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-. |
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|
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| – |
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 ...
Other materials:
Bleeding hydraulic system following standard procedure
Note
Bleeding the hydraulic system using brake filling and
bleeding equipment -VAS 5234- is described.
A pre-pressure of 2 bar is required for bleeding the ABS
hydraulic unit -N55-.
Specia ...
Securing engine on engine and gearbox support
Special tools and workshop equipment
required
Engine and gearbox support -VAS 6095-
Workshop hoist -VAS 6100-
...
Instructions for checking
The following instructions are intended to help you find the
causes of problems effectively and objectively in the event of
complaints about the brake servo or in the event of a so-called
»hard brake pedal«.
This check relates to the fo ...
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Connecting vacuum gauge for brake servo -VAS 6721-
Checking for leaks