🔧 Expedition - Thermostat Replacement

Replacing the thermostat on your Expedition requires draining some engine coolant, removing the thermostat housing at the front of the 3.5L EcoBoost engine, installing a new thermostat/seal, and refilling the cooling system. A stuck thermostat can cause overheating, slow warm-up, poor heater performance, or temperature warning messages.

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

---

⚠️ Safety & Precautions

• ⚠️ Work only on a completely cool engine. Hot coolant is pressurized and can cause severe burns.
• ⚠️ Do not remove the coolant pressure cap while the engine is hot.
• ⚠️ Support the Expedition securely with jack stands if you raise the front. Never rely on a jack alone.
• ⚠️ Keep coolant away from pets and children. It is toxic and has a sweet smell.
• ⚠️ Disconnecting the battery is not normally required for this repair, but keep tools away from the battery terminals and radiator fan area.
• ⚠️ The electric cooling fans can run unexpectedly. Keep fingers and tools clear of the fan blades.

---

🔧 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
• Torque wrench inch-pound range
• Torque wrench foot-pound range
• Flat-blade screwdriver
• Hose clamp pliers
• Plastic trim clip remover
• Drain pan 2-gallon minimum
• Long-neck funnel
• Cooling system spill-free funnel kit
• Floor jack rated 3-ton minimum
• Jack stands rated 3-ton minimum
• Wheel chocks
• Shop towels
• Nitrile gloves
• Safety glasses

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Engine coolant thermostat - Qty: 1
• Thermostat seal/O-ring - Qty: 1
• Orange or yellow Ford-compatible prediluted coolant - Qty: 1-2 gallons
• Thermostat housing assembly - Qty: 1, if cracked or warped
• Radiator drain plug seal - Qty: 1, if damaged

---

📋 Before You Begin

• 🚗 Park your Expedition on level ground, shift to Park, and set the parking brake.
• 🧊 Let the engine cool fully, preferably overnight.
• 🧱 Place wheel chocks behind the rear wheels.
• 📱 No infotainment menu steps are required for this thermostat replacement.
• 🔍 A spill-free funnel is a funnel that locks onto the coolant reservoir so air bubbles can safely escape while you refill the system.
• 🔧 Hose clamp pliers are pliers shaped to squeeze spring-style hose clamps without damaging the hose.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Raise and secure the front

• Use a floor jack rated 3-ton minimum to raise the front of your Expedition only if you need more access underneath.
• Place jack stands rated 3-ton minimum under the proper front support points.
• Use wheel chocks at the rear wheels before going under the vehicle.
• Never work under a jack alone.

Step 2: Remove the lower splash shield

• Put on safety glasses and nitrile gloves.
• Use a 7mm or 8mm socket if equipped fasteners are present; if your shield uses push clips, use a plastic trim clip remover.
• Remove the front lower splash shield and set it aside.
• If your Expedition has different shield fasteners, match the socket to the fastener head and remove carefully.

Step 3: Relieve cooling system pressure

• Make sure the engine is cold.
• Slowly loosen the coolant reservoir pressure cap by hand.
• If you hear pressure escaping, stop and wait until it finishes before removing the cap fully.

Step 4: Drain some coolant

• Place a drain pan 2-gallon minimum under the radiator drain area.
• Use a flat-blade screwdriver or your hand, depending on the drain plug style, to open the radiator drain plug.
• Drain about 1 gallon of coolant, or enough so the level is below the thermostat housing.
• Close the radiator drain plug by hand or with the flat-blade screwdriver. Do not overtighten plastic drain plugs.
• Catch every drop you can.

Step 5: Locate the thermostat housing

• Stand at the front of your Expedition and follow the large upper radiator hose toward the engine.
• The hose connects to the thermostat housing at the front of the engine area.
• Use shop towels around the housing area to catch leftover coolant.

Step 6: Remove the intake duct if it blocks access

• Use an 8mm socket or flat-blade screwdriver to loosen the air intake tube clamps if they block your hand access.
• Disconnect any attached breather tube by hand.
• Move the intake duct aside carefully.

Step 7: Disconnect the radiator hose from the thermostat housing

• Use hose clamp pliers to squeeze the spring clamp on the upper radiator hose.
• Slide the clamp back onto the hose.
• Twist the hose gently by hand to break it loose, then pull it off the thermostat housing.
• If the hose is stuck, use a flat-blade screwdriver very gently at the hose edge. Do not cut or gouge the hose.

