🔧 Tucson - Thermostat Replacement

Replacing the thermostat on your Tucson involves draining some engine coolant, removing the thermostat housing, installing a new thermostat and seal, then refilling and bleeding the cooling system. The thermostat controls coolant flow so the engine warms up properly and does not overheat.

Difficulty Level: Beginner-Intermediate | Estimated Time: 1.5-2.5 hours

---

⚠️ Safety & Precautions

• ⚠️ Let the engine cool completely before opening the cooling system. Hot coolant can cause serious burns.
• ⚠️ Wear safety glasses and gloves. Coolant is toxic and slippery.
• ⚠️ Keep coolant away from pets and children. Dispose of old coolant properly.
• ⚠️ Do not drive your Tucson until the cooling system is refilled and air is bled out.
• ⚠️ Battery disconnect is not required for this repair.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 12mm socket
• 3/8-inch drive ratchet
• 3/8-inch drive 6-inch extension
• Flat-blade screwdriver
• Hose clamp pliers
• Torque wrench inch-pound range
• Drain pan 2-gallon minimum
• Plastic trim clip remover
• Funnel with narrow spout
• Shop towels
• Safety glasses
• Nitrile gloves

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Engine coolant thermostat - Qty: 1
• Thermostat gasket or seal - Qty: 1
• Asian vehicle long-life coolant, phosphate-enhanced ethylene glycol type - Qty: 1 gallon concentrate or 2 gallons premixed 50/50
• Distilled water - Qty: 1 gallon if using concentrate

---

📋 Before You Begin

• Park your Tucson on level ground and set the parking brake.
• Let the engine sit until it is fully cold, ideally overnight.
• Open the hood and remove the radiator cap only when the engine is cold.
• Place a drain pan under the front of the radiator before opening any coolant drain.
• A torque wrench tightens bolts to a measured amount so small aluminum parts are not cracked.
• Hose clamp pliers are pliers made to squeeze spring-style hose clamps safely.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the Lower Engine Splash Shield

• Use the plastic trim clip remover to remove the plastic retainers from the lower splash shield.
• Use the 10mm socket and ratchet to remove any 10mm bolts holding the shield.
• Lower the splash shield and set it aside.
• Tip: Keep clips grouped together.

Step 2: Drain Some Coolant

• Place the 2-gallon drain pan under the radiator drain area.
• Use your hand or a flat-blade screwdriver to carefully open the radiator drain cock at the bottom of the radiator.
• Drain about 1 gallon of coolant, or enough so the upper engine outlet area will not spill heavily.
• Close the radiator drain cock by hand until snug. Do not overtighten it.

Step 3: Locate the Thermostat Housing

• Follow the large lower radiator hose from the radiator toward the engine.
• The hose connects to the thermostat housing on the engine side.
• Use shop towels around the housing area to catch leftover coolant.

Step 4: Remove the Radiator Hose from the Thermostat Housing

• Use hose clamp pliers to squeeze the spring clamp on the radiator hose.
• Slide the clamp back onto the hose, away from the thermostat housing neck.
• Use a flat-blade screwdriver gently at the hose edge only if the hose is stuck.
• Twist the hose by hand, then pull it off the housing.
• Tip: Do not pry against aluminum.

Step 5: Remove the Thermostat Housing

• Use the 12mm socket, 6-inch extension, and ratchet to remove the thermostat housing bolts.
• Pull the housing straight away from the engine.
• Note the thermostat direction before removing it. The spring side faces into the engine.

Step 6: Remove the Old Thermostat and Seal

• Remove the old thermostat by hand.
• Remove the old thermostat gasket or rubber seal by hand.
• Use shop towels to clean coolant from the sealing surface.
• Do not use metal scrapers on the aluminum surface.

Step 7: Install the New Thermostat

• Install the new thermostat with the spring side facing into the engine.
• If the thermostat has a small jiggle valve or bleed pin, position it at the top.
• Install the new gasket or seal onto the thermostat or housing as supplied.
• Tip: Match the old thermostat orientation.

Step 8: Reinstall the Thermostat Housing

• Position the thermostat housing squarely against the engine.
• Thread the bolts in by hand first to avoid cross-threading.
• Use the 12mm socket and torque wrench to tighten the housing bolts evenly.
• Torque to 15-20 Nm (11-15 ft-lbs)

Step 9: Reconnect the Radiator Hose

• Push the radiator hose fully onto the thermostat housing neck by hand.
• Use hose clamp pliers to move the spring clamp back to its original position.
• Make sure the clamp sits behind the raised bead on the housing neck.

Step 10: Refill the Cooling System

• Use the funnel to fill the radiator with the correct 50/50 coolant mixture.
• Fill slowly to reduce trapped air.
• Fill the coolant reservoir to the FULL mark.
• Leave the radiator cap off for the first warm-up step.

Step 11: Bleed Air from the Cooling System

• Start the engine and let it idle with the radiator cap off.
• Set the heater controls inside your Tucson to full hot and low fan speed.
• Watch the coolant level in the radiator. Add coolant with the funnel as the level drops.
• When the upper radiator hose becomes hot, the thermostat has opened.
• Install the radiator cap once air bubbles reduce and the coolant level stays steady.

Step 12: Reinstall the Lower Splash Shield

• Use the plastic trim clip remover to align the plastic retainers.
• Use the 10mm socket and ratchet to reinstall the splash shield bolts.
• Tighten the bolts snugly. Do not overtighten plastic shield fasteners.

---

✅ After Repair

• Let your Tucson reach normal operating temperature while watching the temperature gauge.
• Check around the thermostat housing and radiator hose for leaks.
• Test drive for 10-15 minutes, then park and let the engine cool fully.
• After it cools, recheck the radiator and reservoir levels. Top off as needed.
• If the heater blows cold air or the temperature gauge rises, shut the engine off and recheck for trapped air.
• Dispose of old coolant at a recycling center or auto parts store that accepts used coolant.

---

💰 DIY vs Shop Cost

Shop Cost: $180-$330 (parts + labor)

DIY Cost: $35-$90 (parts only)

You Save: $145-$240 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-1.5 hours.

---

🎯 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.