Contents: Checking for leaks ⇊ Checking the operation of the brake…⇊ Checking the brake booster check…⇊
Checking for leaks
1. Connect vacuum gauge A between the vacuum booster and the check valve.
2. Start the engine, press the accelerator pedal until the engine speed reaches a level where the vacuum after the throttle valve is 66.7 kPa, then turn off the engine.
3. Read the vacuum gauge readings.
If the vacuum decreases by 2.7 kPa or more within 30 seconds, the following system components must be checked for leaks:
- check valve;
- vacuum hoses, pipelines;
- seals;
- brake booster;
- master brake cylinder.
Note: The brake booster cannot be disassembled or repaired. If the brake booster is faulty, it must be replaced.
Checking the operation of the brake booster
1. Connect the vacuum gauge in the same way as during the leak test.
2. Connect the fluid pressure gauges A to the brake master cylinder using the T-fittings as shown in the figure.
3. Remove air through air bleed valves B.
4. Start the engine and let it idle.
5. Ask an assistant to press the brake pedal. The assistant should press the pedal with a force of 98 N and 294 N on the pressure gauge scale A.
6. The readings of the measuring pressure gauges at different values of vacuum in the intake tract should be as follows.
VSA
7. If the brake fluid pressure after the master cylinder is less than the values given in the table, then the tightness of the sealing cuffs of the master cylinder should be checked.
Checking the brake booster check valve
1. Disconnect the brake booster hose (a check valve is built into it) And from the brake booster.
2. Start the engine and let it idle. You should feel air leaking from the open end of the vacuum hose. If there is no air leak, the check valve is faulty. Replace the vacuum line together with the check valve and repeat the test.