Replace the coolant bypass pipe on a 2015 Kia Forte 1.8L I4 engine to resolve coolant leaks or flow restrictions in the cooling system bypass circuit.

Warnings

Tools required

Parts

• Coolant bypass pipe × 1 — Use OEM Kia part for proper fit
• Coolant bypass pipe O-rings/gaskets × 1 — Usually included with pipe assembly
• Hose clamps (if reusing original not recommended) × 2 — Replace with OEM spring clamps

Fluids

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

Preparation

1. Ensure engine is completely cold to the touch (wait at least 2 hours after last operation)
2. Park vehicle on level surface and engage parking brake
3. Remove engine cover by pulling upward on retaining clips
4. Place drain pan under radiator drain plug location
5. Open radiator cap slowly to release any residual pressure

Procedure

1. 1

   Drain cooling system
   Locate the radiator drain plug at the bottom driver's side of the radiator. Open the drain plug and drain approximately 2-3 quarts of coolant into the drain pan. You do not need to drain the entire system, just enough to drop the level below the bypass pipe. Close drain plug when coolant level is below the thermostat housing.
   Torque spec

   Coolant Drain Plug15 Nm (11 lb-ft)
2. 2

   Access bypass pipe area
   From the top of the engine bay, locate the bypass pipe on the firewall side of the engine block, near the thermostat housing. Remove the air intake duct if needed for better access. You may need to work from underneath the vehicle for better visibility and tool access to the lower connection point.
3. 3

   Disconnect upper coolant hose
   Locate the coolant hose connected to the upper portion of the bypass pipe near the thermostat housing. Using hose clamp pliers or a flathead screwdriver, loosen and reposition the hose clamp. Twist the hose gently to break the seal, then pull it off the bypass pipe fitting. Be prepared for residual coolant to drain out.
   ⚠Coolant hoses may be brittle. Avoid excessive twisting force that could tear the hose. Replace hose if cracking or damage is observed.
4. 4

   Disconnect lower coolant connection
   Follow the bypass pipe down to its lower connection point at the engine block or water pump area. Loosen the hose clamp and disconnect the lower hose or note the direct mounting configuration. If the pipe connects directly to the block with O-rings, proceed to remove mounting hardware.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
5. 5

   Remove bypass pipe mounting hardware
   Locate the mounting bolts securing the bypass pipe to the engine block or thermostat housing (typically 1-2 bolts, 10mm or 12mm). Remove these bolts completely and set aside. Note the orientation and routing of the bypass pipe for installation of the new component.
   Torque spec

   Housing Bolts13 Nm (10 lb-ft)
6. 6

   Remove old bypass pipe
   Carefully extract the bypass pipe from the engine bay. You may need to wiggle it gently to free the O-ring seals from their grooves. Inspect the pipe for cracks, corrosion, or damage to confirm replacement is necessary. Remove and discard all old O-rings and gaskets.
7. 7

   Clean mating surfaces
   Using a plastic gasket scraper and wire brush, thoroughly clean all mating surfaces on the engine block, thermostat housing, and any connection points. Remove all old gasket material, corrosion, and debris. Wipe clean with a shop towel. Inspect surfaces for damage or deep corrosion that could prevent proper sealing.
   ℹ️Do not use metal scrapers on aluminum surfaces as this can cause scratches that lead to leaks. Use only plastic tools.
8. 8

   Prepare new bypass pipe
   Unpack the new bypass pipe and verify all O-rings and seals are included and properly positioned in their grooves. Lightly coat all O-rings with fresh coolant to aid installation and ensure proper sealing. Verify the new pipe matches the old pipe in configuration and fitting locations.
9. 9

   Install new bypass pipe
   Carefully position the new bypass pipe into place, aligning it with the mounting holes and connection points. Press the pipe firmly into position to seat the O-rings in their grooves. Ensure the pipe is fully seated before installing mounting hardware. Thread mounting bolts by hand first to prevent cross-threading.
   ⚠Do not force the pipe into position. If resistance is felt, verify O-rings are properly lubricated and aligned. Forcing can damage seals or crack the pipe.
   Torque spec

   Housing Bolts13 Nm (10 lb-ft)
10. 10

    Reconnect coolant hoses
    Reconnect the upper and lower coolant hoses to the bypass pipe fittings. Ensure hoses are pushed fully onto the fittings until they seat against the stop ridge. Position hose clamps over the connection area and tighten to specification. Verify clamps are positioned properly over both the hose and the raised bead on the fitting.
    Torque spec

    Hose Clamps3 Nm (2 lb-ft)
11. 11

    Refill cooling system
    Using a funnel, slowly add Hyundai/Kia Long Life Coolant (Green) to the radiator fill neck. Fill until coolant reaches the neck. Locate the cooling system bleed screw on the thermostat housing or upper radiator hose area. Open the bleed screw and continue adding coolant until air-free coolant flows from the bleeder. Close the bleed screw to specification.
    ℹ️Bleeding is critical to prevent air pockets that can cause overheating. Take time to ensure all air is purged from the system.
    Torque spec

    Bleed Screw6 Nm (5 lb-ft)
12. 12

    Burp cooling system
    Install the radiator cap. Start the engine and allow it to idle with the heater on maximum setting. Monitor the temperature gauge and watch for proper thermostat opening (temperature should rise then stabilize). Run engine until cooling fans cycle on. Shut off engine, allow to cool briefly, then recheck coolant level and top off as needed. Repeat bleed screw procedure if necessary.

Reassembly

1. Reinstall air intake duct and engine cover
2. Double-check all hose clamps are tight and properly positioned
3. Verify no tools or parts were left in the engine bay
4. Clean up any coolant spills from engine bay and underside of vehicle

Verification

• With engine cold, verify coolant level is at the FULL COLD mark on the reservoir
• Inspect all bypass pipe connections for signs of coolant leakage
• Start engine and bring to operating temperature while monitoring for leaks around the new bypass pipe
• Verify engine reaches normal operating temperature and cooling fans cycle properly
• After first test drive, recheck coolant level when engine is cold and top off if needed
• Monitor coolant level over the next few days to ensure no slow leaks are present

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