Checking the vacuum brake booster
For a simple test of the operation of the vacuum booster, do the following.
1. Start the engine, let it run for 1-2 minutes and stop. Depress the brake pedal several times with normal force. If the pedal goes down on the first press, but gradually rises on the second or third press, the brake booster is good. If the pedal height does not change, the booster is faulty.
2. With the engine off, depress the brake pedal several times and check for a change in pedal height. After that, press the pedal and start the engine. If at the same time the pedal goes down a little, the amplifier is working. If the pedal height remains the same, the booster is defective.
3. With the engine running, depress the brake pedal and stop the engine. Keep the pedal depressed for 30 seconds. If during this time the pedal height does not change, the amplifier is working. If the pedal rises, the amplifier is faulty.
If one of the above checks reveals a problem, check the check valve, vacuum hose, and booster and repair. If the test results are positive, the amplifier is OK.
Bleeding the system
Attention.
- Do not reuse brake fluid.
- Always use only recommended DOT 3 or DOT 4 brake fluid. The use of non-original brake fluid can lead to corrosive processes and significantly shorten the life of the brake system.
- Make sure the brake fluid is free of impurities and contaminants.
- Do not allow brake fluid to come into contact with body surfaces as this may damage the paintwork. If brake fluid gets on the body, wash it off immediately with water.
- The brake fluid level in the expansion tank must always be at the MAX mark. Check the level regularly and add brake fluid to the system if necessary.
1. Make sure that the brake fluid level in the expansion tank is at the mark «MAX».
2. Attach a vinyl hose to the bleeder on the wheel cylinder, dip the other end of the hose into a container of brake fluid.
3. Press the brake pedal several times.
4. With the pedal fully depressed, loosen the bleed screw (A) until the brake fluid starts to flow out, then tighten the fitting.
Front brakes
Rear brakes
5. Repeat steps 3 and 4 until there are no air bubbles in the escaping fluid.
6. Tighten the air bleed screw.
7. Perform the indicated operations on the remaining wheels in the order shown in the figure.
8. Fill the expansion tank of the master cylinder to the mark «MAX».