🔧 Thermostat - Replacement

The thermostat controls coolant flow so the engine warms up correctly and stays at the right temperature. On your F-150, the thermostat sits in the coolant outlet housing and is replaced by draining some coolant, swapping the housing gasket/O-ring, and refilling the system. Use care with hot coolant and plastic fittings.

Difficulty Level: Intermediate | Estimated Time: 1.5-3 hours

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⚠️ Safety & Precautions

• Let the engine cool completely before opening the coolant system.
• Never remove the degas bottle cap when the engine is hot.
• Coolant is toxic; keep it off skin, paint, and the driveway.
• Disconnect the negative battery cable if you want extra safety near the fan and wiring.
• Keep hands clear of the cooling fan and belts if the engine is tested running.

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🔧 Required Tools

You'll need the following tools for this repair:

• 8mm socket
• 10mm socket
• Ratchet
• Short extension
• Torque wrench
• Pliers
• Drain pan
• Funnel
• Flat trim tool
• Shop towels
• Safety glasses
• Nitrile gloves
• Jack stands
• Floor jack (rated 3-ton minimum)

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Thermostat - Qty: 1
• Thermostat housing gasket or O-ring - Qty: 1
• Engine coolant (Ford-spec orange, concentrated or premix) - Qty: 1-2 gallons
• Coolant hose clamp - Qty: 1, if damaged

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📋 Before You Begin

• Park on level ground and set the parking brake.
• Let the engine cool fully before starting.
• Raise the front only if needed for access, and support it with jack stands.
• Have a drain pan ready before opening any coolant hose or housing.
• If equipped, make sure the truck is in Park and the ignition is off.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Drain enough coolant

• Place the drain pan under the radiator area.
• Open the coolant drain if accessible, or disconnect the lower hose carefully with pliers if needed.
• Drain only enough coolant to get the level below the thermostat housing.
• Work slowly to avoid spills.

Step 2: Remove intake ducting if it blocks access

• Use the 8mm socket and ratchet to remove the air intake duct fasteners.
• Move the duct aside for working room.
• Disconnect any clips or breather tubes by hand.

Step 3: Remove the thermostat housing

• Use the 10mm socket and ratchet with a short extension to remove the thermostat housing bolts.
• Lift the housing straight off.
• Catch any remaining coolant with shop towels.
• Remove the old thermostat and old gasket or O-ring.

Step 4: Clean the sealing surface

• Use a shop towel and a flat trim tool if needed to clean the mating surface.
• Do not gouge the aluminum or plastic surface.
• Make sure the surface is clean and dry before reassembly.

Step 5: Install the new thermostat

• Install the new thermostat in the same direction as the old one.
• Install the new gasket or O-ring.
• Set the housing in place by hand first.
• Use the 10mm socket to start all bolts by hand.
• Torque to 10 Nm (89 in-lbs).

Step 6: Reinstall removed intake parts

• Reinstall the intake duct and clips.
• Use the 8mm socket to tighten the fasteners.
• Make sure all hoses are fully seated.

Step 7: Refill the cooling system

• Use a funnel to refill with the correct engine coolant.
• Fill slowly to reduce air pockets.
• Top off the degas bottle to the proper level.

Step 8: Bleed air and check for leaks

• Start the engine and let it idle with the heater set to hot.
• Watch coolant level and add more as air purges out.
• Inspect the thermostat housing, hoses, and drain area for leaks.
• Watch the temperature gauge closely.

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✅ After Repair

• Drive the truck until fully warm and confirm normal temperature.
• Recheck coolant level after the engine cools down.
• Inspect again for leaks the next day.
• If the check engine light was on, clear codes with a scan tool and verify they do not return.

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💰 DIY vs Shop Cost

Shop Cost: $300-$650 (parts + labor)

DIY Cost: $60-$160 (parts only)

You Save: $240-$490 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-3 hours.

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🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.