🔧 Challenger - Thermostat Replacement

The thermostat controls coolant flow so your A4—sorry—your Challenger can warm up correctly and stay at the right operating temperature. Replacing it usually involves draining some coolant, removing the thermostat housing, swapping the thermostat/seal, then refilling and bleeding air from the cooling system.

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

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⚠️ Safety & Precautions

• ⚠️ Never open the coolant cap on a hot engine; pressurized coolant can burn you.
• ⚠️ Support the car with jack stands if you raise it—never rely on a floor jack alone.
• ⚠️ Keep coolant off belts and electrical connectors; wipe spills immediately.
• ⚠️ Coolant is toxic to pets and people—catch all fluid and dispose properly.
• 🔋 Battery disconnect is not required, but keep tools clear of the radiator fan area.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• Drain pan (at least 3-gallon)
• Funnel
• 8mm socket
• 10mm socket
• 1/4" drive ratchet
• 3/8" drive ratchet
• 3" extension
• Hose clamp pliers
• Trim clip removal tool
• Torque wrench (in-lb)
• Shop towels

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Engine thermostat with seal/gasket - Qty: 1
• Engine coolant (OAT, purple) 50/50 premix - Qty: 2-3 gallons
• Worm-gear hose clamp assortment - Qty: 1 (only if factory clamp is damaged)

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📋 Before You Begin

• Park on level ground, set the parking brake, and place wheel chocks behind the rear tires.
• Let the engine cool completely (best: sit overnight).
• Set the cabin HVAC to Heat (this helps coolant circulate through the heater core during bleeding).
• If you raise the front, lift with a floor jack and support with jack stands under the correct front support points.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Relieve cooling system pressure (cold engine only)

• Place shop towels around the coolant fill point.
• Slowly loosen the coolant cap to the first stop to release any remaining pressure, then remove it fully.
• If it hisses, wait and try again.

Step 2: Drain coolant to below thermostat level

• Position a drain pan (at least 3-gallon) under the radiator drain area.
• If access is tight, remove any lower splash shield fasteners using a trim clip removal tool and 8mm socket (as equipped).
• Drain enough coolant so the level is below the thermostat housing (you do not always need to drain the entire system).

Step 3: Remove the air intake ducting (for working room)

• Loosen the intake tube clamps using an 8mm socket.
• Disconnect any attached breather tube(s) by hand and lift the intake tube/air duct out.
• Take a quick photo before unplugging hoses.

Step 4: Remove the radiator hose from the thermostat housing

• Place the drain pan directly under the thermostat housing area to catch spills.
• Use hose clamp pliers to compress the spring clamp and slide it back on the hose.
• Twist the hose gently to break it free, then pull it off. Use shop towels to control the spill.

Step 5: Remove the thermostat housing

• Remove the thermostat housing bolts using a 10mm socket, 1/4" drive ratchet, and 3" extension.
• Pull the housing straight off. Note the thermostat orientation as it comes out.
• Remove the old thermostat and seal/gasket.

Step 6: Clean the sealing surfaces

• Wipe the engine-side sealing surface and housing sealing surface using shop towels.
• Do not gouge the aluminum surface. Remove any stuck gasket material carefully by hand.

Step 7: Install the new thermostat and reinstall the housing

• Install the new thermostat with its seal/gasket seated correctly.
• Position the housing and start all bolts by hand to avoid cross-threading.
• Tighten housing bolts evenly using a 10mm socket.
• Final tighten with a torque wrench (in-lb): Torque to 105 in-lb (12 Nm).

Step 8: Reinstall the radiator hose and air intake

• Push the hose fully onto the thermostat housing neck.
• Use hose clamp pliers to return the clamp to its original position.
• Reinstall the intake ducting and tighten clamps using an 8mm socket.
• Reinstall any splash shields/fasteners removed using a trim clip removal tool and 8mm socket.

Step 9: Refill coolant

• Use a funnel to refill with OAT, purple 50/50 premix until the reservoir reaches the correct level.
• Leave the cap off for initial air purge.

Step 10: Bleed air and verify thermostat operation

• Start the engine and let it idle. Watch the coolant level and add as needed using the funnel.
• Set cabin heat to hot and fan to medium. Confirm you get steady warm air (a good sign coolant is circulating).
• As the engine warms, the upper hose should go from cool to hot when the thermostat opens.
• Once bubbles stop and level stabilizes, install the coolant cap.
• Shut the engine off, let it cool, then recheck level and top off as needed.
• Do not overfill the reservoir.

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✅ After Repair

• Check for leaks around the thermostat housing and hose connection with the engine running and again after a short drive.
• Verify the temperature gauge behaves normally (no overheating, no staying unusually cold).
• After 1–2 heat cycles (full warm-up then full cool-down), recheck coolant level and top off if needed.
• If you get overheating, no cabin heat, or gurgling sounds, shut it down and re-bleed air.

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💰 DIY vs Shop Cost

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

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

You Save: $170-$590 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-3.0 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.