Removal
Location of the connecting nut for fastening the vacuum hose to the brake booster
1. Unscrew the union nut and disconnect the vacuum hose from the brake booster (see picture).
2. Disconnect the other end of the vacuum hose from the intake manifold or vacuum pump and remove the vacuum hose with the one-way valve from the engine compartment.
Examination
1. Check the condition of the vacuum hose and one-way valve for wear and mechanical damage and replace if necessary.
Publication taken from an online resource MERCEDESMAN
2. Check the one-way valve of the brake booster by blowing air in both directions. Air should only pass through the valve on the brake booster side.
Installation
1. Position the vacuum hose with the valve in the engine compartment, then connect it to the intake manifold or vacuum pump. Connect the other end of the hose to the brake booster and secure it with the union nut, tightening it to the required torque.
2. Start the engine and check the vacuum hose connections for leaks.