Safety note
Brake fluid is poisonous. Never suck out brake fluid by mouth through a hose. Pour brake fluid only into containers from which accidental consumption is excluded.
- Brake fluid is caustic and must therefore not come into contact with car paint, otherwise wipe it off immediately and rinse the contact area with plenty of water.
- Brake fluid is hygroscopic, meaning it absorbs moisture from the air. Therefore, store brake fluid only in closed containers.
Caution: Make sure that children do not accidentally drink brake fluid.
- Brake fluid that has already been used in the brake system must not be reused. When bleeding the brake system, also use only new brake fluid.
- Brake fluid specification: FMVSS 116 DOT 4.
Note: The brake fluid level in the reservoir must always be between the MAX and MIN·marks.
- Brake fluid must not come into contact with mineral oils. Even slight traces of mineral oil make the brake fluid unusable or lead to failure of the brake system. Plugs and cups of the brake system are damaged if they come into contact with products containing mineral oils. Do not use cleaning cloths with traces of mineral oil.
- Change the brake fluid every 2 years, if possible after the cold season.
Caution: Brake fluid is a problematic material, so never dump it on the ground or dispose of it with household waste. Municipal authorities should inform where the nearest collection points for special waste are located.
Air removal
After each repair of the brakes, in which the hydraulic system was opened, air could enter it. This air must be removed from the brake system. If there is air in the brake system, the brake pedal will lightly when pressed «fails». In this case, it is necessary to repair the leak and remove air from the brake system.
At service stations, filling the brake system with liquid and removing air from the system is usually done using a special device. The use of an air bleeder is prescribed in cases where the brake hose has been removed or when at least one of the chambers of the expansion tank is completely empty. In this case, we are talking about performing an operation without this device. Air from the brake system is removed by pumping it with the brake pedal; an assistant is required to complete this work. If air must be removed from the entire system, then for this it must be removed from each wheel brake cylinder and from the clutch slave cylinder. This must be done whenever air has entered each wheel brake cylinder. However, if only one brake caliper has been repaired or replaced, it is generally sufficient to bleed only the corresponding wheel brake cylinder.
Safety note for vehicles with ABS
If one chamber of the brake fluid reservoir is completely empty (for example, as a result of a leak in the brake system or the chamber was not replenished in a timely manner when filling the system with brake fluid), air enters the system and reaches the ABS hydraulic pump. In this case, bleeding from the brake system must be carried out at a workshop using a bleeder. If the vehicle is equipped with an EDS system, the basic adjustment must also be carried out using the diagnostic tool. When installing a new brake hose, bleeding from the system must also be carried out using a tool.
The sequence of operations when removing air: 1 - front left brake caliper; 2 - front right brake caliper; 3 - rear left brake caliper; 4 - rear right brake caliper.
Raise the car on the goats.
Before bleeding, unscrew the expansion tank cap, set it aside and add new brake fluid to the MAX mark.
Attention: Carefully, so as not to collapse, open the valve to remove air. Approximately 2 hours prior to venting, it is recommended to treat the valve with a rust converter. If the bleed valve does not open, the bleed operation must be carried out by a workshop.
Attention: Install or hold a container for draining the old brake fluid at least 30 cm above the air bleed valve and observe the brake fluid level in the compensation tank. The liquid level must not fall too low, otherwise air will be sucked through the expansion tank. Always top up with new brake fluid!
For a vehicle without ABS, but equipped with a mechanical brake force regulator (option for export), the brake force regulator lever should move when the air is bled from the rear wheel brakes.
Remove the dust cap from the brake cylinder bleed valve. Clean the bleeder valve, put a clean hose on it, insert the other end into a vessel half-filled with brake fluid (a suitable hose and container can be purchased from an automotive supply store).
Ask an assistant to press the brake pedal (pump up) until pressure builds up in the brake system. This is felt by the increasing resistance as the pedal is depressed.
If sufficient pressure is reached, press the pedal to the stop and hold it with your foot.
Open the bleeder valve on the brake caliper with a ring spanner about half a turn.
Collect escaping brake fluid in a container. Ensure that the end of the hose in the container is always below the liquid level in this container.
Close the bleed valve as soon as the brake fluid pressure drops.
Repeat the process of pressurizing with the brake pedal until the pressure rises again. Press and hold the brake pedal with your foot, open the bleed valve until the brake fluid pressure drops, then close the bleed valve.
Repeat the process of removing air from the brake cylinder until air bubbles stop flowing together with the brake fluid that flows into the container.
After venting, remove the hose from the valve and put the dust cap on the valve.
Similarly, remove air from the brake cylinders of other wheels, adhering to the order described above.
After removing the air, top up the brake fluid level in the expansion tank to the MAX mark.
Attention, perform a security compliance check:
- Are the brake lines tight?
- Is the brake hose in the holder?
- Are the bleed valves tight?
- Is there enough fluid in the brake system?
- With the engine running, perform a leak test. To do this, act on the brake pedal with a force of 200 to 300 N for about 10 seconds (from 20 to 30 kg). Do not loosen the brake pedal. Check all connections for tightness.
Finally, perform a few stops on a street with little traffic. At the same time, at least one hard braking must be undertaken with the ABS functioning (the functioning of the system is recognized by the pulsation of the brake pedal).
Attention: Before braking, make sure there are no vehicles behind.
Caution: Old brake fluid is problematic material and should never be dumped on the ground or disposed of with household waste. The administration of districts and cities should inform about where the nearest points for receiving special waste are located.
Visitor comments