Complete coolant system flush and refill for the 2016-2021 Honda Civic 1.5L Turbo, replacing old coolant with Honda Type 2 (Blue) coolant to maintain proper engine cooling and corrosion protection.

Warnings

Tools required

Parts

• Radiator drain plug washer × 1 — 19044-R70-A01 or equivalent

Fluids

• Honda Type 2 Coolant (Blue) — 6 qt

Preparation

1. Ensure engine is completely cold (wait minimum 2 hours after last operation)
2. Park vehicle on level ground and engage parking brake
3. Remove engine splash shield/undertray if equipped for easier access to drain plug
4. Locate coolant reservoir tank on passenger side of engine bay
5. Place drain pan under radiator drain plug location (driver side lower corner of radiator)

Procedure

1. 1

   Remove radiator cap and reservoir cap
   Slowly turn the radiator cap counterclockwise to release any residual pressure, then remove completely. Remove the coolant reservoir cap to allow proper draining and venting.
2. 2

   Drain radiator via drain plug
   Position drain pan under the radiator drain plug located at the driver side lower corner of the radiator. Remove the drain plug completely and allow coolant to drain fully. Inspect and replace the drain plug washer if damaged or hardened.
   Torque spec

   Block Drain Plug25 Nm (18 lb-ft)
3. 3

   Drain coolant reservoir
   Remove the coolant reservoir from its mounting bracket by releasing the clips. Pour any remaining coolant from the reservoir into the drain pan. Rinse the reservoir with clean water to remove sediment, then reinstall in mounting bracket.
4. 4

   Open bleeder screw
   Locate the bleeder screw on the coolant pipe near the thermostat housing on the passenger side of the engine. Loosen the bleeder screw 2-3 turns to allow air to escape during the refill process. Do not remove completely.
   Torque spec

   Bleed Screw7 Nm (5 lb-ft)
5. 5

   Reinstall drain plug
   Install a new drain plug washer onto the drain plug. Thread the drain plug into the radiator by hand, then torque to specification. Ensure proper seating to prevent leaks.
   Torque spec

   Block Drain Plug25 Nm (18 lb-ft)
6. 6

   Begin coolant refill
   Using a funnel, begin slowly pouring Honda Type 2 (Blue) coolant into the radiator filler neck. Pour slowly to minimize air pockets. Continue filling until coolant begins to flow from the open bleeder screw, indicating air is being purged from the system.
7. 7

   Close bleeder screw
   Once coolant flows steadily from the bleeder screw without air bubbles, tighten the bleeder screw to specification while coolant continues to flow. Wipe away any spilled coolant.
   Torque spec

   Bleed Screw7 Nm (5 lb-ft)
8. 8

   Complete radiator fill
   Continue adding coolant to the radiator until the level reaches the base of the filler neck. Install the radiator cap securely. Fill the coolant reservoir to the MAX line marked on the tank.
9. 9

   Run engine and burp system
   Start the engine and let it run at idle with the climate control set to maximum heat and fan on high. Allow engine to reach normal operating temperature (cooling fans cycle on). Monitor coolant level in reservoir and add as needed. Rev engine to 3000 RPM briefly 2-3 times to help purge remaining air.
   ⚠Monitor temperature gauge closely. If temperature rises above normal, shut off engine immediately and allow to cool before investigating.
10. 10

    Final level check
    After engine reaches operating temperature and fans have cycled, shut off engine and allow to cool for 30 minutes. Recheck coolant level in reservoir when engine is warm (not hot). Level should be between MIN and MAX marks. Top off if necessary. Check for leaks around drain plug and bleeder screw.

Reassembly

1. Reinstall engine splash shield/undertray if removed
2. Wipe down any coolant residue from engine bay components
3. Ensure radiator cap and reservoir cap are securely installed

Verification

• Start engine and verify no coolant leaks from drain plug, bleeder screw, or hoses
• Confirm cooling fans cycle on when engine reaches operating temperature
• Check that heater produces hot air at idle and under acceleration
• Verify coolant level remains stable in reservoir at MAX line after multiple heat cycles
• Monitor coolant level over the next few days and top off if needed as air continues to purge from system

More procedures for this vehicle