🔧 Accent - Thermostat Replacement

The thermostat controls engine temperature by opening and closing coolant flow to the radiator. If it sticks open you’ll run cool (poor heat, low MPG), and if it sticks closed you’ll overheat. On your Accent, the thermostat sits in the thermostat housing where the upper radiator hose connects to the engine.

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

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⚠️ Safety & Precautions

• ⚠️ Only work on a fully cool engine; hot coolant can cause severe burns.
• ⚠️ Support the car with jack stands on solid, level ground if you raise it.
• ⚠️ Keep coolant off belts and electrical connectors; wipe spills immediately.
• ⚠️ Dispose of used coolant properly; it’s toxic to people and pets.
• 🔋 Battery disconnect is not required for this job.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Drain pan (at least 2-gallon)
• Floor jack (rated 2-ton minimum)
• Jack stands (rated 2-ton minimum)
• Wheel chocks
• 10mm socket
• 12mm socket
• 3/8" drive ratchet
• 3/8" drive extension (3"-6")
• Torque wrench (inch-pound or low-range Nm)
• Flathead screwdriver
• Hose clamp pliers
• Trim clip remover
• Funnel
• Shop towels
• Plastic scraper

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Engine thermostat - Qty: 1
• Thermostat housing gasket or O-ring - Qty: 1
• Hyundai-compatible long-life coolant (pre-mixed 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 a rear wheel.
• 🧊 Let the engine cool completely (radiator hoses should feel cool).
• 🌡️ Set the cabin heat to full HOT later during bleeding (this opens the heater core to help purge air).
• 🧼 Lay shop towels under the thermostat housing area to catch spills.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Raise the front (if you need access underneath)

• Use floor jack to lift the front at the proper jacking point.
• Set the vehicle down on jack stands and keep wheel chocks in place.

Step 2: Remove the lower splash shield (if equipped)

• Use a trim clip remover and 10mm socket to remove the clips/bolts.
• Set the shield aside where it won’t get stepped on.

Step 3: Drain the coolant

• Place a drain pan (at least 2-gallon) under the radiator drain.
• Slowly loosen the radiator cap (only if fully cool) by hand to relieve any leftover pressure.
• Open the radiator drain using a flathead screwdriver if needed.
• Drain enough to drop level below the thermostat.

Step 4: Clear access to the thermostat housing

• Locate the upper radiator hose; follow it to where it meets the engine (thermostat housing).
• If the intake duct blocks access, loosen clamps with a flathead screwdriver and remove the duct by hand.

Step 5: Remove the upper radiator hose from the housing

• Use hose clamp pliers to compress the clamp and slide it back on the hose.
• Twist the hose gently to break it loose, then pull it off.
• Don’t pry hard on plastic fittings.

Step 6: Remove the thermostat housing

• Remove the housing bolts using a 10mm socket, 3/8" drive ratchet, and 3/8" drive extension.
• Pull the housing straight off and catch any remaining coolant in the drain pan.

Step 7: Replace the thermostat and seal

• Remove the old thermostat by hand and note its orientation.
• Clean the mating surfaces with a plastic scraper and shop towels.
• Install the new thermostat in the same orientation (the small “jiggle valve”/bleed pin, if present, should point upward).
• Install a new thermostat housing gasket or O-ring (do not reuse the old seal).

Step 8: Reinstall the thermostat housing

• Start all housing bolts by hand to avoid cross-threading.
• Tighten evenly with a 10mm socket.
• Final tighten with a torque wrench: Torque to 10 Nm (89 in-lbs).

Step 9: Reinstall the upper radiator hose

• Push the hose fully onto the housing by hand.
• Reposition the clamp using hose clamp pliers.
• If the clamp is weak or rusted, replace it with a new upper radiator hose clamp.

Step 10: Reinstall intake duct and splash shield

• Reinstall the intake duct and tighten clamps with a flathead screwdriver.
• Reinstall the splash shield using the 10mm socket and trim clip remover.

Step 11: Refill coolant

• Make sure the radiator drain is closed (snug, not over-tightened).
• Use a funnel to fill the radiator/expansion tank with Hyundai-compatible long-life coolant (pre-mixed 50/50).
• Fill the reservoir to the “FULL” line.

Step 12: Bleed air from the cooling system

• Start the engine and let it idle.
• Set the heater to HOT and the fan to low/medium.
• As the engine warms up, watch the coolant level and add as needed using the funnel.
• Once the thermostat opens, the upper hose will get hot and coolant level may drop—top off again.
• Shut the engine off, let it cool, then recheck and adjust the reservoir level.

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✅ After Repair

• 🔍 Check for leaks around the thermostat housing and upper hose with the engine running.
• 🌡️ Verify the temperature gauge stays normal during a 10–15 minute test drive.
• 🧊 After the engine fully cools, recheck coolant level and top off to the “FULL” mark.
• 🧼 Wash off any spilled coolant with water and wipe dry.

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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?

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