brake vacuum booster

[aeneasm]

how can I test booster to verify if operating correctly. brake pedal full and hard. does not progress when engine runs,can feel vacuum in house when taken off vac unit. the basic problem is the pedal is hard and unyielding,and stopping power poor. all new brake pads,lines and hoses.

aeneas

[waqas]

Hello Aeneas,

Do the RPMs change when you try to press the pedal? Have you checked if the booster holds a vacuum? (disconnect at the check-valve and apply vacuum). There are many discussions about power brakes: (the search function works quite nicely)

http://index.php?topic=4961,booster,vacuum
http://index.php?topic=2953,booster,vacuum
http://index.php?topic=3057,booster,vacuum
http://index.php?topic=3101,booster,vacuum
http://index.php?topic=4214,booster,vacuum
http://index.php?topic=4860,booster,vacuum
http://index.php?topic=531,booster,vacuum


WAQAS in Austin, Texas

[aeneasm]

have tried as sugested..with engine running ,press brake(keeping pressed) engine speed increases.stop engine and remove hose from vac drum i can hear air being sucked in.again after engine stop,press brake you hear a noise from vac unit,once only.

aeneas

[ted280sl]

Aeneas,
  Check the flex hoses by the brakes. They should not expand when the brake pedal is depressed.
Regards,
Ted 1968 280sl

[al_lieffring]

aeneas

When pressing the brake pedal the vacuuim booster should only cause the idle speed to increase when the pedal is in motion, When the pedal is being held down, the idle should return to the normal (slower) idle speed. If when holding the pedal down the idle ramains at the faster speed, this indicates the booster is leaking vacuuim.

Al

66 230sl
113-042-10-014715
904/396 blue, Ivory Tex
condition: not-as-rusty-as-before-bucket