Volkswagen Golf Service & Repair Manual: Checking vacuum generation
 Note
| The average air pressure of the earth's atmosphere at sea
level is 1013 mbar and decreases steeply as the altitude
increases (approx. 100 mbar/1,000 m altitude). Local and time
fluctuations also influence vacuum generation. |
| A cold engine, a switched-on air-conditioning system as well
as engine idling have an adverse influence on generation of a
vacuum. |
| – |
Before starting work, check all vacuum hoses for damage
(e.g. cracks or marten bite) and to check that they are
correctly and firmly attached |
| – |
Connect brake servo vacuum gauge -VAS 6721-
→ Chapter. |
| – |
Open cut-off valve -A-. |
|
|
|
| – |
Close cut-off valves -B+C-. |
| – |
Start warm engine (>60°C), press accelerator briefly (engine
speed above 2,000 rpm). |
| – |
Read indicated measured value. |
| Normally (see notes), the vacuum that is generated should be
between 600 and 950 mbar (depending on engine size). |
| If the measured value is not reached even through the
preconditions (see notes) have been met, the vacuum system must
first be checked for leaks. |
| – |
For comparison purposes, generate the vacuum with the manual
vacuum pump -VAS 6213-
→ Chapter. |
| Open cut-off valve -B- to
facilitate removal of hose connections and adapter. |
|
|
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Special tools and workshop equipment
required
Vacuum gauge for brake servo -VAS 6721-
...
Note
The average air pressure of the earth's atmosphere at sea
level is 1013 mbar and decreases steeply as the altitude
increases (approx. 100 mb ...
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Connecting vacuum gauge for brake servo -VAS 6721-
Checking for leaks