How to Replace a Thermostat in a 2001 Honda Civic

by Dan Ferrell

The thermostat in your 2001 Honda Civic has a small, wax-filled cylinder in the middle. When hot, the wax expands and opens the thermostat, letting hot coolant from the engine flow into the radiator to remove heat. With years of service, this mechanism fails, blocking or allowing coolant to flow freely and permanently. Either way, engine performance is compromised. However, stuck coolant will cause the engine to overheat and, given enough time, melt internal components. Replace the thermostat as soon as possible in your Honda Civic and prevent expensive repairs down the road.

Removing the Old Thermostat

Step 1

Place a clean drain pan under the radiator in the direction of the drain valve. Insert one end of a 12-inch clear, vinyl hose into the drain valve and point the other end to the drain pan.

Step 2

Loosen the radiator cap and open the drain valve by hand. Allow the coolant to drain completely. Close the drain valve and remove the hose. Cover the drain pan to keep the coolant clean for later reuse.

Step 3

Shift the transmission to Neutral and release the parking brake. Jack up the front of your Honda Civic with a floor jack. Place a jack stand under each side for support. Chock the rear wheels.

Step 4

Put on a pair of safety goggles. Crawl under the front of your Civic and remove the engine splash shield from the bottom with a ratchet and deep socket.

Step 5

Depress the clamp tabs holding the lower radiator hose to the thermostat housing at the engine side. Slide the clamp about five inches toward the radiator with a pair of rib-joint pliers. Pull the lower radiator hose off the thermostat housing by hand.

Step 6

Unfasten the two bolts (1.7L engine) or three bolts (2.0L engine) securing the thermostat housing to the engine with a ratchet, short ratchet extension and deep socket.

Step 7

Separate the thermostat housing from the engine. Remove the O-ring seal and thermostat from the engine opening. Look at the mounting position of the thermostat, if you are working on a 1.7L engine.

Installing the New Thermostat

Step 1

Clean the engine block opening and thermostat housing mating surfaces with a plastic scraper, if necessary. Position the new thermostat in place with the pointed side toward the thermostat housing and install a new O-ring seal. On the 1.7L engine model, make sure the pin located on one side of the thermostat is at the 12 o'clock position.

Step 2

Replace the thermostat housing and install the two bolts (1.7L engine) or three bolts (2.0L engine) finger-tight to secure the thermostat housing to the engine. Tighten the bolts to 9 ft.-lbs. (12 Nm) on the 1.7L engine or 7 ft.-lbs. (10 Nm) on the 2.0L engine with a torque wrench, short ratchet extension and deep socket.

Step 3

Replace the lower radiator hose on the house thermostat fitting. Secure the hose to the housing with the clamp using the rib-joint pliers.

Step 4

Reinstall the engine splash shield with the ratchet and deep socket.

Step 5

Raise your Honda Civic above the jack stands. Remove the jack stands and lower the car to the ground. Apply the parking brake and remove the chocks from the rear wheels.