2004 CHRYSLER VOYAGER brake fluid

(3) Install the disc brake caliper over the brake
shoes on the brake caliper adapter. (4) Align the caliper guide pin bolt holes with the
guide pins. Install the caliper guide pin bolts and
tighten them to a torque of 35 N´m (26 ft. lbs.) (Fig.
42). (5) Install the tire and wheel assembly. Tighten
the wheel mounting nuts to a torque of 135 N´m (100
ft. lbs.). (6) Lower the vehicle.
(7) Pump the brake pedal several times before
moving the vehicle to set the shoes to the brake
rotor.
DRUM
REMOVAL
(1) Raise the vehicle. (Refer to LUBRICATION &
MAINTENANCE/HOISTING - STANDARD PROCE-
DURE). (2) Remove the tire and wheel assembly from the
vehicle (3) Remove the rear brake shoe adjusting hole
cover plug. (4) Insert a thin screwdriver into brake adjusting
hole and hold adjusting lever away from notches of
adjusting screw star wheel. (5) Insert another thin screwdriver into brake
adjusting hole and engage notches of brake adjusting
screw star wheel. Release brake adjustment by pry-
ing upward with adjusting tool. (6) Remove rear brake drum from rear hub/bear-
ing assembly. NOTE: It may be necessary to insert M8 X 1.25 MM
bolts into the two removal holes on the drum to
force the drum off the hub.
INSTALLATION
(1) Adjust brake shoe assemblies so as not to inter-
fere with brake drum installation. (2) Install the rear brake drums on the hubs.
(3)
Adjust drum brake shoes as necessary per proce-
dure found in the Adjustment section of this service
manual group (Refer t o 5 - BRAKES/HYDRAULIC/
MECHANICAL/DRUM - ADJUSTMENTS).
(4) Install wheel and tire assembly.
(5) Tighten the wheel mounting stud nuts in
proper sequence until all nuts are torqued to half
specification. Then repeat the tightening sequence to
the full specified torque of 135 N´m (100 ft. lbs.). (6) Lower the vehicle.
FLUID
DIAGNOSIS AND TESTING - BRAKE FLUID
CONTAMINATION
Indications of fluid contamination are swollen or
deteriorated rubber parts. Swollen rubber parts indicate the presence of
petroleum in the brake fluid. To test for contamination, put a small amount of
drained brake fluid in clear glass jar. If fluid sepa-
rates into layers, there is mineral oil or other fluid
contamination of the brake fluid. If brake fluid is contaminated, drain and thor-
oughly flush system. Replace master cylinder, propor-
tioning valve, caliper seals, wheel cylinder seals,
Antilock Brake hydraulic unit and all hydraulic fluid
hoses.
STANDARD PROCEDURE - BRAKE FLUID
LEVEL CHECKING
Check master cylinder reservoir fluid level a mini-
mum of twice annually. Fluid reservoirs are marked with the words FULL
and ADD to indicate proper brake fluid fill level of
the master cylinder. If necessary, add brake fluid to bring the level to
the bottom of the FULL mark on the side of the mas-
ter cylinder fluid reservoir. Use only Mopar tbrake fluid or equivalent from a
sealed container. Brake fluid must conform to DOT 3
specifications (DOT 4 or DOT 4+ are acceptable). DO NOT use brake fluid with a lower boiling
point, as brake failure could result during prolonged
hard braking.
Fig. 43 Guide Pins And Boots
1 - PINS
2 - BOOTS
RS BRAKES5s-31
DISC BRAKE CALIPER GUIDE PINS (Continued)

Use only brake fluid that was stored in a tightly-
sealed container. DO NOT use petroleum-based fluid because seal
damage will result. Petroleum based fluids would be
items such as engine oil, transmission fluid, power
steering fluid etc.
