Subaru Legacy 2004 Service Manual page 3245

• AIR TIGHTNESS CHECK
1) Start the engine and keep it running until a vac-
uum of 66.7 kPa (500 mmHg, 19.69 inHg) = point A
is indicated on vacuum gauge. Do not depress the
brake pedal at this moment.
(1) (2)
(1) Pressure gauge
(2) Vacuum gauge
2) Stop the engine and watch the gauge. If the vac-
uum drop range is less than 3.3 kPa (25 mmHg,
0.98 inHg) within 15 seconds after stopping the en-
gine, 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 shell jointed portion or stud bolt weld-
ed portion
• Damaged diaphragm
• 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 the engine and depress the brake pedal
with pedal force of 196 N (20 kgf, 44 lb). Keep the
engine running until a vacuum of 66.7 kPa (500
mmHg, 19.69 inHg) = point B is indicated on vacu-
um gauge while the pedal is still depressed.
(1) (2)
(1) Pressure gauge
(2) Vacuum gauge
(3) Pedal force gauge
(4) Depressed
Brake Booster
A
BR-00083
B
(3)
(4)
BR-00084
BR-35
2) Stop the 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
the engine, brake booster is functioning properly.
If defective, refer to "AIR TIGHTNESS CHECK".
<Ref. to BR-33, INSPECTION, Brake Booster.>
3) If any fault is found on brake booster, replace the
brake booster with a new one.
• LACK OF BOOSTING ACTION CHECK
Turn OFF the engine, and set the vacuum gauge
reading at "0". Then, check the fluid pressure when
brake pedal is depressed. The pressure must be
greater than the standard value listed.
Brake pedal force N (kgf, lb)
Fluid pressure
2
kPa (kg/cm , psi)
• BOOSTING ACTION CHECK
Set the vacuum gauge reading at 66.7 kPa (500
mmHg, 19.69 inHg) by running engine. Then,
check the fluid pressure when brake pedal is de-
pressed. The pressure must be greater than the
standard value listed.
Brake pedal force N (kgf, lb)
15$
16$ OUTBACK
Fluid pres-
16$
sure
(Except for
2
kPa (kg/cm ,
OUTBACK)
psi)
17$
BRAKE
147 294
(15, 33) (30, 66)
545 1,564
(6, 79) (16, 227)
147 294
(15, 33) (30, 66)
6,003 11,273
(61, 871) (115, 1,635)
5,381 10,982
(55, 780) (112, 1,593)
4,963 10,055
(51, 720) (103, 1,458)