Attention! Brake fluid is poisonous. In case of contact with skin, wash immediately and thoroughly. If swallowed or in contact with eyes, seek medical attention immediately. Some brands of fluid are flammable and may ignite the brake fluid if it comes into contact with hot components. When servicing any hydraulic system, it is safer to assume that the fluid is flammable and take appropriate fire fighting measures (like you're dealing with gasoline). Brake fluid is an effective paint thinner. It eats away plastic. In case of splashing of liquid on the body paintwork or plastic elements, the affected area should be immediately washed with plenty of cold water. Finally, brake fluid is hygroscopic (can absorb moisture from the air), and therefore the used fluid may be contaminated and unsuitable for subsequent use. When topping up or replacing fluid, be sure to use the recommended brand of fluid. The liquid container should be opened immediately before use.
Models without ABS
General information
1. The correct operation of any hydraulic system is possible only after the complete removal of air from the elements and the circuit. This is achieved as a result of the procedure for removing air from the system (pumping system).
2. When bleeding the system, add only clean, unused brake fluid of the recommended brand (see «Lubricants and operating fluids»). Never reuse fluid drained from the system. Before starting the procedure, check if you have enough fresh fluid.
3. If there is even the slightest chance that the wrong brand of fluid is present in the system, the elements and circuit of the brake system should be thoroughly flushed with a clean fluid of the appropriate brand. After that, the seals in all elements of the system should be replaced.
4. If brake fluid leaked from the system or air entered the system due to a leak, correct the cause of the problem before proceeding.
5. Park the vehicle on a level surface, place wheel chocks under the wheels and release the parking brake.
6. Check the reliability of fastening of all pipelines and hoses, the tightness of the union connections and check whether the air release screws are tightened. Remove dirt from the areas around the screws.
7. Turn off a cover of a reservoir of a hydraulic drive of brakes and refuel a reservoir up to the maximum mark. Replace the cover, but do not tighten it. Do not forget to maintain the fluid level below the minimum mark throughout the procedure. Otherwise, air may enter the system again.
8. There are a variety of bleed kits available for individual do-it-yourself work. They are sold at auto supply stores. It is recommended to use one of these kits whenever possible, as this greatly simplifies the bleeding procedure and reduces the risk of re-introduction of air and removed brake fluid into the system. If you do not have such a kit, use the main method (with an assistant), a detailed description of which is given below.
9. If you still decide to use the kit, prepare the car as described above. Then follow the kit manufacturer's instructions, as procedures may vary slightly depending on the type of accessory being used. A general description of the techniques is given below in the relevant part of the paragraph.
10. Whichever method is used, the same sequence of steps must be followed to ensure complete removal of air from the system (p.p. 11 and 12).
Bleeding sequence
11. If only part of the system has been disconnected and appropriate precautions have been taken to minimize brake fluid leakage, only part of the system will need to be bled (e.g. from primary or secondary circuit).
12. If air is to be removed from the entire system, the procedure must be carried out in the following sequence:
- A) right rear brake
- b) left rear brake
- V) right front brake
- G) left front brake.
Basic way (with an assistant)
13. Prepare a clean glass beaker. a suitable piece of plastic or rubber tubing that can fit snugly over the air outlet screw, and a box wrench for the screw. In addition, you will need an assistant.
14. Remove the dust cap from the first bleed screw in the sequence. Place the wrench and tube on the screw and lower the other end of the tube into the glass. Pour brake fluid into the glass so that it covers the end of the tube.
15. Make sure that during the entire procedure the fluid level in the brake fluid reservoir remains at least above the MIN·mark.
16. Ask an assistant to fully depress the brake pedal several times to increase the pressure, and on the last stroke to leave the pedal depressed.
17. While the assistant continues to hold the pedal down, loosen the air release screw (about one turn) and allow the pressurized liquid with air bubbles to drain into the beaker. The assistant should continue to press the pedal, pushing it to the floor if necessary, and should not release it until he has been instructed to do so by you. When the fluid stops flowing, re-tighten the bleed screw, have an assistant slowly release the pedal and check the fluid level in the reservoir.