Step 8: Remove the thermostat housing bolts

• Use a 10mm socket, 1/4-inch drive ratchet, and 6-inch extension to remove the thermostat housing bolts.
• Remove the housing straight off the engine.
• Note the thermostat position before removing it.
• Some coolant may spill; use shop towels and keep the drain pan underneath.

Step 9: Remove the old thermostat and seal

• Pull the old thermostat out by hand.
• Remove the old thermostat seal/O-ring by hand or carefully with a flat-blade screwdriver.
• Do not scratch the aluminum sealing surface.
• Clean surfaces seal best.

Step 10: Clean and inspect the housing

• Use shop towels to wipe the thermostat housing and engine sealing surface clean.
• Inspect the plastic housing for cracks, warping, or damaged hose necks.
• Replace the thermostat housing assembly if it is cracked or distorted.

Step 11: Install the new thermostat

• Install the new thermostat seal/O-ring onto the new engine coolant thermostat if it is not pre-installed.
• Place the thermostat into the housing/engine in the same orientation as the old one.
• Make sure the seal sits flat and is not pinched.

Step 12: Reinstall the thermostat housing

• Position the housing squarely against the engine.
• Start all bolts by hand first to avoid cross-threading.
• Use a 10mm socket, 1/4-inch drive ratchet, and 6-inch extension to snug the bolts evenly.
• Use a torque wrench inch-pound range to tighten the thermostat housing bolts evenly to Torque to 10 Nm (89 in-lbs).

Step 13: Reconnect the radiator hose

• Push the upper radiator hose fully onto the thermostat housing neck by hand.
• Use hose clamp pliers to move the spring clamp back to its original position.
• Make sure the clamp sits behind the raised bead on the hose neck.

Step 14: Reinstall the intake duct

• Place the intake duct back into position.
• Reconnect any breather tube by hand.
• Use an 8mm socket or flat-blade screwdriver to tighten the intake tube clamps snugly.

Step 15: Refill the cooling system

• Install the cooling system spill-free funnel kit onto the coolant reservoir.
• Use a long-neck funnel if you do not have a spill-free kit, but the spill-free kit is strongly recommended.
• Add Ford-compatible prediluted coolant until the coolant reservoir reaches the correct cold-fill level.
• Use only coolant that matches the required Ford specification for your Expedition. Do not mix random coolant types.

Step 16: Bleed air from the cooling system

• Leave the spill-free funnel installed.
• Start the engine and let it idle.
• Set the cabin heat to maximum temperature and low fan speed using the climate controls.
• Watch the coolant level in the funnel and add coolant as the level drops.
• Let the engine warm up until the thermostat opens and the upper radiator hose becomes hot.
• Use safety glasses and keep hands away from belts and fans while checking for leaks.

Step 17: Check for leaks and finish filling

• Use a flashlight if available to inspect around the thermostat housing, hose connection, and drain plug.
• If no leaks are present, shut the engine off.
• Allow the engine to cool fully.
• Remove the spill-free funnel and install the coolant reservoir pressure cap by hand.
• Top off the coolant reservoir to the cold-fill mark using the long-neck funnel.

Step 18: Reinstall the lower splash shield

• Raise the splash shield into position by hand.
• Use the 8mm socket or plastic trim clip remover as needed to reinstall the fasteners or clips.
• Use the floor jack rated 3-ton minimum to lift slightly, remove the jack stands rated 3-ton minimum, and lower the Expedition carefully.

---

✅ After Repair

• ✅ Drive your Expedition for 10-15 minutes while watching the temperature gauge.
• ✅ Confirm the heater blows warm air at idle and while driving.
• ✅ Let the engine cool completely, then recheck the coolant reservoir level and top off if needed.
• ✅ Inspect the thermostat housing area again for dried coolant trails or fresh leaks.
• ✅ If the temperature warning returns, stop driving and recheck coolant level, trapped air, and thermostat housing sealing.
• ✅ Dispose of used coolant at a recycling or service facility. Do not pour it on the ground or into drains.

---

💰 DIY vs Shop Cost

Shop Cost: $350-$650 (parts + labor)

DIY Cost: $45-$180 (parts only)

You Save: $250-$500 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.

---

🎯 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.