Contents: General description ⬇ Pumping sequence ⬇ Pumping is the main method (for two…⬇ Bleeding with a non-return valve…⬇ Pumping under pressure ⬇ All methods ⬇
Note: Brake fluid is poisonous. Rinse any parts of your body that come into contact with the fluid with plenty of cold running water and seek immediate medical attention if the fluid gets into your mouth or eyes. Some types of brake fluid are flammable and may ignite when in contact with hot components. Take appropriate fire safety measures. Brake fluid is aggressive to paint and plastics - if it comes into contact with such surfaces, rinse the fluid off immediately with plenty of water. In addition, the fluid is hygroscopic (absorbs moisture from the air) - old fluid may be contaminated with water and unsuitable for use. When adding fluid to the system or replacing it, use the recommended type of fluid, pouring it from a freshly opened sealed container.
General description
1. The correct functioning of the brake hydraulic system is possible only if its components are free of air. To remove air from the system, bleed it.
2. During the bleeding procedure, add only clean, fresh brake fluid of the specified grade Specifications type. Never reuse liquid. Make sure you have enough liquid before you start working.
3. If there is any doubt about the type of fluid in the system, flush the system with clean fluid and replace all seals.
4. If the brake fluid level in the master cylinder has dropped, find and repair the cause of the leak before continuing.
5. Park the car on a level place (not downhill), turn off the ignition and select 1st gear or reverse. Block the wheels and release the handbrake.
6. Make sure all tubes and hoses are securely attached, couplings are tight, and bleed nipples are closed. Remove dust caps and clean dirt from nipples.
7. Unscrew the cap of the brake hydraulic system replenishment reservoir and bring the fluid level to the "MAX" line. Screw the cap on and do not forget to maintain the fluid level above the "MIN" line throughout the procedure, otherwise air will get into the system again.
8. There are a number of devices available for one-person bleeding of the brake system. It is recommended to use one of these kits as they make the job much easier and also reduce the risk of air and fluid being sucked back into the system. If such a device is not available, use the basic bleeding method (for two people), described in detail below.
9. If using a tool, prepare the vehicle as described above and follow the kit manufacturer's instructions. The procedure may vary slightly depending on the type of tool used, but the basic procedure is also described below.
10. Whatever method you use, follow the correct pumping sequence.
Pumping sequence
11. If components of only one circuit have been disconnected or removed (for example, a caliper or a wheel cylinder) and measures were taken to minimize fluid loss; only this brake unit needs bleeding.
12. If the entire system needs to be bled, proceed in the following sequence:
- a) Right front brake.
- b) Left rear brake.
- c) Left front brake.
- d) Right rear brake.
13. On all vehicles equipped with pressure-sensitive brake pressure control valves (i.e. except for Pickup models), bleeding the rear brakes may take longer due to the valves restricting the working area of the system.
Pumping is the main method (for two people)
14. Prepare a clean glass container and a suitable length of plastic or rubber tube that fits tightly onto the bleed nipple. You will need the help of a second person.
15. If not already done, remove the dust cap from the bleed nipple and place the prepared tube on the nipple. Immerse the other end of the plastic tube in the brake fluid previously poured into the reservoir.
16. Make sure the master cylinder reservoir is full and maintain the fluid level above the "MIN" line throughout the procedure.
17. Ask an assistant to press the brake pedal all the way down several times (to relieve the vacuum), and then hold it down.
18. While the pedal is depressed, loosen the bleed screw approximately one turn. When fluid stops flowing from the screw, tighten it and have an assistant slowly release the pedal. Check the fluid level in the reservoir again.
19. Repeat this procedure (points 17 and 18), until the escaping brake fluid is free of air bubbles. If the entire system is bled, allow at least five seconds between cycles on the first brake unit to allow the fluid to fill the master cylinder channels (see also point 24 Chapters 11).
20. Tighten the bleed nipple, remove the plastic tube and install the dust cap. Do not overtighten the nipple.
21. Repeat the procedure on the remaining brake assemblies in the sequence indicated above.
Bleeding with a non-return valve device
22. These devices consist of a tube with a non-return valve that prevents air and liquid that has escaped from it from being drawn back into the system. Some kits also include a transparent container (see photo).
23. Attach the tube to the bleed nipple and open it. Press the brake pedal slowly and smoothly, then release it slowly. Repeat this action until the fluid coming out of the nipple is free of air bubbles.
24. These kits make the job so easy that it's easy to forget about draining the master cylinder reservoir. Check the fluid level in the reservoir periodically and keep it at least above the "MIN" line.
Pumping under pressure
25. These devices are operated by compressed air contained in the spare tire chamber. However, note that the air pressure must be reduced (see instructions included with the device).
Data taken from an online portal SkodaBook.ru
26. Attach the supplied container filled with brake fluid to the master cylinder reservoir and to the spare tire. Bleed by opening the nipples one by one (in the given sequence) and draining the liquid until it is free of air bubbles.
27. This method has the advantage that the large amount of fluid in the installed reservoir prevents air from entering the master cylinder during bleeding. On all vehicles equipped with pressure-sensitive brake pressure control valves (i.e. except for Pickup models), the pressure in the spare tire chamber should be as low as possible (however, it is still effective for pumping), otherwise the valves may be triggered, making it difficult to bleed the rear brake assemblies.
28. Bleeding under pressure is especially effective when bleeding "problem" systems (the airlock is stuck in a place where it is difficult to get out) or when completely bleeding the system during the next fluid change.
All methods
29. When bleeding is complete, wash away any spilled fluid, tighten the bleed nipples and install their dust caps.
30. Check and top up the liquid level in the feed tank (see Section 1).
31. Pour out the brake fluid that comes out during bleeding - it is not suitable for reuse.
32. Check the elasticity of the brake pedal. If you feel dips when moving it, there is still air in the system and further bleeding is required. If repeated bleeding does not bring a satisfactory result, the master cylinder seals may be worn out.