Subaru 2001 IMPREZA Service Manual page 59

BRAKE
2. OPERATION CHECK (WITH GAUGES)
CAUTION:
When checking operation, be sure to securely
apply the hand brake.
• Checking with gauges
Connect gauges as shown in Figure. After bleeding
air from pressure gauges, proceed to each check.
(1) Pressure gauge
(2) Vacuum gauge
(3) Adapter hose
(4) Vacuum hose
(5) Pedal force gauge
• Air tightness check
1) Start engine and keep it running until a vacuum
of 66.7 kPa (500 mmHg, 19.69 inHg) = point A is in-
dicated on vacuum gauge. Do not depress brake
pedal.
(1) Pressure gauge
(2) Vacuum gauge
2) Stop engine and watch the gauge. If the vacuum
drop range is less than 3.3 kPa (25 mmHg, 0.98 in-
Hg) within 15 seconds after stopping engine, brake
booster is functioning properly.
If defective, the cause may be one of those listed
below.
• Check valve malfunction
• Leak from vacuum hose
• Leak from the shell jointed portion or stud bolt
welded portion
• Damaged diaphragm
BRAKE BOOSTER
• Leak from valve body seal and bearing portion
• Leak from plate and seal assembly portion
• Leak from poppet valve assembly portion
• Loaded air tightness check
1) Start engine and depress brake pedal with pedal
force of 196 N (20 kgf, 44 lb). Keep engine running
until a vacuum of 66.7 kPa (500 mmHg, 19.69 in-
Hg) = point B is indicated on vacuum gauge while
the pedal is still depressed.
S4M0467A
2) Stop engine and watch vacuum gauge.
If the vacuum drop range is less than 3.3 kPa (25
mmHg, 0.98 inHg) within 15 seconds after stopping
engine, brake booster is functioning properly.
If defective, refer to "AIR TIGHTNESS CHECK".
<Ref. to BR-57, INSPECTION, Brake Booster.>
S4M0468A
BR-58
(1) Pressure gauge
(2) Vacuum gauge
(3) Pedal force gauge
(4) Depress
S4M0469A