Brake Boostertest; Functional Test; Leak Test - Honda EP3 Service Manual

Gonventional Brake Components
I
Brake Booster Test
Functional Test
1. With the engine stopped, press the brake pedal
several times to deplete the vacuum reservoir, then
press the pedal hard, and hold itfor 15 seconds. lf
the pedal sinks, either the master cylinder is
bypassing internally, or the brake system (master
c y l i n d e r , l i n e s . m o d u l a t o r , o r c a l i p e r s ) i s l e a k i n g .
2. Start the engine with the brake pedal pressed. lf the
pedal sinks slightly, the vacuum booster is working
properly. lf the pedal height does not vary, the
booster or check valve is faulty.
3. With the engine running, press the brake pedal
l i g h t l y . l f t h e b r a k e p e d a l s i n k s m o r e t h a n 1 O m m
{3/8 in, ) in 3 minutes, the master cylinder is faulty.
A slight change in pedal height when the Ay'C
compressor cycles on and off is normal. (The A,/C
compressor load changes the vacuum available to
the booster.)
Leak Test
1. Press the brake pedal with the engine running, then
stop the engine. lf the pedal height does not vary
while pressed for 30 seconds, the vacuum booster
is OK. lf the pedal rises, the booster is faulty.
2. With the engine stopped, press the brake pedal
several times using normal pressure. When the
pedal is first pressed, it should oe row.
On consecutive applications, the pedal height
s h o u l d g r a d u a l l y r i s e . l f t h e p e d a l p o s i t i o n d o e s n o t
varv, check the booster check valve.
1 9 - 1 8
3. Disconnect the brake booster vacuum hose (check
valve built-in) (A) at the booster side.
5 .
4 . Start the engine, and let it idle. There should be
v a c u u m a v a i l a b l e . l f n o v a c u u m i s a v a i l a b l e , t h e
check valve is not working properly. Repiace the
brake booster vacuum hose and check valve, and
relesI.
Reconnect the brake booster vacuum nose.
Start the engine, and then pinch the brake booster
vacuum hose between the check valve and the
booster,
Turn the ignition switch OFF, and wait 30 seconds,
Press the brake pedal several times using normal
pressu re,
When the pedal is first pressed, it should be low.
On consecutive applications, the pedal height
s h o u l d g r a d u a l l y r i s e .
. lf the pedal position does notvary, replacethe
brake booster.
. lf the pedal position varies, replace the brake
booster vacuum hose/check valve assembly.