RE: [alfa] checking brake boosters

["Jeff Greenfield" <alfaguy@xxxxxxxxxxxx>]

One last thought on testing brake boosters ...

If you pull a vacuum on one, and it holds, you should operate the plunger
while it is connected to the vacuum pump and gauge.

It is common for brake boosters to hold vacuum statically, but leak when
operated (although I have never seen this mode of failure on an Alfa, but
have on other cars).

Jeff




     You can put air pressure or vacuum on the booster and see if the
diaphragm leaks.  You need to seal the mount for the master cylinder with
something -
something like a master cylinder, maybe?  Make sure the master cylinder
gasket is good.
    All that will tell is if the diaphragm is torn.  Most of the time that
is
sufficient.  However, I have had boosters pass the pressure test and fail in

use.  Perhaps they had a pin hole leak that I did not detect.  I did not
devise a way to apply pressure / vacuum and hold it to test leak down time.
    Plus you need to visually inspect the booster inside and out and make
sure the mechanism moves freely by pushing it with a Phillips screwdriver.


Ciao,
Russ Neely
Oklahoma City
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