2. Stop the engine.
3. Depress the brake pedal with force, as during normal braking.
4. If the pedal travel is large during the initial pressing, and the pedal travel decreases with subsequent pressing, then the brake booster is working.
If the tightness is broken, check the tightness of the following components:
- stop valve (built into the vacuum hose).
- Vacuum tubes and hoses.
- Brake booster.
- Cuffs of the primary and secondary pistons of the master cylinder.
5. Start the engine again.
6. Depress the brake pedal with force, as during normal braking.
7. In this state, turn off the engine.
8. Keep the brake pedal depressed for approx. 30 sec. If the brake pedal height does not change, then the system is tight.
Checking tightness with a special tool
1. Using a suitable hose, connect the vacuum gauge (special tool) between the brake booster and the stop valve.
2. Start the engine and warm up until the fan operates twice. Depress the accelerator pedal until a vacuum of 66.7 kPa is created (500 mmHg Art.), and stop the engine.
3. Read the vacuum gauge reading.
- Standard vacuum reduction in 15 sec: 3.3 kPa (25 mmHg Art.)
4. If the tightness is broken, check the tightness of the following components.
- check valve (built into the vacuum hose)
- Vacuum tubes and hoses
- brake booster
- Cuffs of primary and secondary pistons of the main cylinder
Function test
1. Install special tools on the master cylinder as shown.
2. Purge air through the special tool bleed valves.
3. Start the engine and warm up until the fan operates twice.
4. Depress the brake pedal with the force given below and measure the brake fluid pressure at the outlets when the vacuum gauge reads 0 kPa (0 mmHg Art.) (does not enhance) and 66.7 kPa (500 mmHg Art.).
Check valve
The check valve is integrated into the brake booster vacuum hose. If the hose passes air when blown in from the side of the brake booster and does not pass when blown in from the reverse side, then the valve is working.