Brake Booster Tests - Honda Acura NSX 1991 Service Manual

Brake Booster
Functional Test
1 . With the engine stopped, depress the brake pedal
several times, then depress the pedal hard and hold
that pressure for 15 seconds. If the pedal sinks, the
master cylinder, brake line or a brake caliper is
faulty.
2. Start the engine with the pedal depressed. If the
pedal sinks slightly, the vacuum booster is work-
ing. If the pedal height does not vary, the booster or
check valve is faulty.
Leak Test
1 . Depress the brake pedal with the engine running,
then stop the engine. If the pedal height does not
vary while depressed for 30 seconds, the vacuum
booster is OK. If the pedal rises, the booster is
faulty.
CAUTION: Do not try to disassemble the booster.
Replace the booster assembly with a new one.
2. With the engine stopped, depress the brake pedal
several times using normal pressure. When the
pedal is first depressed, it should be low. On con-
secutive applications, pedal height should gradual-
ly rise. If the pedal position does not vary, check
the booster check valve.
VACUUM
HOSE
19-14
Check Valve Test
1 . Disconnect the brake booster vacuum hose at the
booster.
2. Start the engine and let it idle. There should be
vacuum available. If no vacuum is available, the
check valve is not working correctly.
Replace the check valve and retest.
CHECK VALVE