Radiator Hoses - Both

Replace both upper and lower radiator hoses on the 2016-2021 Honda Civic 1.5L Turbo engine, including coolant drain and refill with Honda Type 2 coolant.

Warnings

Tools required

Parts

• Upper radiator hose × 1 — 19504-5AA-A00 or equivalent OEM
• Lower radiator hose × 1 — 19505-5AA-A00 or equivalent OEM
• Hose clamps (set of 4) × 4 — Use OEM specification spring clamps or screw type

Fluids

• Honda Type 2 Coolant (Blue) — 6.5 qt

Preparation

1. Ensure engine is completely cold (at least 2 hours after last operation)
2. Park vehicle on level ground and engage parking brake
3. Place drain pan under the radiator drain plug located on the driver's side lower corner of the radiator
4. Remove the engine cover by pulling upward on the front edge, then lifting off
5. Remove the splash shield fasteners if necessary for better access to lower radiator hose

Procedure

1. 1

   Drain cooling system
   Slowly turn the radiator cap counterclockwise to relieve any residual pressure, then remove completely. Locate the coolant drain plug on the lower driver's side of the radiator. Using a 10mm socket, carefully loosen and remove the drain plug, allowing coolant to drain completely into the drain pan. This will take several minutes.
   Torque spec

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

   Remove upper radiator hose from radiator
   Locate the upper radiator hose connection at the top driver's side of the radiator. If equipped with a spring clamp, use hose clamp pliers to compress and slide the clamp away from the connection point. If equipped with a screw-type clamp, use a flathead screwdriver to loosen. Twist the hose gently while pulling to break the seal and remove it from the radiator neck.
3. 3

   Remove upper radiator hose from thermostat housing
   Follow the upper radiator hose to the engine-side connection at the thermostat housing on the passenger side of the engine. Release the hose clamp using the same method as in the previous step. Twist and pull the hose to disconnect it from the thermostat housing. Remove the upper hose completely from the vehicle.
4. 4

   Remove lower radiator hose from radiator
   Locate the lower radiator hose connection at the bottom of the radiator on the passenger side. You may need to reach from underneath the vehicle for better access. Release the hose clamp and twist the hose to break the seal. Pull the hose off the radiator outlet. Be prepared for additional coolant drainage.
5. 5

   Remove lower radiator hose from water pump
   Follow the lower radiator hose to its connection point at the water pump inlet on the lower front of the engine block. Release the hose clamp and twist the hose to break the seal from the water pump. Remove the lower hose completely from the vehicle. Inspect both the radiator and engine connection points for corrosion or damage.
6. 6

   Clean and inspect connection points
   Using a clean shop towel, wipe down all four connection points (radiator upper and lower, thermostat housing, and water pump inlet). Remove any old coolant residue, corrosion, or debris. Inspect the connection necks for cracks or damage. Check that all connection surfaces are smooth to ensure proper seal with new hoses.
7. 7

   Install new upper radiator hose
   Position new hose clamps on the new upper radiator hose before installation. Connect the upper hose to the thermostat housing first, pushing firmly until it seats completely against the stop. Slide the clamp into position approximately 10-15mm from the end of the hose and tighten. Connect the radiator end of the upper hose, ensuring it is fully seated, then position and tighten the clamp.
   Torque spec

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

   Install new lower radiator hose
   Position new hose clamps on the new lower radiator hose. Connect the water pump end first, pushing the hose firmly onto the inlet until fully seated. Position the clamp and tighten to specification. Route the hose to the radiator outlet, ensuring no kinks or sharp bends. Push the hose onto the radiator outlet until fully seated, then position and tighten the clamp.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
9. 9

   Reinstall drain plug and refill coolant
   Clean the drain plug threads and reinstall into the radiator, torquing to specification. Using a funnel, slowly pour Honda Type 2 coolant into the radiator opening until it reaches the bottom of the filler neck. Pause periodically to allow air bubbles to escape. Once filled, pour coolant into the coolant reservoir until it reaches the MAX line.
   Torque spec

   Coolant Drain Plug15 Nm (11 lb-ft)
10. 10

    Bleed cooling system
    With the radiator cap still off, start the engine and allow it to warm up to normal operating temperature while monitoring coolant level. The thermostat will open and coolant level will drop as air purges from the system. Add additional coolant as needed to maintain proper level. Run the engine until the cooling fans cycle on, then turn off the engine and allow to cool for 15 minutes.
    ⚠Keep hands clear of the cooling fan, which may activate automatically at any time during this process.
11. 11

    Final coolant level check
    Once engine has cooled, check coolant level in the radiator and add coolant if necessary to bring it to the bottom of the filler neck. Install the radiator cap by aligning the tabs and turning clockwise until it locks. Check the coolant reservoir level and adjust to the MAX line if needed. Reinstall the engine cover and any removed splash shields.

Reassembly

1. Ensure all hose clamps are properly positioned and tightened to specification
2. Verify both radiator hoses are routed without kinks or contact with sharp edges
3. Confirm radiator cap is properly locked in place
4. Reinstall engine cover and any removed splash shields
5. Dispose of used coolant at an approved recycling facility

Verification

• Start the engine and check all four hose connections for coolant leaks while engine warms up
• Verify cooling fans cycle on when engine reaches operating temperature
• Check coolant level in reservoir after engine cools - should be at MAX line
• Test drive vehicle for 10-15 minutes and recheck for leaks and proper coolant level
• Monitor coolant level over the next few days and top off if necessary as any remaining air purges from the system

More procedures for this vehicle