A) Depress the brake pedal several times with the engine off and check that the pedal travel does not change.
b) Press the brake pedal and start the engine. If the brake pedal smoothly goes down, the vacuum booster is operational.
2. Air tightness test.
A) Start the engine and stop after one or two minutes of operation. Slowly press the brake pedal several times. If the pedal goes lower on the first press than on the second and third, the vacuum booster is sealed.
b) Depress the brake pedal with the engine running and stop it with the pedal depressed. If the distance between the floor and the depressed pedal does not change within thirty seconds, the vacuum booster is sealed.
1. Check with a tester.
A) Connect pressure gauges and vacuum gauge as shown in the figure and bleed air from the system.
b) Check tightness. Start the engine. Stop the engine when the vacuum is approximately 600 mm. rt. Art.
After stopping the engine for 15 seconds, the vacuum does not fall.
V) Check tightness without load.
Start the engine and depress the brake pedal with a force of 200 N. Stop the engine when the vacuum is approximately 500 mm Hg. Art.
After stopping the engine for 15 seconds, the drop in vacuum will be no more than 25 mm. rt. Art.
G) Checking with the amplifier off.
Stop the engine. Make sure the vacuum is 0 kPa. Check if the brake fluid pressure is within the allowable values at 150 N and 300 N brake pedal force.
Permissible brake fluid pressure values:
with a pedal force of 150 N:
- 2WD models without ABS - 0.3-1.1 MPa
- other models - 0.1-0.9 MPa
with a pedal force of 300 N:
- 2WD models without ABS - 1.7-2.5 MPa
- 4WD models without ABS - 1.5-2.3 MPa
- models with ABS - 1.3-2.1 MPa
d) Checking the operation of the amplifier. Start the engine. Create a vacuum of 500 mm. rt. Art. Check the pressure at different brake pedal pressures (see table "Permissible brake fluid pressures").