For petrol models, the low pressure required for this is taken from the intake manifold.
On vehicles with diesel engines, low pressure is generated by a vacuum pump mounted on the engine.
Checking the performance of the vacuum brake booster is necessary in cases where the driver needs to apply too much force on the brake pedal to ensure the desired braking effect.
1. Squeeze out the brake pedal with force down to the stop at least five times with the engine off, then start the engine with the brake pedal depressed. Now the pedal under the foot should be noticeably moved down.
2. Disconnect the low pressure hose 2 from the brake booster 1 and start the engine (see illustration).
14.2 Vacuum brake booster
1 - vacuum brake booster
2 - low pressure supply hose
3 - brake pipelines
4 - master brake cylinder
5 - expansion tank with brake fluid
6 - brake booster sensor
Place your finger on the end of the hose to check for low pressure. If there is no vacuum, then check the condition of the vacuum hose and make sure it is not damaged. If necessary, install a new hose and secure it with clamps.
If low pressure is supplied, then measure it, and if necessary, replace the vacuum booster itself in the workshop.