Servo brake of Mercedes 190 D

The servo brake of my car doesn't work for me. Can someone help me? The brake pedal is hard. Thank you :(

It is a 190 diesel, because it is normal to look at the vacuum pipes ranging from servofreno to the vacuum pump.

In the servofreno, on one side of the brake pump, there is a rubber, with a plastic piece (which is an anti -background) and a tectalán tube (hard black plastic).

I want you to remove the valve carefully not to break it, to do so give a little fairy to the rubber of the servo and pull with care of the valve back.

Then you start the engine and put your finger in the tube you just removed, if with the engine running notes such as the tube \ "sucks \" means that the vacuum pump is fine, if you observe a whistle, it means that the black tube of Tecalan broke down somewhere and loses you empty. If you do not notice suction or if the suction is very poor, it means that the vacuum pump has been broken or deteriorated by the use.

Then I want you to stop the car with your finger in the tube (you will need help) if you do not lose a vacuum, (if the finger is still stuck by at least a minute) means that the anti -background valve is fine. If you lose emptiness and release your finger it is because the valve is wrong and does not close tightly.

If all this happens as I have told you, the breakdown will then be in the membrane of the Servofrane, which has been drilled and therefore does not help the word servo, means help) to the braking.

Solution, change the servofrane.

All the best.