SPECIFICATIONS
BRAKE FLUID
The brake fluid used in this vehicle must conform
to DOT 3 specifications (DOT 4 and DOT 4+ are
acceptable) and SAE J1703 standards. No other type
of brake fluid is recommended or approved for usage
in the vehicle brake system. Use only Mopar tBrake
Fluid or equivalent from a tightly sealed container.
CAUTION: Never use reclaimed brake fluid or fluid
from an container which has been left open. An
open container of brake fluid will absorb moisture
from the air and contaminate the fluid.
CAUTION: Never use any type of a petroleum-based
fluid in the brake hydraulic system. Use of such
type fluids will result in seal damage of the vehicle
brake hydraulic system causing a failure of the
vehicle brake system. Petroleum based fluids would
be items such as engine oil, transmission fluid,
power steering fluid, etc.
JUNCTION BLOCK
DESCRIPTION - NON-ABS JUNCTION BLOCK
A junction block is used on vehicles that are not
equipped with antilock brakes (ABS). The junction
block mounts in the same location as the integrated
control unit (ICU) does on vehicles equipped with
ABS. This allows for use of the same brake tube con-
figuration on all vehicles. The junction block is located
on the driver's side of the front suspension cradle/
crossmember below the master cylinder (Fig. 44).
It has six threaded ports to which the brake tubes
connect. Two are for the primary and secondary
brake tubes coming from the master cylinder. The
remaining four are for the chassis brake tubes going
to each brake assembly.
OPERATION - NON-ABS JUNCTION BLOCK
The junction block distributes the brake fluid com-
ing from the master cylinder primary and secondary
ports to the four chassis brake tubes leading to the
brakes at each wheel. Since the junction block
mounts in the same location as the ABS integrated control unit (ICU), it allows for the common use of
brake tubes going to the brakes whether the vehicle
is equipped with or without ABS.
NOTE: Although the brake tubes coming from the
master cylinder to the junction block or ABS ICU
may appear to be the same, they are not. They are
unique to each brake system application.
REMOVAL - NON-ABS JUNCTION BLOCK
(1) Using a brake pedal depressor, move and lock
the brake pedal to a position past its first 1 inch of
travel. This will prevent brake fluid from draining
out of the master cylinder when the brake tubes are
removed from the junction block. (2) Disconnect the battery negative cable.
(3) If the vehicle is equipped with speed control,
perform the following: (a) Disconnect the battery positive cable.
(b) Remove the battery (Refer t o 8 - ELECTRI-
CAL/BATTERY SYSTEM/BATTERY - REMOVAL). (c) Disconnect the vacuum hose connector at the
tank built into the battery tray. (d) Remove the screw securing the coolant filler
neck to the battery tray. (e) Remove the battery tray (Refer t o 8 - ELEC-
TRICAL/BATTERY SYSTEM/TRAY - REMOVAL). (f) Remove the fasteners and move the speed
control servo off to the side, out of the way.
CAUTION: Before removing the brake tubes from
the junction block, the junction block and the brake
tubes must be thoroughly cleaned. This is required
to prevent contamination from entering the brake
hydraulic system. (4) Remove the four chassis brake tubes from the
top of the junction block (Fig. 44). (5) Remove the primary and secondary brake
tubes from the top of the junction block. (6) Remove the bolts attaching the junction block
mounting bracket to the front suspension crossmem-
ber (Fig. 44), then remove the junction block.
INSTALLATION - NON-ABS JUNCTION BLOCK
(1) Install the junction block and mounting bracket
on the front suspension crossmember (Fig. 44).
Install the mounting bolts and tighten to a torque of
28 N´m (250 in. lbs.). (2) Install the primary and secondary brake tubes
from the master cylinder in their ports. Tighten tube
nuts to a torque of 17 N´m (145 in. lbs.). Take care
not to twist tubes when tightening tube nuts.
They must be properly positioned to allow free
movement with rubber isolated suspension
crossmember.
