This procedure covers the removal and replacement of heater hoses connecting the engine to the heater core on a 2015 Kia Forte with 1.8L I4 engine.

Warnings

Tools required

Parts

• Heater inlet hose × 1 — Use OEM specification
• Heater outlet hose × 1 — Use OEM specification
• Hose clamps (if reusing old clamps shows damage) × 4 — Use OEM specification

Fluids

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

Preparation

1. Ensure engine is completely cool to the touch
2. Park vehicle on level ground and engage parking brake
3. Open hood and secure with prop rod
4. Place drain pan under engine
5. Remove engine splash shield if equipped for better access to lower coolant drain

Procedure

1. 1

   Drain cooling system
   Locate the radiator drain plug at the bottom of the radiator on the driver's side. Position drain pan underneath and slowly open the drain plug to drain coolant. If your vehicle has a coolant drain plug on the engine block, open that as well to ensure thorough drainage. Collect drained coolant in a clean container if it will be reused.
   Torque spec

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

   Locate heater hoses
   Identify the two heater hoses on the firewall behind the engine. The inlet hose (larger diameter, approximately 5/8 inch) connects from the engine to the heater core. The outlet hose (smaller diameter, approximately 1/2 inch) returns coolant from the heater core back to the engine. Trace both hoses from the firewall to their connection points on the engine.
3. 3

   Remove air intake components for access
   Disconnect the air intake duct from the throttle body by loosening the hose clamp. Remove the air filter box lid and filter element. This provides better access to the heater hoses at the engine side. Set removed components aside in a clean area.
4. 4

   Release heater inlet hose clamps
   Using hose clamp pliers or a flathead screwdriver, loosen the hose clamp at the engine connection point of the heater inlet hose. Then loosen the clamp at the firewall connection. Slide clamps away from the connection points along the hose. Note the orientation and position of spring-type clamps for reinstallation.
5. 5

   Remove heater inlet hose
   Twist the hose gently while pulling to break it free from both connection points. The hose may be stuck due to age and heat cycling. If stuck, carefully use a pick tool to break the seal between the hose and fitting, being careful not to damage the metal fittings. Remove the hose completely and inspect fittings for damage or corrosion.
   ⚠Residual coolant will drain from hoses and connections. Keep drain pan positioned to catch spillage.
6. 6

   Release heater outlet hose clamps
   Repeat the clamp removal process for the heater outlet hose. Loosen clamps at both the engine and firewall connections, then slide them away from the connection points along the hose.
7. 7

   Remove heater outlet hose
   Twist and pull the outlet hose to remove it from both connection points. This hose typically connects to the water pump or thermostat housing area. Fully remove the hose and allow any remaining coolant to drain into the pan.
8. 8

   Clean connection points
   Using a shop towel, clean all four connection points (two on firewall heater core pipes, two on engine fittings). Remove any old rubber residue, corrosion, or debris. Inspect the metal pipes for cracks, deep corrosion, or damage. The firewall heater core pipes should be smooth and free of sharp edges that could cut new hoses.
9. 9

   Install new heater inlet hose
   Slide new hose clamps onto the new heater inlet hose before installation. Position clamps approximately 1 inch from each end. Apply a thin film of coolant to the inside of both hose ends to aid installation. Push the hose firmly onto both the engine fitting and firewall pipe, ensuring each end is fully seated past the bead on the fitting. Position clamps over the connection points.
   Torque spec

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

    Install new heater outlet hose
    Repeat the installation process for the heater outlet hose. Slide clamps onto hose, lubricate hose ends with coolant, push firmly onto both fittings ensuring full seating, and position clamps over connection points. Verify that hoses are not kinked, twisted, or contacting sharp edges.
    Torque spec

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

    Reinstall air intake components
    Reinstall the air filter element and air filter box lid. Reconnect the air intake duct to the throttle body and secure with the hose clamp. Ensure all connections are secure and no tools or parts are left in the engine bay.
12. 12

    Close drain and refill cooling system
    Close and torque the radiator drain plug and engine block drain plug if opened. Fill the cooling system with Hyundai/Kia Long Life Coolant (Green) mixed to proper concentration (typically 50/50 with distilled water). Fill through the radiator cap opening slowly to allow air to escape. Fill to the proper level, then fill the coolant reservoir to the MAX line.
    ℹ️Total system capacity is 7.5 quarts. You will need approximately 2 quarts to replace what was drained during hose replacement.
    Torque spec

    Coolant Drain Plug15 Nm (11 lb-ft)
13. 13

    Bleed cooling system
    Start the engine and allow it to reach operating temperature with the radiator cap off. Run the heater on maximum heat setting. Watch the coolant level and add coolant as air pockets are purged and the level drops. Gently squeeze upper radiator hose to help release trapped air. Once the thermostat opens and coolant circulates, top off to proper level.
14. 14

    Inspect for leaks
    With engine at operating temperature, carefully inspect all four hose connections for any signs of coolant seepage. Check that hose clamps are properly positioned and tight. Inspect the area under the vehicle for any drips. Allow engine to idle for 5 minutes while monitoring coolant temperature and level.
    ⚠Engine and coolant are hot. Use caution when inspecting connections near operating temperature engine.

Reassembly

1. Install engine splash shield if it was removed
2. Verify coolant reservoir is filled to MAX line
3. Close and secure hood

Verification

• Start engine and verify heater produces hot air at idle and at 2000 RPM
• Check that engine reaches normal operating temperature without overheating
• Verify no coolant leaks at any hose connections after test drive
• Confirm coolant level remains stable in reservoir after engine cools
• Check that there are no coolant odors in cabin or visible steam from engine bay

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