Examination
1. The performance of the brake system vacuum pump can be checked using a vacuum gauge.
2. Disconnect the vacuum tube from the pump and connect the device to the pump nipple using a hose of appropriate length.
3. Start the engine and let it idle. Then measure the vacuum created by the pump. It should be at least 500 mm Hg. If the pressure value is worse than the specified value, the pump is faulty. However, before replacing the pump, consult your Mercedes-Benz dealer.
Removal
4. Remove the radiator fan as described in Chapter 3.
5. Remove the accessory drive belt as described in Chapter 1.
6. Loosen the nipple nut and disconnect the vacuum hose from the top of the pump, which is attached to 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 reverse order. Use a new gasket and make sure that the pump drive flange is correctly aligned.