Volkswagen Passat 2011 Workshop Manual page 129

– Close cut-off valves -B+C-.
– Start warm engine (>60° C), press accelerator briefly (engine
speed greater than 2000/min).
Normally (see notes), the vacuum that is generated should be
between 600 and 950 mbar (depending on engine size).
– Open cut-off valve -C- to evacuate brake servo.
– Switch off engine.
– Read and make a note of measured value shown.
A vacuum decrease of 400 mbar in 12 hours is permissible.
If the vacuum decrease is greater, check for leaks in the vicinity
of...
1 - Brake servo
or
2 - non-return valve, vacuum hoses with connectors or vacuum
pump/intake pipe
.
If there are large leaks, the vacuum decreases steeply within a
few seconds.
Vacuum check in vicinity of brake servo:
– After generation of vacuum, close cut-off valve -A- in order to
check brake servo vacuum system.
Vacuum check in vicinity of non-return valve, vacuum hoses with
connectors and vacuum pump/intake pipe:
– After generation of a vacuum, close cut-off valve -C- in order
to check vacuum system from brake servo vacuum gauge -
VAS 6721- to intake pipe or to vacuum pump.
Open cut-off valve -B- to facilitate removal of hose connections
and adapter.
Passat 2011 ➤ , Passat Variant 2011 ➤
Brake systems - Edition 02.2014
125
4. Vacuum system