How to Install a Thermostat on a Honda Civic

The thermostat on your Honda Civic is a very effective component of the cooling system. However, once its thermal mechanism fails and stops regulating engine temperature, it needs to be replaced to prevent engine overheating or under temperature operation. You may install a new thermostat yourself using a few common tools. Once you have the exact replacement for your particular model, follow this guide to replace the unit on your Honda.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Drain pan
• Floor jack and 2 jack stands
• Wrench set
• Ratchet and socket set
• Phillips screwdriver
• Rib joint pliers
• New anti-freeze

Removing the Thermostat

1. Place a drain pan under the radiator drain valve and remove the radiator cap.

2. Open the radiator drain valve and remove at least 2 quarts of coolant. Then, close the drain valve.

3. Raise the front of the vehicle using a floor jack and safely support it on two jack stands.

4. Remove the splash shield from the underside of the engine using a wrench or ratchet and socket.

5. Disconnect the lower radiator hose at the thermostat housing on the engine side. Use a Phillips screwdriver, rib joint pliers or ratchet and socket, depending on clamp type used on your particular Honda Civic.

6. Unscrew the three thermostat housing mounting bolts using a ratchet and socket.

7. Remove the thermostat housing, thermostat unit and O-ring or rubber seal.

Installing the Thermostat

8. Set the new thermostat in place along with a new O-ring or rubber seal.

9. Install the thermostat housing and start the three mounting bolts by hand to avoid damage to the threads. Then tighten the mounting bolts.

10. Connect the lower radiator hose to the thermostat housing and tighten the clamp.

11. Re-install the splash shield to the underside of the engine.

12. Refill cooling system with 50 percent water and 50 percent of new anti-freeze.

13. Replace the radiator cap. If your particular Honda Civic model comes equipped with a bleeding screw or valve on the thermostat housing, bleed the cooling system according to the next section.

Bleeding the Cooling System

14. Start the engine and let it idle for three minutes.

15. Loosen the bleed screw on the thermostat housing using a wrench or ratchet and socket, just enough to let the air bleed through.

16. Tighten the bleed screw when coolant begins to leak through the bleed screw.

17. Turn the engine off.

18. Wait about 15 minutes to let the engine cool down and add coolant to the reservoir tank. Make sure the level reaches between the Low and Full marks.

Tips & Warnings

• Some specific Honda Civic models may have more than one bleed screw to bleed the cooling system properly. Consult your vehicle owner's manual or with your local dealer for more information.
• Always store coolant in a closed container and dispose of it properly. The sweet taste of ethylene glycol in antifreeze may attract cats, dogs and even young kids with fatal results. Removing the radiator or coolant reservoir cap in a hot engine may blow coolant out and cause severe burns or injuries. Makes sure the coolant is under low temperature before removing the radiator or reservoir tank cap.

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