Table of contents: Pumping - a method for two ↓ Bleeding - with a one-way valve kit ↓
Note: On models equipped with anti-lock brakes, refer to Chapter 28 before starting work
1. Correct functioning of the brake hydraulic system is possible only after all air has been removed from the components and circuit; this is achieved by pumping the system.
2. Brake system pipes and components must be completely flushed with clean fluid.
3. Never reuse brake fluid.
4. When performing the procedure, do not allow the brake fluid level to fall below the middle of the reservoir.
5. Before starting work, check that all pipes and hoses are not damaged, connections are tight and bleed nipples are closed.
6. Bleeding can be done with an assistant, or independently using a brake system bleeding kit. Always follow the instructions. It is recommended to use a kit wherever possible, as they greatly simplify the bleeding procedure. If there is no bleeding kit, you need to stock up on a clean flask and a transparent plastic tube of suitable length, which should fit tightly onto the bleeding nipple, and you will also need the help of another person.
7. If brake fluid has been lost from the master cylinder due to a leak in the system, find the cause and repair the leak before proceeding.
8. If the hydraulic system has been partially disconnected and appropriate precautions have been taken to prevent further fluid loss, only part of the system may be bled.
9. If a complete bleeding of the system is required, perform it in the following sequence:
- 1) Right rear wheel cylinder or brake caliper.
- 2) Left rear wheel cylinder or brake caliper.
- 3) Right front brake caliper.
- 4) Left front brake caliper.
Note: If the system has leaked after removing and installing the master cylinder, the clutch system on models with a hydraulically controlled clutch must also be bled. This must be done as described in Section 5.
10. To bleed the system, first clean the area around the bleed nipple and install the tube. If necessary, add brake fluid to the master cylinder reservoir.
11. If the system has a vacuum booster, release the vacuum by quickly depressing the brake pedal.
Pumping - a method for two
12. Prepare a clean bottle and a long rubber or plastic tube that can be placed on the brake bleed nipples.
13. Use the help of a second person.
14. Place one end of the tube on the first bleed nipple, lower the other end into a bottle, which should contain enough hydraulic fluid so that the end of the tube is recessed into it.
15. Open the bleed screw half a turn, fully depress the brake pedal, then slowly release it. Squeeze the bleed screw at the end of each pedal stroke until it stops.
16. Repeat this action until clear liquid without air bubbles flows into the flask.
17. Clamp the bleed nipple at the end of the bottom pedal stroke and remove the pipe.
Bleeding - with a one-way valve kit
18. It is recommended to use the kit wherever possible, as it greatly simplifies the pumping procedure.
19. Connect the pipe to the bleed nipple, open the nipple half a turn.
20. Press the brake pedal fully and release slowly. The one-way valve in the kit will prevent any air that has escaped from the system from escaping back at the end of each pedal stroke until the bottom stop. Repeat this several times to ensure that all air has been removed from the system. Some kits have a translucent container that can be positioned so that air bubbles escaping from the system are visible.
21. Clamp the bleed nipple, remove the pipe, repeat the steps on the remaining brakes.
22. Finally, press the brake pedal. If you still feel dips, repeat the bleeding.
Bleeding - with a pressure bleeding kit
23. These kits usually operate off the air pressure of the spare tire.
24. With a sealed container connected to the master cylinder reservoir, bleed the fluid by simply opening each bleed nipple in turn and allowing fluid to flow out until there are no air bubbles.
25. When bleeding using this method, a large amount of hydraulic fluid is required to prevent air from entering the master cylinder during bleeding, which often occurs if the fluid level in the reservoir is not maintained.
26. Pressure bleeding is especially effective when the system is "difficult" to bleed or when a complete system bleeding is performed during a normal fluid change.
All methods
27. After bleeding, check and top up the fluid level in the master cylinder reservoir.
28. Check the brake pedal operation. If there are dips, there is still air in the system and it needs to be bled again. The failure may be due to worn out master cylinder seals.
29. The removed brake fluid should not be used again. Clean fluid should be stored in an airtight container (hermetically sealed) container, as it is very hygroscopic (absorbs moisture well), this lowers the boiling point and worsens the technical characteristics.