Note: On models equipped with an anti-lock braking system, refer to Chapter 28 before starting work
1. Proper functioning of the brake hydraulic system is possible only after all air has been removed from the components and the circuit; this is achieved by pumping the system.
2. Brake pipes and components must be completely flushed with clean fluid.
3. Never reuse brake fluid.
4. When performing the procedure, do not let the brake fluid level fall below the middle of the reservoir.
5. Before starting work, check that all pipes and hoses are not damaged, the connections are pinched and the bleed fittings are closed.
6. Bleeding can be performed with an assistant, or independently with a brake system bleeding kit. Always follow the instructions. It is recommended to use the kit wherever possible, as they greatly simplify the bleeding procedure. If there is no bleed kit, stock up on a clean flask and a clear plastic tube of a suitable length, which should fit snugly over the bleed fitting, and the help of another person will also be required.
7. If brake fluid has left the master cylinder due to a system leak, 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 loss of fluid, only part of the system can be bled.
9. If a complete bleeding of the system is necessary, perform it in the following sequence:
- 1) Right rear working brake cylinder or brake caliper.
- 2) Left rear working brake cylinder or brake caliper.
- 3) Right front brake caliper.
- 4) Left front brake caliper.
Note: If there was a leak in the system after removal and installation of the master cylinder, it is also necessary to bleed the clutch system on models with a hydraulically controlled clutch. This must be done as described in Section 5.
10. To bleed the system, first clean the area around the bleeder port 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 depressing the brake pedal quickly.
Pumping - the method together
12. Get a clean flask and a long rubber or plastic tube that can be put on the brake bleeder fittings.
13. Use the help of a second person.
14. Slide one end of the pipe over the first bleeder port, dip the other end into a flask containing enough hydraulic fluid to submerge the end of the pipe.
15. Open the bleeder valve half a turn, fully depress the brake pedal, then slowly release. Squeeze the bleeder screw at the end of each pedal stroke to the bottom stop.
16. Repeat this action until clear liquid without air bubbles flows into the flask.
17. Clamp the bleeder valve at the end of the lower pedal stroke, remove the pipe.
Bleeding - one-way valve kit
18. It is recommended to use the kit wherever possible, as it greatly simplifies the bleeding procedure.
19. Connect the pipe to the bleed fitting, open the fitting half a turn.
20. Fully depress the brake pedal and release slowly. The unidirectional valve included will keep the exhausted air out of the system back at the end of each pedal stroke to the bottom stop. Repeat this a few times to ensure all air is removed from the system. Some kits have a translucent container that can be positioned to show air bubbles escaping from the system.
21. Clamp the bleeder valve, remove the pipe, repeat the steps on the remaining brakes.
22. Finally, press the brake pedal. If you still feel dips, repeat pumping.
Bleeding - Bleeding Kit
23. These kits are usually powered by the spare tire's air pressure.
24. With a sealed container connected to the master cylinder supply reservoir, bleed by simply opening each bleeder valve in turn and allowing fluid to flow out of it until there are no air bubbles.
25. When bleeding by this method, a large amount of hydraulic fluid is needed to prevent air from entering the master cylinder during bleeding, which often occurs if the fluid level in the reservoir is not maintained.
26. Pressurizing is especially effective when the system «difficult» for bleeding or when a complete bleeding of the system is being performed during a normal fluid change.
All Methods
27. After pumping, check and top up the fluid level in the master cylinder reservoir.
28. Check the operation of the brake pedal. If there are dips, then there is still air in the system and re-bleeding is necessary. The failure may be due to worn master cylinder seals.
29. Removed brake fluid should no longer be used. Pure liquid must be stored in an airtight (sealed) container as it is very hygroscopic (absorbs moisture well), this lowers the boiling point and worsens the technical characteristics.
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