose
    Slide the lower radiator hose onto the thermostat housing outlet, ensuring it is fully seated past the barb. Position the hose clamp over the connection point and torque to 5.0 Nm (4 lb-ft).
11. 11

    Fill and bleed cooling system
    With the bleed screw open, slowly pour Motorcraft Orange Coolant into the radiator or coolant reservoir until coolant flows from the bleed screw without air bubbles. Close the bleed screw to 8.0 Nm (6 lb-ft). Continue filling the system to the COLD MAX mark on the reservoir. Install the radiator cap.
    ℹ️Filling slowly prevents air pockets from forming in the cooling system. Air pockets can cause overheating and incorrect temperature readings.
12. 12

    Perform initial test run
    Start the engine and allow it to reach normal operating temperature with the heater on full hot. Monitor the temperature gauge for normal operation (approximately halfway). Check for leaks around the thermostat housing, sensor, and hose connection.
13. 13

    Burp cooling system and top off
    After the engine reaches operating temperature and the cooling fans cycle on, turn off the engine and allow it to cool for 30 minutes. Check the coolant level in the reservoir and add coolant as needed to bring it to the COLD MAX mark. Repeat this process if the level drops significantly.

Reassembly

1. Verify all hose clamps are properly tightened and positioned
2. Ensure the coolant temperature sensor electrical connector is fully seated and locked
3. Check that no tools or rags were left in the engine bay
4. Wipe down any coolant residue from engine components and surrounding areas

Verification

• Start the engine and verify it reaches normal operating temperature within 5-10 minutes of driving
• Confirm the temperature gauge reads in the normal range (approximately center position)
• Check that the cabin heater produces hot air when set to maximum temperature
• Inspect all connections for coolant leaks after the first test drive
• After 24-48 hours of driving, recheck coolant level and top off if necessary - some air may continue to purge from the system
• Verify the cooling fans activate when the engine reaches operating temperature

More procedures for this vehicle