🔧 TLX - Thermostat Replacement

Your TLX’s thermostat controls coolant flow to help the engine reach (and stay at) the correct operating temperature. Replacing it means draining some coolant, swapping the thermostat and its seal, then refilling and bleeding air from the cooling system.

Difficulty Level: Intermediate | Estimated Time: 1.5-3.0 hours

Assumption: 2.4L uses a water outlet-mounted thermostat at the upper radiator hose.

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⚠️ Safety & Precautions

• ⚠️ Never open the radiator cap on a hot engine; hot coolant can spray out.
• ⚠️ Support the car with jack stands before working underneath.
• ⚠️ Keep coolant off belts and electrical connectors; wipe spills immediately.
• ⚠️ Coolant is toxic to pets and people; drain into a pan and seal containers.
• ⚠️ Battery disconnect is recommended if you’ll be working near the radiator fan.

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🔧 Required Tools

You'll need the following tools for this repair:

• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• Safety glasses
• Nitrile gloves
• Drain pan (at least 10-quart)
• Funnel with long neck
• Shop towels
• 10mm socket
• 12mm socket
• 1/4" ratchet
• 3/8" ratchet
• 6" extension
• Torque wrench (3/8" drive)
• Hose clamp pliers
• Pick tool
• Flathead screwdriver
• Trim clip remover (specialty)

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Engine thermostat - Qty: 1
• Thermostat gasket / O-ring seal - Qty: 1
• Honda/Acura Type 2 coolant (premixed 50/50) - Qty: 2 gallons
• Upper radiator hose clamp - Qty: 1

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📋 Before You Begin

• 🧰 Park on level ground, set the parking brake, and chock the rear wheels.
• 🧊 Let the engine cool completely (best: sit overnight).
• 🔋 Disconnect the negative battery terminal using a 10mm socket.
• 🛗 Raise the front with a floor jack and place on jack stands at the factory lift points.
• 🧠 If you’re new to a torque wrench: it’s a tool that clicks when you reach the correct tightness.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the lower splash shield (if equipped)

• Use a trim clip remover (specialty) and 10mm socket to remove the clips/bolts holding the lower engine cover.
• Set the clips/bolts aside in a small tray so you don’t lose them.

Step 2: Drain coolant from the radiator

• Place a drain pan (at least 10-quart) under the radiator drain area.
• Slowly remove the radiator cap (only if the engine is fully cool).
• Open the radiator drain cock using a flathead screwdriver if needed.
• Let coolant drain until the flow slows to a drip.
• Keep coolant off the serpentine belt.

Step 3: Remove the air intake ducting for access

• Use a flathead screwdriver to loosen the intake hose clamps.
• Use a 10mm socket to remove any air box/duct mounting bolts.
• Lift the ducting out carefully and place it aside.

Step 4: Locate the thermostat housing (water outlet)

• Follow the upper radiator hose to where it meets the engine; that connection is typically the thermostat housing.
• Clean the area with shop towels so dirt won’t fall inside when opened.

Step 5: Remove the upper radiator hose from the housing

• Use hose clamp pliers to compress the hose clamp and slide it back on the hose.
• Twist the hose gently to break it free, then pull it off.
• If it’s stuck, use a pick tool to gently lift the hose edge to let air in (don’t gouge the hose neck).

Step 6: Remove the thermostat housing

• Place shop towels under the housing to catch remaining coolant.
• Use a 10mm socket (and 6" extension if needed) to remove the thermostat housing bolts.
• Pull the housing straight off; some coolant will spill into the drain pan.

Step 7: Replace the thermostat and seal

• Remove the old thermostat and the old gasket/O-ring by hand.
• Wipe the mating surfaces clean using shop towels. Do not scrape aggressively.
• Install the new thermostat in the same orientation as the old one.
• Install the new gasket/O-ring (do not reuse the old seal).
• Wrong orientation can cause overheating.

Step 8: Reinstall the thermostat housing

• Reinstall the housing and start bolts by hand to avoid cross-threading.
• Tighten evenly using a 10mm socket.
• Final tighten with a torque wrench (3/8" drive): Torque to 12 Nm (9 ft-lbs).

Step 9: Reconnect the upper radiator hose

• Slide the hose fully onto the housing neck.
• Use hose clamp pliers to position the clamp back in its original spot.

Step 10: Refill coolant and bleed air

• Close the radiator drain cock by hand (snug only) using a flathead screwdriver if needed.
• Fill the radiator slowly using a funnel with long neck and Honda/Acura Type 2 coolant (premixed 50/50).
• Fill the coolant reservoir to the MAX line.
• Reconnect the negative battery terminal using a 10mm socket.
• Start the engine and set cabin heat to HOT (high temp), fan on low.
• Let the engine idle until warm; watch the temp gauge and check for leaks.
• When the radiator fan cycles on and off at least once, shut the engine off and let it cool.
• Top off the radiator and reservoir again using the funnel with long neck.

Step 11: Reinstall covers and intake parts

• Reinstall the air intake ducting using a 10mm socket and tighten clamps with a flathead screwdriver.
• Reinstall the lower splash shield using a trim clip remover (specialty) and 10mm socket.

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✅ After Repair

• 🔍 With the engine running, inspect the thermostat housing and hose connection for leaks.
• 🌡️ Test drive 10–15 minutes and confirm normal temperature (no overheating).
• 🧊 After a full cool-down, recheck coolant level in the reservoir and top off if needed.
• 🧼 Properly dispose of used coolant at a recycling center or parts store.

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💰 DIY vs Shop Cost

Shop Cost: $300-$650 (parts + labor)

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

You Save: $170-$605 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?

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.