🔧 Kona - Thermostat Replacement

On your Kona, the thermostat sits inside a thermostat housing/coolant outlet on the engine. Replacing it fixes issues like overheating, slow warm-up, or a thermostat housing leak, and it requires draining and refilling coolant to remove trapped air.

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

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⚠️ Safety & Precautions

• Never open the coolant reservoir cap on a hot engine; wait until fully cold.
• Support the vehicle on jack stands if you lift it; never rely on a floor jack alone.
• Coolant is toxic—wear gloves and safety glasses, and clean spills immediately.
• Keep coolant off belts and electrical connectors.
• Battery disconnect is recommended if you’ll remove the battery/air ducting near wiring.

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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 2-gallon)
• Funnel
• Spill-free coolant funnel kit (specialty)
• Trim clip removal tool
• 10mm socket
• 12mm socket
• 1/4" ratchet
• 3/8" ratchet
• 3" extension
• Torque wrench (inch-pound or low-range Nm)
• Pliers for hose clamps
• Flathead screwdriver
• Shop towels

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Thermostat (or thermostat housing/thermostat assembly) - Qty: 1
• Thermostat housing gasket or O-ring seal - Qty: 1
• Engine coolant (Hyundai/Kia long-life coolant, P-OAT type) - Qty: 1-2 gallons
• Distilled water - Qty: 1-2 gallons
• Replacement hose clamp - Qty: 1-2

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📋 Before You Begin

• Park on level ground, set the parking brake, and let the engine go fully cold.
• Set the cabin heat to HOT during bleeding later (this helps move coolant through the heater core).
• If you plan to remove the battery for access, use a 10mm socket to disconnect the negative terminal first and isolate it.
• Place a drain pan under the front of the vehicle before opening any hoses.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Confirm what you’re replacing

• Look at your new part: some Kona setups use a thermostat that comes as part of a housing/coolant outlet assembly.
• If yours is an assembly, you’ll swap the whole unit; if it’s thermostat-only, you’ll open the housing and replace the thermostat and seal.
• If unsure, match it to the part you remove.

Step 2: Raise the front (if needed for access)

• Use a floor jack (rated 3-ton minimum) to lift the front safely.
• Set the vehicle on jack stands (rated 3-ton minimum) and chock a rear wheel with wheel chocks.

Step 3: Remove the lower splash shield (if equipped)

• Use a trim clip removal tool for plastic clips and a 10mm socket for bolts.
• Set fasteners aside in a tray so none are lost.

Step 4: Drain the coolant

• Place the drain pan (at least 2-gallon) under the radiator area.
• Slowly loosen the coolant reservoir cap by hand to relieve any remaining pressure (engine must be cold).
• Drain coolant from the radiator drain (if accessible) or by removing the lower radiator hose using pliers for hose clamps.
• Use shop towels to catch spills.

Step 5: Remove the air intake ducting for access (typical)

• Use a flathead screwdriver to loosen intake hose clamps.
• Use a 10mm socket to remove any duct/airbox bolts if present.
• Move the ducting aside without yanking on sensors or wiring.

Step 6: Locate the thermostat housing/coolant outlet

• Follow the upper radiator hose to the engine side; it typically connects at or near the thermostat housing.
• Clean the area with shop towels so dirt can’t fall into the cooling system.

Step 7: Remove hoses and connectors at the housing

• Use pliers for hose clamps to slide spring clamps back, then twist the hose gently to break it loose.
• If an electrical connector is attached (sensor), release the lock tab by hand and unplug it (don’t pull on wires).

Step 8: Remove the thermostat housing

• Use a 12mm socket with a ratchet and extension to remove the housing bolts.
• Expect more coolant to spill—keep the drain pan under it.
• Remove the housing straight off to avoid damaging the sealing surface.

Step 9: Replace the thermostat and seal (thermostat-only path)

• Note the thermostat orientation before removal.
• Remove the thermostat and old seal by hand; do not reuse the seal.
• Install the new thermostat and new gasket/O-ring exactly the same way it came out.

Step 10: Install the new thermostat housing/assembly (assembly path)

• Make sure the new gasket/O-ring is seated correctly and not twisted.
• Set the assembly in place evenly by hand before installing bolts.

Step 11: Reinstall and torque the housing bolts

• Start all bolts by hand to avoid cross-threading.
• Tighten evenly using a 12mm socket.
• Use a torque wrench: Torque to 9.8–11.8 Nm (7–9 ft-lbs).

Step 12: Reconnect hoses and electrical connectors

• Reinstall hoses fully to their stops, then position clamps back in their original locations using pliers for hose clamps.
• Reconnect any electrical connector until it clicks.

Step 13: Reinstall intake ducting and splash shield

• Reinstall intake parts using a flathead screwdriver for clamps and 10mm socket for bolts.
• Reinstall the splash shield using a 10mm socket and trim clip removal tool as needed.

Step 14: Refill coolant and bleed air

• Mix coolant with distilled water as required by the coolant you purchased (many long-life coolants come premixed—check the label).
• Install a spill-free coolant funnel kit (specialty) on the reservoir/filled neck and fill slowly.
• Start the engine and let it idle with the heater set to HOT.
• As the engine warms up, add coolant as the level drops and watch for bubbles.
• When the radiator fan cycles and the heater blows hot, the thermostat is opening and air should be purging.
• Shut the engine off, let it cool fully, then recheck and top off to the MAX line using a funnel.
• Keep coolant above the funnel bottom.

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✅ After Repair

• Check carefully for leaks around the housing and hose connections with the engine idling.
• Verify normal temperature gauge behavior on a short test drive.
• After the next full cool-down, recheck the coolant level and top off if needed.
• If the check engine light comes on or it still overheats, stop and recheck for trapped air or a loose clamp.

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💰 DIY vs Shop Cost

Shop Cost: $350-$750 (parts + labor)

DIY Cost: $60-$220 (parts only)

You Save: $130-$690 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?

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