Heater Hoses

This procedure covers the removal and replacement of heater hoses on the 2018-2024 Honda Accord 1.5L Turbo engine, including draining coolant and refilling the cooling system.

Warnings

Tools required

Parts

• Heater hose inlet (upper) × 1 — Use OEM specification
• Heater hose outlet (lower) × 1 — Use OEM specification
• Hose clamps × 4 — Spring type or worm gear, 19-29mm
• Engine coolant × 1 — Honda Type 2 Blue coolant

Fluids

• Honda Type 2 Coolant (Blue) — 6 qt

Preparation

1. Ensure engine is completely cold before starting work
2. Park vehicle on level ground and engage parking brake
3. Remove engine cover by pulling upward on front edge, then lifting away
4. Place drain pan under radiator drain plug location on passenger side of radiator

Procedure

1. 1

   Drain cooling system
   Slowly loosen the radiator cap to release any residual pressure. Remove the radiator cap completely. Locate the coolant drain plug on the lower passenger side of the radiator. Remove the drain plug using a 10mm socket and allow coolant to drain completely into the drain pan. Reinstall and torque the drain plug.
   Torque spec

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

   Access heater hoses
   From the engine bay, locate the two heater hoses on the firewall behind the engine block. The upper hose connects to the inlet pipe and the lower hose connects to the outlet pipe. Remove any wire harness clips or brackets that may obstruct access to the hoses. You may need to reach from above or below the intake manifold depending on which hose you're accessing.
3. 3

   Remove upper heater hose
   Using hose clamp pliers or a flathead screwdriver, release the spring clamp or loosen the worm gear clamp at the engine-side connection of the upper heater hose. Slide the clamp away from the connection point. Repeat for the firewall-side connection. Twist the hose gently while pulling to break the seal, then remove the hose. Allow any remaining coolant to drain into the drain pan.
4. 4

   Remove lower heater hose
   Release the hose clamps at both ends of the lower heater hose using the same method as the upper hose. Twist and pull the hose to remove it from both the engine connection and the firewall heater core pipe. Be prepared for additional coolant to drain from the hose and connections.
5. 5

   Inspect heater core pipes
   Examine the metal heater core pipes on the firewall for corrosion, damage, or deterioration. Check the rubber seal surfaces for pitting or corrosion that could prevent proper sealing. Clean the connection points with a shop towel to remove old coolant residue and ensure a clean mating surface for the new hoses.
6. 6

   Install new upper heater hose
   Position new hose clamps on the new upper heater hose before installation. Apply a thin film of coolant to the inside ends of the hose to aid installation. Push the hose firmly onto the engine-side connection first, ensuring it seats completely onto the pipe. Then connect the firewall side. Position the clamps 6-10mm from the end of each hose and secure them.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
7. 7

   Install new lower heater hose
   Position new hose clamps on the new lower heater hose. Apply a thin film of coolant to the inside ends of the hose. Install the hose onto both the engine connection and the heater core pipe on the firewall, ensuring full seating. Position the clamps 6-10mm from the end of each hose and torque to specification.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
8. 8

   Reinstall components
   Reinstall any wire harness clips or brackets that were removed for access. Ensure no wires or hoses are pinched or interfering with the new heater hoses. Verify all connections are secure and clamps are properly positioned.
9. 9

   Refill cooling system
   Using a funnel, slowly fill the cooling system with Honda Type 2 (blue) coolant through the radiator cap opening. Fill until coolant reaches the base of the filler neck. Also fill the coolant reservoir to the MAX line. Start the engine and allow it to reach operating temperature with the heater on full hot and fan on low. Watch the coolant level and add as needed as air purges from the system.
   ⚠Engine will be hot during this step. Keep hands away from moving parts and hot surfaces.
10. 10

    Bleed air from system
    With the engine at operating temperature, carefully squeeze the upper radiator hose several times to help release trapped air bubbles. Monitor the coolant level in the radiator and add coolant as the level drops. Continue running the engine for 10-15 minutes total, ensuring the radiator fan cycles on and off. Top off coolant level and install the radiator cap securely.

Reassembly

1. Reinstall engine cover by aligning rear tabs and pressing down firmly on front edge until clips engage
2. Wipe down any coolant spills in the engine bay with shop towels
3. Dispose of old coolant properly at a recycling center or automotive shop

Verification

• With engine at operating temperature, inspect all heater hose connections for leaks
• Check coolant reservoir level is between MIN and MAX lines
• Verify heater blows hot air when set to maximum temperature
• Check for wetness or staining around hose clamp areas indicating seepage
• After initial test drive, recheck coolant level when engine is cold and top off if needed

Related trouble codes on this vehicle

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