5s - 32 BRAKESRS
FLUID (Continued)

CAUTION: When replacing a master cylinder, be
sure to use the correct master cylinder for the type
of brake system the vehicle is equipped with.The body of the master cylinder is an anodized alu-
minum casting. It has a machined bore to accept the
master cylinder pistons and threaded ports with
seats for the hydraulic brake line connections. The brake fluid reservoir is mounted on the top of
the master cylinder. It is made of a see-through
polypropylene type plastic for easy fluid level view-
ing. A brake fluid level switch is attached to the
brake fluid reservoir. The master cylinder is not a repairable component
and must be replaced if diagnosed to be functioning
improperly. The brake fluid reservoir and brake fluid
level switch can be replaced separately.
CAUTION: Do not hone the bore of the cylinder as
this will remove the anodized surface from the bore.
DESCRIPTION - RHD
The master cylinder used on right hand drive
(RHD) vehicles functions similarly to that used on
left hand drive (LHD) vehicles. The RHD master cyl-
inder, as well as the RHD power brake booster, is
located in the same area, but lower in the engine
compartment than LHD models (Fig. 46). For that
reason an extension manifold is placed between the
fluid reservoir and master cylinder housing allowing
the fluid reservoir to be positioned in the same loca-
tion as on LHD models.
OPERATION
When the brake pedal is depressed, the master cyl-
inder primary and secondary pistons apply brake
pressure through the chassis tubes to the brakes at
each tire and wheel assembly. The master cylinder primary outlet port supplies
hydraulic pressure to the right front and left rear
brakes. The secondary outlet port supplies hydraulic
pressure to the left front and right rear brakes.
STANDARD PROCEDURE - MASTER CYLINDER
BLEEDING
CAUTION: When clamping master cylinder in vise,
only clamp master cylinder by its mounting flange.
Do not clamp master cylinder piston rod, reservoir,
seal or body.
(1) Clamp master cylinder in a vise.
NOTE: Use correct bleeder tubes when bleeding
master cylinder. Master cylinder outlet ports vary in
size and type depending on whether master cylin-
der is for a vehicle equipped with traction control or
not. Traction control equipped master cylinders
require the additional use of ISO style flare adapt-
ers supplied in Special Tool Package 8822 to be
used in conjunction with Bleeder Tubes, Special
Tool Package 8358. (2) Attach special tools for bleeding master cylin-
der in the following fashion: (a)For non-traction control equipped mas-
ter cylinders , thread a Bleeder Tube, Special Tool
8358±1, into each outlet port. Tighten each tube to
17 N´m (145 in. lbs.) torque. Flex bleeder tubes and
place open ends into mouth of fluid reservoir as far
down as possible (Fig. 47). (b) For traction control equipped master
cylinders , thread one Adapter, Special Tool
8822±2, in each outlet port. Tighten Adapters to 17
N´m (145 in. lbs.) torque. Next, thread a Bleeder
Tube, Special Tool 8358±1, into each Adapter.
Tighten each tube to 17 N´m (145 in. lbs.) torque.
Flex bleeder tubes and place open ends into mouth
of fluid reservoir as far down as possible (Fig. 47).
NOTE: Make sure open ends of bleeder tubes stay
below surface of brake fluid once reservoir is filled
to proper level. (3) Fill brake fluid reservoir with Mopar tbrake
fluid or equivalent conforming to DOT 3 (DOT 4 and
DOT 4+ are acceptable) specifications. Make sure
fluid level is above tips of bleeder tubes in reservoir
to ensure no air is ingested during bleeding.
Fig. 46 RHD MASTER CYLINDER AND POWER BRAKE BOOSTER
1 - POWER BRAKE BOOSTER
2 - BRAKE FLUID LEVEL SWITCH
3 - FLUID RESERVOIR
4 - MASTER CYLINDER
5s - 34 BRAKESRS
MASTER CYLINDER (Continued)

(4) Using a wooden dowel as a pushrod (Fig. 47),
slowly depress master cylinder pistons, then release
pressure, allowing pistons to return to released posi-
tion. Repeat several times until all air bubbles are
expelled. Make sure fluid level stays above tips of
bleeder tubes in reservoir while bleeding. (5) Remove bleeder tubes from master cylinder
outlet ports, then plug outlet ports and install fill cap
on reservoir. (6) Remove master cylinder from vise.
