Changing a timing belt on a Honda Civic before it wears out is critical. Damage will occur if the timing belt wears down enough to break while the car is running. Honda Civics require the timing belt to be changed every 105,000 miles. It's a good idea to change the timing belt before the car reaches this point to avoid damage.
Remove the wheel on the front driver's side of the car.
Remove the black plastic protective shield under the car on that side.
Set the car on jack stands, one on each side of the car under the frame.
Mark the plugs and terminals to indicate the order, and remove the spark plug cover and spark plugs using the extension on the ratchet to reach them. Remove the valve cover after removing the plug wires.
Loosen the pivot bolt of the power-steering pump belt and then the pinch bolt, which is beneath the pivot bolt. Swing the pump out until the belt can be removed. Do the same steps with the alternator until the belt is removed.
Place a jack directly underneath the engine on the driver's side. Put a block of wood on top of the jack and then slowly raise it up until it is resting on the oil pan and holding the weight of the engine.
Remove the engine mount on that side so you can reach and remove the upper timing belt cover.
Turn the crank until the distributor rotor is aimed at the No. 1 you marked on the distributor cap. This means the first piston has reached Top Dead Center (TDC) and is aligned correctly to install the new timing belt.
Remove the starter and place a screwdriver between the flywheel and the bell housing so the crank doesn't move.
Unscrew the crank bolt using a ratchet and socket. Remove the crank pulley and Woodruff key. This is very small and should be placed in a safe container.
Remove the lower timing belt cover, loosen the timing belt tensioner and remove the timing belt.
Install the new timing belt, keeping the "up" mark on the camshaft sprocket at the top. The timing mark on the crank sprocket should remain pointed at the arrow on the oil pump.
Reverse the steps until everything is replaced exactly as it was.
Remove the jack stands and lower the car. Start the car to make sure the engine sounds right.
Make sure you complete every step when putting the car back together.
If the plugs are replaced in the wrong order, the car will not fire correctly--possibly not at all.