This procedure covers the removal and replacement of the coolant reservoir (expansion tank) on a 2016-2024 Hyundai Tucson with the 2.5L I4 AWD engine.

Warnings

Tools required

Parts

• Coolant reservoir/expansion tank × 1 — Use OEM specification
• Reservoir cap × 1 — Reuse if in good condition or replace with OEM
• Hose clamps × 2 — Replace if corroded or damaged

Fluids

• Hyundai/Kia Long Life Coolant (Green) — 2 qt

Preparation

1. Ensure engine is completely cool (at least 2 hours after last operation)
2. Park vehicle on level ground and engage parking brake
3. Open hood and prop securely
4. Place drain pan beneath engine compartment

Procedure

1. 1

   Release cooling system pressure
   Slowly turn the reservoir cap counterclockwise to the first detent and allow any residual pressure to escape. Wait for hissing to stop, then continue turning to remove the cap completely. Set the cap aside on a clean surface.
2. 2

   Drain coolant from reservoir
   Using a turkey baster, hand pump, or similar device, remove as much coolant as possible from the reservoir and transfer to the drain pan. This minimizes spillage during hose removal. Alternatively, you may drain the entire cooling system via the radiator drain petcock if performing additional cooling system service.
3. 3

   Disconnect lower coolant hose
   Locate the lower coolant hose connected to the bottom of the reservoir. Use hose clamp pliers or a flathead screwdriver to loosen the hose clamp and slide it down the hose away from the reservoir. Twist and pull the hose off the reservoir nipple. Allow any remaining coolant to drain into the pan.
   Torque spec

   Hose Clamps4 Nm (3 lb-ft)
4. 4

   Disconnect upper coolant hose
   Locate the upper coolant hose (overflow line) connected to the side or top of the reservoir. Loosen the hose clamp and slide it away from the reservoir connection point. Remove the hose from the reservoir nipple. Have a shop towel ready to catch any coolant drips.
   Torque spec

   Hose Clamps4 Nm (3 lb-ft)
5. 5

   Remove reservoir mounting bolts
   Locate the two mounting bolts securing the reservoir to the inner fender or radiator support bracket. Using a 10mm socket, remove both mounting bolts completely. Support the reservoir while removing the second bolt to prevent it from falling.
   Torque spec

   Reservoir Mounting Bolts8 Nm (6 lb-ft)
6. 6

   Remove reservoir from vehicle
   Carefully lift the coolant reservoir straight up and out of the engine bay. Tilt as needed to clear any obstructions. Pour any remaining coolant from the old reservoir into the drain pan. Inspect the old reservoir for cracks, damage, or contamination.
7. 7

   Prepare new reservoir
   Inspect the new reservoir for damage and verify it matches the old unit. Check that all hose connection nipples are clean and free of debris. If reusing hose clamps, inspect them for corrosion or damage and replace if necessary.
8. 8

   Install new reservoir
   Position the new reservoir into the mounting location, aligning the mounting holes with the bracket. Install both mounting bolts hand-tight, ensuring the reservoir is properly seated. Torque both mounting bolts to specification using a torque wrench.
   Torque spec

   Reservoir Mounting Bolts8 Nm (6 lb-ft)
9. 9

   Connect coolant hoses
   Connect the lower coolant hose to the reservoir bottom nipple, pushing it on until fully seated. Slide the hose clamp into position over the connection point and tighten to specification. Repeat for the upper overflow hose. Ensure both hoses are routed without kinks or sharp bends.
   Torque spec

   Hose Clamps4 Nm (3 lb-ft)
10. 10

    Refill cooling system
    Using a funnel, slowly fill the reservoir with fresh Hyundai/Kia Long Life Coolant (Green) to the FULL/MAX mark. If system was fully drained, also refill through the radiator cap opening if accessible. Add coolant slowly to minimize air entrapment.
11. 11

    Bleed cooling system
    Locate the cooling system bleed screw on the thermostat housing or upper radiator hose connection. Open the bleed screw slightly (do not remove completely). Start the engine and allow it to idle with the reservoir cap off. Add coolant as the level drops and watch for coolant to flow from the bleed screw without air bubbles. Close the bleed screw when coolant flows steadily.
    ⚠Keep hands and tools clear of the serpentine belt and cooling fans during this step. Fans may activate suddenly.
    Torque spec

    Bleed Screw7 Nm (5 lb-ft)
12. 12

    Complete system bleeding
    Allow the engine to reach normal operating temperature (thermostat open) while monitoring the coolant level. Add coolant to the reservoir as needed to maintain proper level. Run the engine for 5-10 minutes after reaching operating temperature, then shut off and allow to cool slightly before installing the reservoir cap.

Reassembly

1. Verify all hose clamps are tightened to specification and hoses are properly seated
2. Confirm reservoir mounting bolts are torqued correctly and reservoir is secure
3. Install reservoir cap and turn clockwise until it clicks into place
4. Wipe down any coolant spills in the engine bay with shop towels

Verification

• Check coolant level in reservoir with engine cold - should be at FULL/MAX mark
• Inspect all hose connections for leaks with engine at operating temperature
• Verify no coolant drips or puddles beneath vehicle after test drive
• Confirm engine temperature gauge reads normal during operation with no overheating
• Recheck coolant level after 24 hours of normal driving and top off if necessary

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