🔧 Thermostat - Replacement

Your Explorer uses a coolant thermostat housed at the engine coolant outlet. Replacing it means draining some coolant, removing the housing, swapping the thermostat and seal, then refilling and bleeding the cooling system so the engine can regulate temperature correctly.

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

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⚠️ Safety & Precautions

• Work only on a completely cool engine. Hot coolant can cause serious burns.
• Keep pets and children away. Engine coolant is toxic.
• Use jack stands if you raise the vehicle. Never rely on a jack alone.
• Have a drain pan ready before opening the cooling system.
• Disconnect the negative battery cable if you will be working near the starter or wiring. It is not always required for this job, but it can help prevent accidents.

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🔧 Required Tools

You'll need the following tools for this repair:

• Metric socket set
• 8mm socket
• 10mm socket
• Ratchet
• Short extension
• Torque wrench
• Pliers
• Flat-blade screwdriver
• Drain pan
• Funnel
• Catch bottle or clean container
• Shop towels
• Safety glasses
• Nitrile gloves
• Jack and jack stands (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 seal - Qty: 1
• Engine coolant - Qty: 1 drain-and-refill quantity
• Distilled water - Qty: 1 if mixing coolant concentrate

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📋 Before You Begin

• Park on level ground and set the parking brake.
• Let the engine cool fully before touching the cooling system.
• Open the hood and remove the engine cover if equipped.
• Place a drain pan under the radiator drain area before opening the system.
• Tip: Take a photo of hose routing before removing anything.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Drain coolant to a safe level

• Use a drain pan under the radiator.
• Open the radiator drain or remove the lower hose enough to lower the coolant level below the thermostat housing.
• Only drain what you need so the job stays cleaner.
• Tip: Open the degas bottle cap slowly after cooling.

Step 2: Remove intake ducting and access parts

• Use an 8mm socket and ratchet to remove the air intake duct or air box pieces blocking access.
• Move hoses or wiring clips aside carefully.
• If a clamp is in the way, use pliers or a flat-blade screwdriver to release it.

Step 3: Disconnect the thermostat housing connections

• Use pliers to release spring clamps, if equipped.
• Pull the coolant hoses off the thermostat housing.
• Expect some coolant spill. Keep the drain pan in place.

Step 4: Remove the thermostat housing

• Use a 10mm socket, ratchet, and short extension to remove the housing bolts.
• Lift the housing straight off.
• Remove the old thermostat and gasket or seal.
• Clean the sealing surface with a shop towel. Do not scratch the aluminum.

Step 5: Install the new thermostat

• Install the new thermostat in the same orientation as the old one.
• Install the new gasket or seal.
• Set the housing back in place by hand first.
• Use the 10mm socket to snug the bolts evenly.
• Torque to 10 Nm (89 in-lbs).

Step 6: Reconnect hoses and intake parts

• Push the coolant hoses back onto the housing.
• Use pliers to move spring clamps back into position.
• Reinstall the intake ducting and tighten fasteners with the 8mm socket.
• Make sure every hose and clamp is fully seated.

Step 7: Refill and bleed the cooling system

• Use a funnel to refill with the correct coolant mixture.
• Fill the degas bottle to the proper mark.
• Start the engine with the cap on loosely if needed, and let it idle.
• Turn the heater to full hot and fan on low.
• Watch for bubbles and top off as the level drops.
• Install the cap when the level stabilizes.

Step 8: Check for leaks and proper operation

• Use a flashlight to inspect the thermostat housing, hose connections, and drain area.
• Let the engine reach operating temperature.
• Confirm the cabin heater gets warm and the temperature gauge stays normal.

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✅ After Repair

• Recheck coolant level after the first drive and again when the engine is cold.
• Look for dried coolant residue around the housing after a few heat cycles.
• If the check engine light was on before, clear codes and verify they do not return.
• Watch for overheating, fluctuating temperature, or a no-heat condition.

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💰 DIY vs Shop Cost

Shop Cost: $280-$520 (parts + labor)

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

You Save: $235-$390 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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