Warning: Brake fluid is poisonous. Some types of brake fluid are highly flammable. Brake fluid is hygroscopic.
Effective operation of any hydraulic system is possible only after removing all the air from it. The process of removing air from the brake system is called bleeding. When pumping, use only new, clean brake fluid. Before starting bleeding, fill the reservoir with brake fluid above the MAX mark and make sure that the brake fluid level does not fall below this mark.
On Audi 100 models not equipped with automatic rear suspension height adjustment, move the rear brake pressure control valve lever as close to the rear axle as possible and lock it in this position. Bleeding the entire hydraulic system must be carried out in the following order with the engine running.
Audi 100 models with electronic differential lock:
- bleed valve on the hydraulic module of the blocking system;
- right rear wheel brake;
- left rear wheel brake;
- right front wheel brake;
- left front wheel brake.
All other models:
- right rear wheel brake;
- left rear wheel brake;
- right front wheel brake;
- left front wheel brake.
Pumping - the main method (helper needed)
1. Remove the plastic cap from the air release valve on the first wheel brake and put the rubber tube on it. Dip the other end of the tube into a container filled with brake fluid.
2. Check that the brake fluid level in the reservoir is above the MIN·mark and have an assistant depress the brake pedal several times.
3. Open the bleed valve (about half a turn), have an assistant depress the brake pedal slowly and keep it depressed. Wait for the brake fluid to drain. When the fluid flow stops, close the valve, have an assistant release the brake pedal slowly and check the fluid level in the reservoir.
4. Repeat step 3 until there are no air bubbles in the escaping brake fluid.
5. Tighten the bleed valve securely, remove the tube and replace the cap.
6. Repeat the pumping operation on the brakes of the remaining wheels in the required sequence.
Bleeding Using the One Way Valve Kit
1. A one-way valve is installed in the rubber tube of this kit, preventing air and old brake fluid from entering back into the brake system. The kit may also include a container for collecting old brake fluid.
2. After connecting the kit to the bleed valve, open the valve. Gently depress the brake pedal and release it slowly. Repeat this operation until all air is removed from the brake system.
Bleeding Using a Pressure Bleeding Kit
By connecting the pressure bleeding kit to the brake fluid reservoir, to bleed the system, simply open the bleed valves in turn to drain the old brake fluid and bleed the air.
All Methods
After bleeding is complete, wash off any spilled brake fluid, tighten the bleed valves securely, and refit the caps. Check the brake fluid level again.
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