Bleeding the brake system (Honda Civic 6)

Contents: Models with ABS ⇊ All models ⇊

Warning! Bleed the brake system wearing protective glasses. If brake fluid accidentally gets into your eyes, rinse them immediately with plenty of water and seek medical help!

Note: Bleeding the hydraulic system is performed to remove air that gets into the system when servicing the brake mechanisms, replacing hydraulic lines or the master cylinder, or when the fluid level in the master cylinder reservoir drops below the minimum permissible value.

1. If air has entered the system due to a drop in the fluid level in the master brake cylinder reservoir, or when the brake lines are disconnected from the master brake cylinder, the brake mechanisms of all four wheels must be bled. When disconnecting the lines from any of the calipers/wheel cylinders, it will be sufficient to bleed only that specific brake mechanism.

2. If the brake line was disconnected from the nipple located between the brake master cylinder and one of the brake mechanisms, only this part of the brake circuit is bled.

3. Press the foot brake pedal several times with the engine off to release the residual vacuum in the brake booster. Remove the cap from the brake master cylinder reservoir, add fresh fluid to the reservoir if necessary, then place polyethylene under the cap and screw it back into place.

Note: Do not forget to regularly check the fluid level in the reservoir during bleeding. An excessive drop in the level may result in air entering the master cylinder, which will nullify all efforts and will entail the need to bleed the entire brake system.

4. With the help of an assistant, have a supply of fresh brake fluid, a clear container partially filled with brake fluid, a piece of plastic hose that fits snugly over the bleeder valve, and a suitable open-end wrench to loosen/tighten the valve.

Models with ABS

1. When replacing the brake master cylinder, or after the hydraulic fluid level in its reservoir has dropped excessively on ABS-equipped models, begin the procedure by bleeding the brake lines connected to the master cylinder. Ask an assistant to slowly press the gas pedal all the way down and hold it in the lower position. Loosen the union connections of the brake lines connected to the brake master cylinder one by one, releasing the fluid mixed with air from them. Repeat the procedure until the fluid free of air bubbles begins to be pushed out of the cylinder. Now you can proceed to bleeding the hydraulic pressure modulator.

2. To bleed the modulator, tightly fit a piece of plastic hose onto its bleed valve. Start the engine, raise the pressure in the modulator, then release the valve by 1/8÷1/4 of a turn, releasing the brake fluid mixed with air.

Caution! The hydraulic fluid in the modulator is under high pressure. Never release the bleeder valve more than 1/4 turn to avoid a sharp jet of hydraulic fluid. Stop the engine and bleed the remaining components of the brake system (see below).

Note: If the ABS warning light on the vehicle's instrument panel comes on, the procedure described in the last paragraph must be repeated.

All models

1. Slightly loosen the right rear brake bleed valve, then tighten it again so that it can be released easily and quickly during the procedure.

2. Attach a suitable plastic or rubber hose to the valve, and lower the other end into a transparent container partially filled with clean brake fluid (see accompanying illustration). The end of the hose must be completely immersed in the liquid.

3. Ask an assistant to slowly depress the foot brake pedal several times, thereby increasing the pressure in the system.

4. With the brake pedal locked in the lower position, slightly open the bleeder valve so that brake fluid begins to flow out of it. Watch for fluid to come out of the end of the hose immersed in the fluid. After a few seconds, when the pressure weakens, close the valve and allow the assistant to release the pedal.

5. Repeat the procedures of the last two paragraphs until the fluid starts to flow out of the valve free of air bubbles, then move on to the left front brake mechanism. Proceed in a similar manner to bleed this mechanism, then the mechanisms of the left rear and right front wheels.

Attention! Always make sure that the fluid level in the master cylinder reservoir does not drop too low!

6. Never add old brake fluid to the reservoir – it is highly hygroscopic and over time absorbs a lot of moisture, which leads to a drop in its boiling point and, as a result, to a decrease in braking efficiency. In addition, the presence of moisture in the hydraulic system contributes to accelerated aging of the material of flexible brake hoses.

7. After bleeding is complete, add fresh brake fluid to the master cylinder reservoir, bringing its level back to normal.

8. Check the efficiency of the brakes. The pedal should provide firm resistance when pressed - the feeling of its softness indicates the presence of air in the hydraulic circuits and the need to repeat the bleeding procedure.