🔧 Thermostat - Replacement

Your F-150’s thermostat controls engine coolant flow. If it sticks open or closed, you can get slow warm-up, overheating, poor heat, or temperature swings. This job is mostly a coolant-drain and hose-removal task, then installing the new thermostat and refilling the cooling system.

Difficulty Level: Intermediate | Estimated Time: 2-4 hours

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⚠️ Safety & Precautions

• Work only on a completely cold engine. Hot coolant can cause severe burns.
• Disconnect the negative battery cable before working near the accessory drive or cooling fan area.
• Keep coolant away from children and pets. Used coolant is toxic.
• Use jack stands if you raise the truck. Never rely on a jack alone.
• Dispose of old coolant properly according to local rules.

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🔧 Required Tools

You'll need the following tools for this repair:

• Metric socket set
• 1/4-inch drive ratchet
• 3/8-inch drive ratchet
• 10mm socket
• 8mm socket
• Extensions
• Flat-blade screwdriver
• Pliers
• Hose clamp pliers (specialty)
• Drain pan
• Funnel
• Coolant vacuum filler (specialty)
• Pick tool
• Torque wrench
• Shop towels
• Safety glasses
• Nitrile gloves
• Jack and jack stands

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Thermostat - Qty: 1
• Thermostat housing gasket - Qty: 1
• Engine coolant, orange OAT - Qty: 1-2 gallons
• Hose clamps - Qty: as needed

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📋 Before You Begin

• Park on level ground and set the parking brake.
• Let the engine cool fully.
• Relieve any pressure slowly by loosening the coolant reservoir cap only when cold.
• Have a drain pan ready before opening any coolant hose or drain.
• If your truck has skid plates or splash shields blocking access, remove them first.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Disconnect power and gain access

• Use a 10mm socket to disconnect the negative battery cable.
• If needed, use a 10mm socket and 3/8-inch ratchet to remove the engine cover and any intake ducting blocking the thermostat area.
• Remove any splash shield or air inlet parts that block your view.

Step 2: Drain enough coolant

• Place a drain pan under the radiator area.
• Open the radiator drain or lower hose connection enough to lower the coolant level below the thermostat housing.
• Use pliers or hose clamp pliers (specialty) to release the hose clamp.
• Drain only what you need.

Step 3: Remove the thermostat housing

• Locate the thermostat housing on the coolant outlet near the engine.
• Use an 8mm socket or 10mm socket to remove the housing bolts, depending on your fastener style.
• Carefully twist the housing loose if it sticks. Do not pry hard on the sealing surface.
• Use a pick tool to remove the old gasket if it remains stuck.

Step 4: Replace the thermostat

• Remove the old thermostat from the housing or engine outlet.
• Install the new thermostat in the same orientation as the old one.
• Install the new thermostat housing gasket.
• Make sure the sealing surfaces are clean and dry.

Step 5: Reinstall the housing

• Set the housing back in place by hand first.
• Use a 10mm socket and torque wrench to tighten the bolts evenly.
• Torque to 10 Nm (89 in-lbs).
• Reconnect the coolant hose and secure the clamp with pliers or hose clamp pliers (specialty).

Step 6: Refill and bleed the cooling system

• Reinstall any drain plugs or hoses you removed.
• Refill with the correct orange coolant using a funnel or coolant vacuum filler (specialty).
• Fill the reservoir to the proper mark.
• Start the engine and let it idle with the heater set to HOT.
• Watch the coolant level and top off as air burps out.
• Do not rev a cold engine.

Step 7: Reassemble and verify

• Reinstall the intake ducting, covers, and splash shields.
• Reconnect the negative battery cable with a 10mm socket.
• Check for leaks at the housing and hose connections.
• Confirm the temperature gauge reaches normal and stays steady.

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✅ After Repair

• Let the engine reach full operating temperature.
• Check heater output inside the cab.
• Recheck coolant level after a full cool-down cycle.
• Inspect for leaks again the next day.
• If the temperature still runs hot, the system may need further diagnosis for trapped air, a water pump issue, or cooling fan concerns.

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💰 DIY vs Shop Cost

Shop Cost: $350-$700 (parts + labor)

DIY Cost: $60-$180 (parts only)

You Save: $290-$520 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2-4 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.