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Check the brake servo using devices
After installing the brake servo, you follow these steps:
- Top up the brake fluid and bleed the air;
- Check all the connections of the hydraulic brake system for leaks;
- Check and, if necessary, adjust the operation of the brake pedal;
- Check the operation of the braking system. Step 1 | PERFORMANCE ORDER | | 1. With the engine off, repeatedly press the brake pedal. |  | 2. With the brake pedal pressed start up the engine. | | 3. If the brake pedal is moved down immediately after the engine starts, it indicates normal operation of the vacuum brake booster. |
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Step 2 | PERFORMANCE ORDER | | 1. Start up the engine. | | 2. After 1-2 minutes, stop the engine. | | 3. Press the brake pedal with ordinary effort. | | 4. If the first pedal stroke - a long and second course, shorter than the first move, it indicates normal operation of the vacuum brake booster. |  | 5. Otherwise, check up the unilateral vacuum valve or a vacuum hose for damage and check the reliability of their fastenings. |
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Step 3 | PERFORMANCE ORDER | | 1. Start up the engine. | | 2. Press the brake pedal with ordinary effort. | | 3. Stop the engine. | | 4. Slowly depress the brake pedal and hold it for 30 seconds. | | 5. If the pedal height does not change, the vacuum brake booster is working properly. |  | 6. Otherwise check up the unilateral vacuum valve or a vacuum hose for damage and check the reliability of their fastenings.
If the problem still persists, perform a detailed inspection using a pressure gauge and a vacuum gauge. |
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CHECK brake servo using devices
A warning  For testing use the available vacuum gauge and a device for measuring the force applied to the brake pedal.
| Connect the gauge A and a device for measuring force in applied to the brake pedal. After removing the air tested below. |
Checking vacuum retention
| PERFORMANCE ORDER | | 1. Start up the engine. | | 2. Turn off the engine if the gauge shows a vacuum of 66.7 kPa (500 mm Hg). | | 3. Observe the gauge readings for 15 seconds. If the gauge shows a vacuum 63,3-66,7 kPa (475-500 mm Hg), then booster is operating normally. |
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Check vacuum under load | PERFORMANCE ORDER | | 1. Start up the engine. | | 2. Press the brake pedal with a force of 196 N (20 kg). | | 3. While pressing the brake pedal, turn off the engine if the gauge shows a vacuum of 66.7 kPa (500 mm Hg). | | 4. Observe the gauge readings for 15 seconds. If the gauge shows a vacuum 63,3-66,7 kPa (475-500 mm Hg), then booster is operating normally. |
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Checking the hydraulic pressure
| PERFORMANCE ORDER |  | 1. If the engine is off (vacuum 0 kPa) water pressure is within the required limits, then booster is operating normally.
The force applied to the brake pedal, H | Fluid pressure, kPa | 196 | 12.171 |
|  | 2. Start up the engine. When the vacuum reaches 66.7 kPa (500 mm Hg), depress the brake pedal and check the water pressure. If the hydraulic pressure is within the required limits, then booster is operating normally.
The force applied to the brake pedal, H | Fluid pressure, kPa | 196 | 82.165 |
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