(7) Install master cylinder on vehicle. (Refer to 5 -
BRAKES - BASE/HYDRAULIC/MECHANICAL/MAS-
TER CYLINDER - INSTALLATION)
REMOVAL
REMOVAL - LHD
CAUTION: Vacuum in the power brake booster must
be pumped down (removed) before removing mas-
ter cylinder from power brake booster. This is nec-
essary to prevent the power brake booster from
sucking in any contamination as the master cylin-
der is removed. This can be done simply by pump-
ing the brake pedal, with the vehicle's engine not
running, until a firm feeling brake pedal is achieved.
(1) With engine not running, pump brake pedal
until a firm pedal is achieved (4-5 strokes). (2) Disconnect negative battery terminal. (3) Disconnect positive battery terminal.
(4) Remove battery shield.
(5) Remove nut and clamp securing battery to tray,
remove battery. (6) Thoroughly clean all surfaces of the brake fluid
reservoir and master cylinder. Use only solvent such
as Mopar tBrake Parts Cleaner or equivalent.
(7) Remove wiring harness connector from brake
fluid level switch in master cylinder brake fluid res-
ervoir (Fig. 48).
(8) Disconnect primary and secondary brake tubes
from master cylinder housing (Fig. 48). Install seal-
ing plugs in the now open brake tube outlet ports.
CAUTION: Before removing the master cylinder
from the power brake vacuum booster, the master
cylinder and vacuum booster must be thoroughly
cleaned. This must be done to prevent dirt particles
from falling into the power brake vacuum booster.
(9) Clean area where master cylinder assembly
attaches to power brake booster. Use only a solvent
such as Mopar tBrake Parts Cleaner or equivalent.
(10) Remove two nuts attaching master cylinder to
power brake booster (Fig. 49). (11) Slide master cylinder straight out of power
brake booster.
CAUTION: A seal on the rear of the master cylinder
is used to create the seal for holding vacuum in the
power brake vacuum booster. The vacuum seal on
the master cylinder MUST be replaced whenever the
master cylinder is removed from the power brake
vacuum booster.
Fig. 47 Master Cylinder Set Up For Bleeding
1 - BLEEDER TUBES 8358
2 - WOODEN DOWEL
3 - ADAPTER 8822-2 (USE ONLY ON TRACTION CONTROL
EQUIPPED MASTER CYLINDERS)
4 - ADAPTER 8822-2 (USE ONLY ON TRACTION CONTROL
EQUIPPED MASTER CYLINDERS)
Fig. 48 MASTER CYLINDER AND BOOSTER
1 - POWER BRAKE BOOSTER
2 - BOOSTER IDENTIFICATION LABEL
3 - FLUID LEVEL SWITCH CONNECTOR
4 - PRIMARY BRAKE TUBE NUT
5 - SECONDARY BRAKE TUBE NUT
6 - MASTER CYLINDER
RS BRAKES5s-35
MASTER CYLINDER (Continued)

(12) Remove vacuum seal located on the mounting
flange of the master cylinder. The vacuum seal is
removed from master cylinder by carefullypulling it
off the rear of master cylinder. Do not attempt to
pry the seal off the master cylinder by inserting
a sharp tool between seal and master cylinder
casting.
REMOVAL - RHD
CAUTION: Vacuum in the power brake booster must
be pumped down (removed) before removing mas-
ter cylinder from power brake booster. This is nec-
essary to prevent the power brake booster from
sucking in any contamination as the master cylin-
der is removed. This can be done simply by pump-
ing the brake pedal, with the vehicle's engine not
running, until a firm feeling brake pedal is achieved.
