Checking Vacuum Pump

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Information

This check mainly involves examining the secondary load connection due to problems. The main connection (brake booster) is not checked. Defects in the main connection would be apparent immediately due to increasing pedal forces during braking (similar to a defective brake booster).

Expose the secondary load connection of the vacuum pump -5- . Different preliminary work is required, depending on the model and equipment variant.

Fig 1: Identifying Vacuum Pump With Connections
Courtesy of PORSCHE CARS NORTH AMERICA, INC.
1. Vacuum pump
2. Screw, M6 x 25
3. Sealing ring
4. Sealing ring
5. Secondary load connection
Connect vacuum gauge tester 9160/1 to the secondary load connection.
Set vacuum gauge tester 9160/1 to vacuum (lever in open position).
Start engine and run it at idle speed with slightly changing revs.
The vacuum pump must create a vacuum of at least 500 mbar or 0.5 bar.
If the vacuum is not maintained, i.e. the pointer moves towards 0, the vacuum pump is defective. Replace the vacuum pump. For details, see → 477619 REMOVING AND INSTALLING VACUUM PUMP
This defect can cause engine oil to get into the vacuum system. In this case, the lines and switching valves must be checked visually and replaced if necessary or cleaned with solvent naphtha.