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Check of serviceability of functioning of the vacuum brake booster
Checks performed without the use of special equipment Step 1 | - When the engine is stopped repeatedly depress the foot brake.
- Depress the pedal and hold it down, start the engine, while serviceable vacuum amplifier the pedal should be slightly "fall" immediately after the launch.
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Step 2 | - In a minute or two will start the engine, then it shut off again.
- Several times depress the foot brake with usual effort - if each time you press the pedal travel will be reduced, therefore, the vacuum amplifier is functioning properly.
- In case of problems, check the condition of the control valve and connecting a vacuum hose, make the necessary corrections, then recheck.
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Step 3 | - Start the engine, depress the brake pedal with a conventional force and hold it down, stop the engine.
- Continue to hold the pedal down for a further about 30 seconds - if the height of the pedal will not change, therefore, the vacuum amplifier is functioning properly.
- In case of problems, check the condition of the control valve and connecting a vacuum hose, make the necessary corrections, then recheck.
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Checks carried out by using measuring devices | - Connect the brake booster meters.
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Leak test with no load | - Start the engine and silencers it as long as the depth of the vacuum in the brake booster reaches the point A = 66.7 kPa (500 mm Hg. V.), - The foot brake is not wring.
- Stop the engine and observe the gauge readings, - the rate of decline in working depth of the vacuum amplifier is not more than 3.3 kPa for 15 seconds. If any signs of leakage should check the status of the check valve, vacuum hose, to assess the quality of the weld the housing, ensure that no damage of the diaphragm and signs of leakage through the plate, seal and poppet valve. If necessary, replace assemblage of the vacuum amplifier.
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Leak test under load | - Start the engine, depress the brake pedal with a force of 20 kgf and hold it, wait for the descent into the depths of the vacuum brake booster to point B = 66.7 kPa (500 mm Hg. Art.).
- Stop the engine and observe the vacuum reading - fall speed vacuum again, must not exceed 3.3 kPa for 15 seconds. In case of need make corresponding regenerative repair, or replace the amplifier.
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Checking the hydraulic pressure | - When the engine is stopped (depth 0 mm Hg vacuum. Art.) Squeezing the brake pedal with a force of 20 kgf should raise the pressure in the hydraulic path to a value of 1177 kPa (12 kgf / cm 2), - the pressure gauge reading.
- Start the engine and wait for the lowering depth of dilution to the value of 66.7 kPa (500 mm Hg. V.), Then read the pressure gauge reading - required value of 6867 kPa (70 kgf / cm 2). Defective, replace the vacuum booster.
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Checking the status of the control valve |  | - Disconnect from the assembly of the brake booster vacuum hose.
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- A check valve is pressed in the direction of the hose and it is installed inside the latter is shown deposited on the surface of the hose arrow.
- Blow into the hose, - the air must pass freely in the direction of the engine, sucking him in the direction of the brake booster should not be possible. A faulty valve must be replaced.
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