(1) With engine not running, pump brake pedal
until a firm pedal is achieved (4 or 5 strokes). (2) Disconnect negative battery terminal.
(3) Disconnect positive battery terminal.
(4) Remove battery shield.
(5) Remove nut and clamp securing battery to tray,
remove battery. (6) Thoroughly clean all surfaces of the brake fluid
reservoir and master cylinder. Use only solvent such
as Mopar tBrake Parts Cleaner or equivalent.
(7) Remove wiring harness connector from brake
fluid level switch in master cylinder brake fluid res-
ervoir (Fig. 46). (8) Disconnect primary and secondary brake tubes
from master cylinder housing (Fig. 50). Install seal-
ing plugs in the now open brake tube outlet ports. CAUTION: Before removing the master cylinder
from the power brake vacuum booster, the master
cylinder and vacuum booster must be thoroughly
cleaned. This must be done to prevent dirt particles
from falling into the power brake vacuum booster.
(9) Clean area where master cylinder assembly
attaches to power brake booster. Use only a solvent
such as Mopar tBrake Parts Cleaner or equivalent.
(10) Remove two nuts attaching master cylinder to
power brake booster (Fig. 50). (11) Slide master cylinder straight out of power
brake booster.
CAUTION: A seal on the rear of the master cylinder
is used to create the seal for holding vacuum in the
power brake vacuum booster. The vacuum seal on
the master cylinder MUST be replaced whenever the
master cylinder is removed from the power brake
vacuum booster.
(12) Remove vacuum seal located on the mounting
flange of the master cylinder. The vacuum seal is
removed from master cylinder by carefullypulling it
off the rear of master cylinder. Do not attempt to
pry the seal off the master cylinder by inserting
a sharp tool between seal and master cylinder
casting.
DISASSEMBLY - MASTER CYLINDER (FLUID
RESERVOIR)
(1) Clean master cylinder housing and brake fluid
reservoir. Use only a solvent such as Mopar Brake
Parts Cleaner or an equivalent.
Fig. 49 MASTER CYLINDER MOUNTING
1 - MASTER CYLINDER MOUNTING NUTS
2 - MASTER CYLINDER
3 - SECONDARY TUBE NUT AT ICU
4 - PRIMARY TUBE NUT AT ICU
Fig. 50 RHD MASTER CYLINDER MOUNTING
1 - PRIMARY BRAKE TUBE NUT
2 - SECONDARY BRAKE TUBE NUT
3 - MASTER CYLINDER MOUNTING NUTS
5s - 36 BRAKESRS
MASTER CYLINDER (Continued)

(2) Remove brake fluid reservoir cap. Using a
syringe or equivalent type tool empty as much brake
fluid as possible from the reservoir.
CAUTION: When removing fluid reservoir from the
master cylinder, do not pry off using any type of
tool. This can damage the fluid reservoir or master
cylinder housing.
(3) Remove the master cylinder assembly from the
power brake vacuum booster. (Refer t o 5 - BRAKES -
BASE/HYDRAULIC/MECHANICAL/MASTER CYL-
INDER - REMOVAL). (4) Mount the master cylinder in a vise using the
master cylinder mounting flange. (5) Using correct size pin punch, remove the two
retaining pins between the fluid reservoir and master
cylinder housing (Fig. 51).
(6) Rock the brake fluid reservoir from side to side
while pulling up to remove it from the seal grommets
in master cylinder housing. (7) Remove the two master cylinder housing to
brake fluid reservoir seal grommets (Fig. 52).
ASSEMBLY - MASTER CYLINDER (FLUID
RESERVOIR)
(1) Install new master cylinder housing to brake
fluid reservoir sealing grommets in master cylinder
housing (Fig. 52). (2) Lubricate reservoir mounting area with fresh
clean brake fluid. Place reservoir in position over
sealing grommets. Seat reservoir into sealing grom-
mets using a rocking motion while firmly pressing
down on fluid reservoir. (3) Be sure fluid reservoir is positioned properly on
master cylinder. Bottom of fluid reservoir is to be touching the top of both sealing grommets
when properly installed on master cylinder
housing.
