🔧 Thermostat - Replacement

This job means draining enough coolant to open the cooling system, removing the thermostat housing, and installing a new thermostat and seal. On your XC90, the thermostat sits on the front of the engine coolant circuit and coolant bleeding matters after the repair.

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.
• Use eye protection and gloves. Coolant can spray when the system is opened.
• Keep coolant away from pets and children; it is toxic.
• Battery disconnect is not required for this repair, but do not let tools bridge battery terminals.
• Make sure the car is securely supported if you raise the front for access.
• Open the cap only when the engine is cold.

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🔧 Required Tools

You'll need the following tools for this repair:

• 8mm socket
• 10mm socket
• Torx T25 screwdriver
• Torx T30 screwdriver
• Ratchet
• Extension bar
• Small pick tool
• Drain pan
• Funnel
• Floor jack (rated 3-ton minimum)
• Jack stands
• Safety glasses
• Nitrile gloves
• Torque wrench
• Plastic trim tool

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Thermostat assembly - Qty: 1
• Thermostat housing gasket or seal - Qty: 1
• Engine coolant - Qty: 1-2 gallons
• Cooling system bleed cap seal - Qty: 1

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📋 Before You Begin

• Park on level ground and let the engine go fully cold.
• Set the parking brake and open the hood.
• Have a drain pan ready before loosening any coolant connection.
• Keep the new thermostat within reach.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Drain the coolant

• Place a drain pan under the radiator drain point or lower coolant hose area.
• Use the appropriate tool to open the drain point or loosen the lower hose clamp.
• Drain enough coolant to get the level below the thermostat housing.
• Close the drain point after draining.

Step 2: Remove intake and access parts

• Use the 8mm socket, 10mm socket, and Torx T25 screwdriver to remove any intake ducting, covers, or brackets blocking access.
• Label connectors or hoses if they must be removed.
• Take a quick photo before removing anything.

Step 3: Disconnect the thermostat housing connections

• Use a small pick tool if needed to release hose clips carefully.
• Disconnect the coolant hose from the thermostat housing.
• Move the hose aside and catch any remaining coolant in the drain pan.

Step 4: Remove the thermostat housing

• Use the Torx T30 screwdriver and ratchet with extension to remove the thermostat housing bolts.
• Lift the housing away from the engine.
• Remove the old gasket or seal.
• Torque on installation: 10 Nm (7 ft-lbs)

Step 5: Install the new thermostat

• Compare the new thermostat assembly to the old one before installing.
• Install the new gasket or seal in the correct groove.
• Position the thermostat housing onto the engine carefully so the seal does not pinch.
• Install the bolts finger-tight first, then tighten evenly with the torque wrench.
• Torque to 10 Nm (7 ft-lbs)

Step 6: Reconnect hoses and reinstall removed parts

• Reconnect the coolant hose and secure the clip or clamp.
• Reinstall all intake pieces, covers, and brackets using the 8mm socket, 10mm socket, and Torx T25 screwdriver.
• Make sure every connector and clamp is fully seated.

Step 7: Refill and bleed the cooling system

• Use a funnel to refill with the correct coolant mix.
• Fill slowly to reduce trapped air.
• Start the engine and let it idle with the heater set to warm.
• Watch for bubbles and top off as the coolant level drops.
• Install the cap once the level stabilizes.
• Air pockets cause overheating.

Step 8: Check for leaks and verify operation

• Inspect the thermostat housing, hose connections, and drain point for leaks.
• Bring the engine to operating temperature.
• Confirm the cabin heat works and the temperature gauge stays normal.

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✅ After Repair

• Recheck coolant level after the first drive and again after the engine cools.
• Look for warning messages on the dash.
• If the engine overheats or the heater blows cold, stop and re-bleed the system.
• Inspect again the next day for any seepage around the housing.

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💰 DIY vs Shop Cost

Shop Cost: $450-$850 (parts + labor)

DIY Cost: $90-$220 (parts only)

You Save: $360-$630 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2-3 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.