- A) Brake fluid is poisonous. Under no circumstances should it be sucked out by mouth through a hose. Brake fluid should only be poured into containers that prevent human misuse.
- b) Brake fluid is corrosive, so it must not come into contact with car paint. If brake fluid comes into contact with painted surfaces, remove it immediately and wash the surface with plenty of water.
- V) Brake fluid is hygroscopic, which means it absorbs moisture from the air, lowering its boiling point. Therefore, store brake fluid only in closed containers.
- G) Brake fluid is flammable. Store it in a closed container at room temperature.
- d) Brake fluid that has already been used once in the brake system must not be refilled. When removing air from the brake system, fill in only new brake fluid.
- e) Brake fluid specification: SAEJ 1703 and DOT 4.
- and) Brake fluid must not come into contact with petroleum products. Even small impurities of petroleum products make the brake fluid unusable or lead to failure of the brake system. Plugs and cuffs of the brake system become unusable when in contact with products containing petroleum products. When cleaning, do not use rags impregnated with petroleum products.
- h) Before removing the caps from the brake fluid container and from the expansion tank, they must be cleaned of dirt. The same applies to the bleeder fittings.
- And) The brake fluid must be changed every 2 years, if possible after the cold season.
After any brake repair that opens the brake system, air can enter the pressure lines. In this case, it is necessary to remove this air from the brake system.
The presence of air in the pipelines can also be judged by the fact that when you press the brake pedal, no strong resistance is felt. In this case, it is necessary to eliminate the leakage and remove air from the system.
In workshops, air is removed from the system using a device for filling brake fluid and bleeding the brake system.
Bleeding with this device is recommended in cases where one of the brake hoses was dismantled, one of the chambers of the expansion tank was emptied, or if it is necessary to bleed the clutch hydraulic drive.
In other cases, bleeding can be done in the usual way by depressing the brake pedal. An assistant is needed for this operation.
If you need to bleed the entire system, then you need to remove air from each brake mechanism. This happens when air has entered all the working brake cylinders. If only one brake caliper or only one working brake cylinder has been replaced or rebuilt, it is generally sufficient to bleed only the corresponding brake mechanism.
If air has entered the ABS hydraulic unit, it is recommended to have the air removed by a specialist workshop. This can happen in the event of a depressurization of the ABS hydraulics or in the case when brake fluid has completely leaked out of at least one chamber of the expansion tank and, as a result, air has been pumped into the system. Air ingress is also possible due to carelessness when removing air from the system, when the volume of brake fluid was not replenished in time and air was sucked in.
Air removal sequence:
- A) rear left wheel brake
- b) front right wheel brake
- V) rear right wheel brake
- G) front left wheel brake.
Attention! Loosen the brake bleeders carefully so as not to strip the threads. It is recommended that a rust remover be applied to the fittings one hour prior to air removal work. If they do not turn away, then this work should be entrusted to the workshop.
Attention! At the bleed inlet, hold a container to collect the brake fluid about 30 cm above the bleeder port and check the brake fluid level in the expansion tank from time to time. The level of brake fluid in the reservoir must not be allowed to drop to the limit or that the reservoir was at all «devastated». In this case, air will be pumped into the system. Top up the amount of brake fluid in the expansion tank!
1. Remove a protective cap from the union of prorolling of the working brake cylinder. Clean the fitting, put a clean hose on it, lower the other end of the hose into a container half filled with brake fluid (see illustration). The appropriate hose and container are available from auto parts stores.
The assistant must constantly press the brake pedal to the end («sway»), until pressure builds up in the brake system. It is felt by increasing the resistance to pressing the pedal.
After sufficient pressure is obtained, press the pedal all the way down and hold it in this position.
2. Unscrew 1 bleed valve located on the caliper with a key, approximately half a turn. Collect escaping brake fluid in a container. Make sure that the end of the hose in the container is constantly below the liquid level (see illustration).
3. Close the fitting as soon as the brake fluid pressure decreases.
4. Repeat pumping until pressure appears. Press the brake pedal down to the stop, leave your foot on the pedal. Open the bleed valve and, after reducing the pressure, close the valve.
5. Repeat pumping on one caliper until air bubbles no longer appear in the liquid flowing into the container.
6. After removing the air, remove the hose from the bleeder and close it with a dust cap.
In the same way, remove the air from the brake cylinders of other wheels, while observing the bleeding sequence.
7. Bring after removal of air level of a brake liquid in a broad tank up to the maximum mark.
8. Depress the brake pedal with the engine off. The pressure in the brake system must not be «loose». If this is the case, then repeat the procedure for bleeding the brake system.
Attention! Make sure that:
- A) brake hoses are securely connected,
- b) the brake hose is fixed in the holder,
- V) brake bleeders are screwed on,
- G) there is enough brake fluid in the expansion tank.
9. Carry out a leak test of the brake system with the engine running.
To do this, depress the brake pedal with a force of 200-300 N (20-30 kg) for approximately 10 seconds. The pressure in the system and, accordingly, on the brake pedal, must not fall. Check all connections for tightness.
10. Perform test braking on a light road. At the same time, hard braking must be performed at least once in order for the ABS to turn on. Its action will be felt by a slight pulsation of the brake pedal.
Attention! When braking, make sure that there is no passing vehicle behind you.
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