(4) Install the two fluid reservoir to master cylin-
der retaining pins (Fig. 51). (5) Install the master cylinder assembly on the
power brake booster. (Refer t o 5 - BRAKES/HY-
DRAULIC/MECHANICAL/MASTER CYLINDER -
INSTALLATION) (6) Fill fluid reservoir to its proper level as indi-
cated on the side of the fluid reservoir.
INSTALLATION
INSTALLATION - LHD
CAUTION: Different types of master cylinders are
used on this vehicle depending on brake options. If
a new master cylinder is being installed, be sure it
is the correct master cylinder for the type of brake
system the vehicle is equipped with.
CAUTION: When replacing the master cylinder on a
vehicle, a NEW vacuum seal MUST be installed on
the master cylinder.
(1) Install a NEW vacuum seal on master cylinder
making sure seal fits squarely in groove of master
cylinder casting. (2) Position master cylinder on studs of power
brake booster, aligning booster push rod with master
cylinder piston. (3) Install the two master cylinder mounting nuts
(Fig. 49). Tighten both mounting nuts to a torque of
25 N´m (225 in. lbs.).
Fig. 51 Fluid Reservoir Retaining Pins (Typical)
1 - FLUID RESERVOIR
2 - RETAINING PINS
3 - MASTER CYLINDER
Fig. 52 Master Cylinder To Fluid Reservoir Seal Grommets
1 - SEAL GROMMETS
2 - MASTER CYLINDER
RS BRAKES5s-37
MASTER CYLINDER (Continued)

CAUTION: When tightening the primary and sec-
ondary brake tube nuts at master cylinder, be sure
brake tubes do not contact any other components
within the vehicle and that there is slack in the flex-
ible sections of the tubes. This is required due to
the movement between the ABS ICU and the master
cylinder while the vehicle is in motion.(4) Connect primary and secondary brake tubes to
master cylinder primary and secondary ports (Fig.
48). Brake tubes must be held securely when tight-
ened to control orientation of flex section. Tighten
tube nuts to a torque of 17 N´m (145 in. lbs.). (5) Install wiring harness connector to brake fluid
level switch mounted in brake fluid reservoir (Fig.
48). (6) Install battery, clamp and nut.
(7) Install battery shield.
(8) Connect positive battery terminal.
(9) Connect negative battery terminal.
(10) Fill master cylinder with clean, fresh Mopar t
Brake Fluid or equivalent. (11) Road test vehicle to ensure proper operation of
brakes.
INSTALLATION - RHD
CAUTION: Different types of master cylinders are
used on this vehicle depending on brake options. If
a new master cylinder is being installed, be sure it
is the correct master cylinder for the type of brake
system the vehicle is equipped with.
CAUTION: When replacing the master cylinder on a
vehicle, a NEW vacuum seal MUST be installed on
the master cylinder.
(1) Install a NEW vacuum seal on master cylinder
making sure seal fits squarely in groove of master
cylinder casting. (2) Position master cylinder on studs of power
brake booster, aligning booster push rod with master
cylinder piston. (3) Install the two master cylinder mounting nuts
(Fig. 50). Tighten both mounting nuts to a torque of
25 N´m (225 in. lbs.).
CAUTION: When tightening the primary and sec-
ondary brake tube nuts at master cylinder, be sure
brake tubes do not contact any other components
within the vehicle and that there is slack in the flex-
ible sections of the tubes. This is required due to
the movement between the ABS ICU and the master
cylinder while the vehicle is in motion. (4) Connect primary and secondary brake tubes to
master cylinder primary and secondary ports (Fig.
50). Brake tubes must be held securely when tight-
ened to control orientation of flex section. Tighten
tube nuts to a torque of 17 N´m (145 in. lbs.). (5) Install wiring harness connector to brake fluid
level switch mounted in brake fluid reservoir (Fig.
