Examination
1. The performance of the vacuum pump of the brake system can be checked using a vacuum gauge.
2. Disconnect the vacuum tube from the pump and connect the device to the pump fitting using a hose of the appropriate length.
3. Start the engine and let it idle. Then measure the vacuum generated by the pump. The minimum should be 500 mm. rt. Art. If the pressure value is worse than specified, the pump is faulty. However, before replacing the pump, consult your Mercedes-Benz dealer.
Removing
4. Remove the radiator fan as described in Chapter 3.
5. Remove the accessory drive belt as described in Chapter 1.
6. Loosen the union nut and disconnect the vacuum hose from the top of the pump, which is mounted on the front of the cylinder heads.
7. Loosen and remove the pump mounting bolts and remove it from the cylinder head. Remove the pump gasket and discard it.
Installation
8. Installation is carried out in the reverse order. Use a new gasket and make sure the pump drive flange is properly aligned.