Radiator Hose - Lower

This procedure covers removal and replacement of the lower radiator hose on a 2016-2021 Honda Civic with the 1.5L turbocharged engine.

Warnings

Tools required

Parts

• Lower radiator hose × 1 — 19502-5AA-A01 or equivalent
• Hose clamps (if reusing originals shows wear) × 2 — Use OEM specification

Fluids

• Honda Type 2 Coolant (Blue) — 2 qt

Preparation

1. Ensure engine is completely cold to the touch
2. Raise and secure the front of the vehicle on jack stands or drive onto ramps for underside access
3. Remove the engine splash shield (multiple plastic clips and bolts) for access to the lower radiator hose
4. Place drain pan underneath the radiator drain plug location
5. Remove the radiator cap slowly to release any residual pressure

Procedure

1. 1

   Drain the cooling system
   Locate the radiator drain plug on the driver's side lower corner of the radiator. Open the drain plug and allow coolant to drain into the pan. Once drained, close the drain plug hand-tight.
2. 2

   Access the lower radiator hose connections
   From underneath the vehicle, locate the lower radiator hose which runs from the bottom of the radiator on the passenger side to the water pump on the engine block. Identify both hose clamps at the radiator outlet and water pump inlet.
3. 3

   Remove the radiator-side hose clamp
   Using hose clamp pliers or a flathead screwdriver, loosen the clamp securing the lower hose to the radiator outlet. Slide the clamp away from the connection point along the hose. Note the orientation and position of the clamp for reinstallation.
4. 4

   Remove the water pump-side hose clamp
   Loosen the clamp securing the lower hose to the water pump inlet on the engine block. Slide this clamp away from the connection point. Expect residual coolant to drain when the hose is disconnected.
5. 5

   Disconnect the lower radiator hose
   Twist the hose at both connection points to break the seal, then pull firmly to remove from the radiator outlet and water pump inlet. The hose may require significant force if it has been in place for an extended period. Allow remaining coolant to drain into the pan.
6. 6

   Clean the connection surfaces
   Thoroughly clean the radiator outlet and water pump inlet using shop rags. Remove any old coolant residue, corrosion, or debris. Inspect both metal surfaces for damage or excessive corrosion that could prevent a proper seal.
7. 7

   Install the new lower radiator hose
   Position new hose clamps on the new hose before installation. Slide the radiator end of the new hose onto the radiator outlet, ensuring it seats fully against the ridge. Then connect the engine end to the water pump inlet, verifying full seating at both ends.
8. 8

   Secure the hose clamps
   Position both hose clamps approximately 10mm from the end of each hose connection. Tighten each clamp to specification, ensuring the hose remains properly seated during tightening.
   Torque spec

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

   Refill the cooling system
   Using a funnel, pour Honda Type 2 coolant into the radiator until full. Start the engine and allow it to reach operating temperature with the radiator cap off. Add coolant as the level drops during thermostat opening and air purging. Monitor for leaks at both hose connections.
10. 10

    Bleed the cooling system
    With the engine at operating temperature, run the heater at maximum temperature to circulate coolant through the entire system. Squeeze the upper radiator hose several times to help release air pockets. Top off coolant as needed until the level stabilizes.

Reassembly

1. Reinstall the engine splash shield using all original fasteners
2. Install the radiator cap securely once the engine has cooled and coolant level is verified
3. Lower the vehicle from jack stands or ramps
4. Check coolant reservoir level and fill to the MAX line with a 50/50 mixture of Honda Type 2 coolant

Verification

• Start the engine and visually inspect both hose connections for coolant leaks while the engine warms up
• Verify the temperature gauge reaches normal operating range without overheating
• After the first drive cycle, recheck coolant level when engine is cold and top off if necessary
• Inspect the hose connections again after 100 miles of driving to ensure clamps remain tight and no seepage has occurred

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