Coolant Bypass Pipe

This procedure covers the removal and replacement of the coolant bypass pipe on the 2016-2024 Hyundai Tucson 2.5L I4 AWD engine, including proper coolant draining, refilling, and system bleeding.

Warnings

Tools required

Parts

• Coolant bypass pipe × 1 — Use OEM Hyundai part
• Bypass pipe O-rings × 2 — Usually included with pipe
• Hose clamps (if corroded) × 2 — Use OEM specification

Fluids

• Hyundai/Kia Long Life Coolant (Green) — 10 qt

Preparation

1. Ensure engine is completely cold (wait minimum 2 hours after last operation)
2. Park vehicle on level surface and engage parking brake
3. Disconnect negative battery terminal to prevent accidental fan activation
4. Remove engine cover by pulling upward on four retention clips
5. Place drain pan under radiator drain petcock located at bottom of radiator driver's side

Procedure

1. 1

   Drain cooling system
   Slowly remove radiator cap to release any residual pressure. Open radiator drain petcock at bottom of radiator by turning counterclockwise and allow coolant to drain into pan. Once draining slows, open bleed screw located on top of thermostat housing to allow complete drainage. Allow 10-15 minutes for complete drainage.
2. 2

   Remove upper radiator hose connection
   Use hose clamp pliers to compress and slide the hose clamp away from the thermostat housing connection. Twist and pull the upper radiator hose off the thermostat housing nipple. Be prepared for residual coolant spillage.
3. 3

   Access bypass pipe area
   Remove air intake duct between air filter box and throttle body for better access. Disconnect the electrical connector from the coolant temperature sensor if it interferes with access. Position shop towels below the bypass pipe area to catch residual coolant.
4. 4

   Disconnect bypass pipe hose connections
   Locate the coolant bypass pipe on the driver's side of the engine block. Using hose clamp pliers, compress and reposition the hose clamps at both ends of the bypass pipe (thermostat housing end and water pump end). Twist hoses gently to break seal, then pull off the bypass pipe nipples. Note orientation and routing of hoses for reassembly.
5. 5

   Remove bypass pipe mounting bolts
   Using a 10mm socket with extension, remove the two mounting bolts securing the bypass pipe bracket to the engine block. Support the pipe while removing the second bolt to prevent it from dropping. Carefully withdraw the bypass pipe from its mounting position, maneuvering around nearby components.
   Torque spec

   Housing Bolts14 Nm (10 lb-ft)
6. 6

   Inspect and clean mating surfaces
   Inspect the bypass pipe nipples and mating hose surfaces for cracks, corrosion, or damage. Use wire brush to clean any corrosion from the mounting bracket area on the engine block. Wipe all mating surfaces clean with shop towels. Inspect hose clamps and replace if corroded or damaged.
7. 7

   Prepare new bypass pipe
   Remove new bypass pipe from packaging and verify all O-rings are properly seated in their grooves. Lightly coat O-rings and hose nipples with fresh coolant to ease installation and prevent O-ring damage. Compare new pipe to old pipe to confirm correct replacement part.
8. 8

   Install new bypass pipe
   Position new bypass pipe in mounting location, carefully routing around nearby components in reverse of removal. Align mounting bracket holes with engine block threaded holes. Hand-start both mounting bolts to ensure proper thread engagement. Tighten mounting bolts to specification using torque wrench in a criss-cross pattern.
   Torque spec

   Housing Bolts14 Nm (10 lb-ft)
9. 9

   Reconnect coolant hoses
   Push hoses firmly onto bypass pipe nipples until they bottom out against the O-ring seat (you should feel resistance and then a slight give when properly seated). Ensure hoses are routed in original positions without kinks or sharp bends. Slide hose clamps into position 1/4 inch from end of each hose and tighten to specification using torque wrench.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
10. 10

    Reconnect components and close drain
    Reconnect upper radiator hose to thermostat housing and secure with hose clamp. Reconnect coolant temperature sensor electrical connector if previously disconnected. Reinstall air intake duct. Close radiator drain petcock and tighten to specification. Ensure bleed screw remains open for filling process.
    Torque spec

    Drain Petcock7 Nm (5 lb-ft)
11. 11

    Refill cooling system
    Using coolant funnel in radiator neck, slowly pour Hyundai/Kia Long Life Coolant (Green) into system. Fill slowly to allow air to escape through open bleed screw. When coolant flows steadily from bleed screw without air bubbles, close bleed screw to specification. Continue filling radiator to neck. Fill coolant reservoir to MAX line. Install radiator cap.
    Torque spec

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

    Bleed cooling system and check for leaks
    Reconnect negative battery terminal. Start engine and allow to warm up to operating temperature with heater on maximum heat setting. Monitor temperature gauge to ensure normal operation. Watch for coolant leaks around bypass pipe connections and hose clamps. Once cooling fan cycles on and off twice, shut off engine and allow to cool for 30 minutes.
    ⚠Do not remove radiator cap while engine is warm. Monitor temperature gauge and shut down immediately if overheating occurs.
13. 13

    Recheck coolant level and complete bleeding
    After engine has cooled, carefully remove radiator cap and check coolant level. Top off radiator to neck if needed. Check coolant reservoir level and top off to MAX line if needed. Briefly open bleed screw to release any remaining trapped air, then retighten to specification. Reinstall radiator cap. Wipe down all surfaces and inspect for any signs of leakage.
    Torque spec

    Bleed Screw7 Nm (5 lb-ft)

Reassembly

1. Reinstall engine cover by aligning clips and pressing down firmly until all four clips snap into place
2. Remove all tools and shop towels from engine compartment
3. Dispose of old coolant properly at authorized recycling facility
4. Record repair in vehicle maintenance log with date and mileage

Verification

• Inspect all bypass pipe connections and hose clamps for any signs of coolant seepage or wetness
• Verify coolant level is at MAX line in reservoir when engine is cold
• Start engine and confirm normal operating temperature is reached without overheating
• Verify heater produces hot air at idle and under acceleration
• Check that cooling fan activates at proper temperature
• Perform cold engine inspection after 24 hours to confirm no leaks have developed and coolant level remains stable

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