Porsche 928 - WORKSHOP MANUAL 1977 Workshop Manual page 249

a
928 Brakes/HydrauIic,ReguIator,Booster
47
3. Switch on bleeder. Move selection control
lever to filling and bleeding position.
4. Open each bleeder valve until escaping
brake fluid is without air bubbles.
Note
First bleed the clutch, if the brake master
cylinder or brake fluid tank had been
removed.
The stepped brake master cylinder (since
1984 models) has a bleeder valve for the
intermediate piston brake circuit (rear axle
brake circuit), see point 6.
6. Operate the brake pedal firmly several
times during bleeding procedures and with
the bleeder valves open, in order to remove
all air bubbles in the brake master
cylinder.
If there is a bleeder valve on the master
cylinder, begin bleeding of brakes on this
valve.
Note
There is no difference in bleeding procedures
for cars with ABS.
7. It is recommended to perform a low
Pressure leak test after finishing the bleed-
ing/brake fluid change procedures. This, of
course, requires that the bleeding adapters
and filling hose are connected 100 % tight.
All bleeder valves of the system must be
closed. Keep the selection control lever at
"filling and bleeding"and read pressure on
the operating pressure gauge.
5. Use a bottle to catch the escaping brake
fluid for accurate inspection regarding
cleanliness, air bubbles and determination
of brake fluid consumption.
Printed in Germany -
VI I I, 1984 Bleeding Brakes/Replacing Brake Fluid
47 - 23