18. Repeat the steps in p.p. 16-17 until the brake fluid that does not contain air bubbles comes out of the bleed screw. If the master cylinder has been emptied and refilled and air is still escaping from the first screw in the above sequence, pause approximately five seconds between cycles to allow the master cylinder passages to refill.
19. When no more air bubbles are visible, tighten the air bleed screw securely, remove the tube and wrench, and replace the dust cap. Do not over tighten the air bleed screw.
20. Repeat the procedure for the rest of the brakes following the sequence above. Operate until all air has been removed from the system and the brake pedal is no longer felt «solid».
Using the check valve kit
21. From the name it is clear that the kit includes a piece of tube with a check valve that prevents the return of removed air and brake fluid into the system. Some kits include a translucent container that can be positioned so that air bubbles as they exit the end of the tube can be more visible.
22. Connect a tube to the air outlet screw and then loosen the screw, opening the corresponding channel. You should sit in the driver's seat and depress the brake pedal smoothly and evenly and slowly release it. This is repeated until the liquid being removed is completely free of air bubbles.
23. Keep in mind that these kits make the job so easy that you can easily forget about maintaining the required fluid level in the brake fluid reservoir. The level throughout the procedure should be maintained not below the minimum mark. Otherwise, air will again enter the system.
Using a pressurized bleed kit
24 These kits typically use the compressed air contained in the spare tire. But be aware that. most likely, you will need to reduce the tire pressure to a value less than normal. For details, refer to the instructions that came with the kit.
25. By connecting a container filled with pressurized fluid to the brake fluid reservoir, bleeding can be done by simply opening each screw in turn (in the prescribed sequence) and allowing the liquid to flow out until the air bubbles are gone.
26. This method has the advantage that the large fluid container provides additional protection against air entering the system while it is being pumped.
27. Air removal under pressure is especially effective when pumping «difficult» systems or when removing air from the entire system during a scheduled fluid change.
All ways
28. After the end of the removal of air, when the normal «feeling» pedals, clean up any spilled brake fluid, tighten the bleed screws securely, and reinstall the dust caps.
29. Check the brake fluid level in the brake fluid reservoir and top up if necessary.
30. Collect all fluid drained from the system in a suitable container and dispose of this container appropriately. The drained fluid is not suitable for reuse.
31. Check «feeling» brake pedals. If the pedal is perceived as soft, then there is still air in the system and further removal of it is required. Failure to satisfactorily bleed air after repeating the bleeding procedure may be due to worn master cylinder seals.
Models with ABS
Attention! On models equipped with ABS, turn off the ignition before starting the bleed procedure to ensure that no voltage is applied to the hydraulic modulator before the bleed procedure is completed. Ideally, the battery should be disconnected. Applying voltage to the modulator before the bleed procedure is completed will cause the brake fluid to drain from the modulator, rendering the unit inoperable. Therefore, do not try to turn on the modulator to bleed air from the brakes.
32. A pressurized bleed kit should be used to bleed the hydraulic brakes on models with ABS (see p.p. 24-27).
33. Following the sequence in step 12, perform the bleed procedure for each brake in turn, allowing the fluid to flow out until no air bubbles are present. Pause between bleeding each brake to prevent the fluid level in the reservoir from dropping below the minimum mark.
34. At the end of the removal of air and recovery «hardness» wipe off any spilled fluid, tighten the bleed screws and replace the dust caps.
35. Check the level of brake fluid in the brake fluid reservoir and top up if necessary.
36. Dispose of the fluid drained from the system; it is not suitable for reuse.
37. Check «feeling» brake pedals. If the pedal is perceived «soft», it means that there is still air in the system and it is necessary to continue the procedure for removing air.
Attention! Do not operate the vehicle if you are in doubt about the effectiveness of the braking system. If a significant amount of air was present in the system before bleeding, it is possible that some air has remained in the hydraulic modulator. If, after repeated attempts to bleed air, the pedal continues to be perceived «soft» or the brake warning lights remain on, have the vehicle towed to a Peugeot/Citroen dealer to have the air bleed using the Peugeot/Citroen diagnostic equipment.