🔧 Fusion - Thermostat Replacement

Replacing the thermostat on your Fusion means draining some coolant, removing the thermostat housing, installing a new thermostat, then refilling and bleeding the cooling system. The thermostat controls coolant flow so the engine warms up correctly and does not overheat.

Difficulty Level: Intermediate | Estimated Time: 2-3 hours

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⚠️ Safety & Precautions

• ⚠️ Work only on a completely cold engine. Hot coolant can cause serious burns.
• ⚠️ Wear safety glasses and gloves because coolant is toxic and slippery.
• ⚠️ Keep coolant away from children and pets. Even small amounts can be dangerous.
• ⚠️ Do not remove the coolant reservoir cap while the engine is hot.
• ⚠️ Disconnecting the battery is not normally required for this repair, but keep tools away from the battery terminals.

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🔧 Required Tools

You'll need the following tools for this repair:

• 8mm socket
• 10mm socket
• 13mm socket
• 1/4-inch drive ratchet
• 3/8-inch drive ratchet
• 6-inch extension
• Flat-blade screwdriver
• Hose clamp pliers
• Plastic trim clip remover
• Torque wrench inch-pound range
• Coolant drain pan 2-gallon minimum
• Spill-free coolant funnel kit
• Shop towels
• Safety glasses
• Nitrile gloves
• Floor jack rated 2-ton minimum
• Jack stands rated 2-ton minimum
• Wheel chocks

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Engine thermostat - Qty: 1
• Thermostat housing seal - Qty: 1
• Motorcraft Orange-compatible coolant concentrate or premixed coolant - Qty: 1-2 gallons
• Distilled water - Qty: 1 gallon if using coolant concentrate
• Replacement hose clamps - Qty: As needed

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📋 Before You Begin

• Park your Fusion on level ground and let the engine cool fully, preferably overnight.
• Set the parking brake and place wheel chocks behind the rear wheels.
• If lifting the front, use a floor jack and support the car with jack stands. Never work under a car supported only by a jack.
• A spill-free funnel is a funnel that locks into the coolant reservoir and helps remove trapped air while refilling.
• A torque wrench tightens bolts to a specific force so plastic parts are not cracked.
• Set the cabin heater temperature to full hot before starting the engine during the refill/bleed process.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove Pressure From The Cooling System

• Make sure the engine is cold to the touch.
• Use your hand to slowly loosen the coolant reservoir cap.
• If you hear pressure escaping, stop and let it finish before removing the cap fully.
• Cold engine only.

Step 2: Raise And Secure The Front

• Use wheel chocks behind the rear wheels.
• Use a floor jack rated 2-ton minimum to lift the front of your Fusion at the front jacking point.
• Place jack stands rated 2-ton minimum under the proper front support points.
• Gently lower the car onto the jack stands and confirm it is stable.

Step 3: Remove The Lower Splash Shield

• Use an 8mm socket and 1/4-inch drive ratchet to remove the splash shield screws.
• Use a plastic trim clip remover to release any push clips.
• Set the splash shield and hardware aside in order.

Step 4: Drain Enough Coolant

• Place a coolant drain pan 2-gallon minimum under the radiator drain area.
• Use a flat-blade screwdriver to carefully open the radiator drain petcock if equipped and accessible.
• If the drain is not accessible, use hose clamp pliers to release the lower radiator hose clamp and gently move the hose enough to drain coolant.
• Drain about 1 gallon, or until the coolant level is below the thermostat housing.
• Close the radiator drain or reinstall the hose using hose clamp pliers.
• Catch every drop possible.

Step 5: Access The Thermostat Housing

• The thermostat housing is mounted on the engine where the lower coolant hose connects.
• Use hose clamp pliers to compress the clamp on the thermostat housing hose.
• Slide the clamp back on the hose.
• Use your hand to twist the hose gently to break it loose.
• If stuck, use a flat-blade screwdriver carefully at the hose edge only. Do not gouge the plastic housing.

Step 6: Remove The Thermostat Housing

• Place shop towels below the housing to catch leftover coolant.
• Use a 10mm socket, 6-inch extension, and 1/4-inch drive ratchet to remove the thermostat housing bolts.
• Pull the housing straight away from the engine.
• Remove the old thermostat and seal by hand.
• Note the thermostat orientation before removal so the new one installs the same way.

Step 7: Clean The Sealing Surface

• Use shop towels to wipe the engine sealing surface clean.
• Use your fingers to check for old seal material stuck to the surface.
• Do not use a metal scraper on aluminum or plastic sealing areas.
• The sealing surface is the flat area where the gasket seals coolant inside.

Step 8: Install The New Thermostat

• Install the new thermostat in the same orientation as the old one.
• Install the new thermostat housing seal by hand.
• Make sure the seal sits flat and is not twisted.
• Position the housing evenly against the engine.

Step 9: Tighten The Thermostat Housing Bolts

• Start all housing bolts by hand first to avoid cross-threading.
• Use a 10mm socket, 6-inch extension, and 1/4-inch drive ratchet to snug the bolts evenly.
• Use an inch-pound torque wrench with a 10mm socket to tighten the bolts evenly.
• Torque to 10 Nm (89 in-lbs)
• Do not overtighten. The housing can crack.

Step 10: Reconnect The Coolant Hose

• Push the coolant hose fully onto the thermostat housing neck by hand.
• Use hose clamp pliers to move the clamp back to its original position.
• Check that the clamp sits behind the raised bead on the housing neck.

Step 11: Refill The Cooling System

• Install a spill-free coolant funnel kit onto the coolant reservoir.
• Add Motorcraft Orange-compatible premixed coolant slowly to the reservoir.
• If using concentrate, mix coolant and distilled water 50/50 before filling.
• Fill until the coolant level reaches the MAX mark or stabilizes in the funnel.

Step 12: Bleed Air From The Cooling System

• Start the engine and leave the spill-free coolant funnel kit installed.
• Set the heater temperature to full hot and blower speed to low using the climate controls.
• Let the engine idle while watching the coolant level.
• Add coolant as the level drops.
• Watch for bubbles in the funnel. Bubbles mean trapped air is leaving the system.
• Let the engine reach normal operating temperature and confirm warm air comes from the vents.
• Use safety glasses and gloves while checking for leaks around the thermostat housing.

Step 13: Reinstall The Lower Splash Shield

• Turn the engine off and let it cool until safe to touch.
• Use a plastic trim clip remover to reinstall push clips if removed.
• Use an 8mm socket and 1/4-inch drive ratchet to reinstall splash shield screws.
• Tighten the splash shield screws snug only.

Step 14: Lower The Vehicle

• Use a floor jack rated 2-ton minimum to raise the front slightly off the jack stands.
• Remove the jack stands.
• Lower your Fusion slowly to the ground.
• Remove the wheel chocks.

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✅ After Repair

• Let the engine cool fully, then check the coolant level again and top off to the MAX mark if needed.
• Take a short test drive while watching the temperature gauge.
• After the drive, park and inspect the thermostat housing, hose connection, and lower radiator area for leaks.
• Recheck coolant level the next morning when the engine is cold.
• If the heater blows cold air, the temperature gauge rises, or coolant level keeps dropping, stop driving and re-bleed/check for leaks.
• Dispose of old coolant properly at a recycling or service facility. Do not pour it on the ground or into drains.

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💰 DIY vs Shop Cost

Shop Cost: $275-$500 (parts + labor)

DIY Cost: $45-$130 (parts only)

You Save: $230-$370 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-2.5 hours.

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🎯 Ready to get started?

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