46). (6) Install battery, clamp and nut.
(7) Install battery shield.
(8) Connect positive battery terminal.
(9) Connect negative battery terminal.
(10) Fill master cylinder with clean, fresh Mopar t
Brake Fluid or equivalent. (11) Road test vehicle to ensure proper operation of
brakes.
PEDALS - ADJUSTABLE
REMOVAL
NOTE: Before proceeding, review all Steering Col-
umn and Airbag Warnings and Cautions. (Refer to
19 - STEERING/COLUMN - WARNING)(Refer to 8 -
ELECTRICAL/RESTRAINTS - WARNING)
(1) Move driver's seat to full rearward position.
(2) Disconnect negative battery cable from battery
post and isolate. (3) Remove throttle cable from throttle body lever.
(Refer to 14 - FUEL SYSTEM/FUEL INJECTION/
THROTTLE CONTROL CABLE - REMOVAL) (4) Remove screws securing lower steering column
cover/knee blocker, then remove it (Fig. 53). (5) Disconnect parking brake release link at
release handle. (6) Compress tabs on sides of data link diagnostic
connector and remove it from knee blocker reinforce-
ment plate. (7) Remove screws securing knee blocker reinforce-
ment plate in place, then remove reinforcement plate
(Fig. 53). (8) Remove hood release from lower left reinforce-
ment. (9) Remove screws securing instrument panel
lower left reinforcement in place, then remove rein-
forcement (Fig. 54). (10) Remove brake lamp switch. Discard original
switch; it must not be reused. (Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/BRAKE
LAMP SWITCH - REMOVAL) (11) Remove upper and lower steering column
shrouds. (Refer to 19 - STEERING/COLUMN/
LOWER SHROUD - REMOVAL)
5s - 38 BRAKESRS
MASTER CYLINDER (Continued)

NOTE: The power brake booster assembly is not a
repairable component and must be replaced as a
complete assembly if found to be faulty in any way.
The check valve located on the power brake
booster face is not repairable, but it can be
replaced separately from the power brake booster.The different engine combinations used in this
vehicle require different vacuum hose routings to the
power brake booster. All vacuum hoses must be
routed from the engine to the power brake booster
without kinks or excessively tight bends.
OPERATION
The power brake booster reduces the amount of
force required by the driver to obtain the necessary
hydraulic pressure to stop a vehicle. The power brake booster is vacuum operated. The
vacuum is supplied from the intake manifold on the
engine through a vacuum hose and the power brake
booster check valve (Fig. 64). As the brake pedal is depressed, the power brake
booster's input rod moves forward (Fig. 64). This
opens and closes valves in the power booster allowing
atmospheric pressure to enter on one side of a dia-
phragm. Engine vacuum is always present on the
other side. This difference in pressure forces the out-
put rod of the power brake booster out against the
primary piston of the master cylinder. As the pistons
in the master cylinder move forward this creates the
hydraulic pressure in the brake system.
DIAGNOSIS AND TESTING - POWER BRAKE
BOOSTER
BASIC TEST
(1) With engine off, depress and release the brake
pedal several times to purge all vacuum from the
power brake booster. (2) Depress and hold the pedal with light effort (15
to 25 lbs. pressure), then start the engine. The pedal should fall slightly, then hold. Less effort
should be needed to apply the pedal at this time. If
the pedal fell as indicated, perform the VACUUM
LEAK TEST listed after the BASIC TEST. If the
pedal did not fall, continue on with this BASIC
TEST. (3) Disconnect the vacuum hose on the vacuum
check valve, then place a vacuum gauge in line
between the vacuum hose and the valve. (4) Start the engine.
(5) When the engine is at warm operating temper-
ature, allow it to idle and check the vacuum at the
gauge. If the vacuum supply is 12 inches Hg (40.5 kPa) or
more, the power brake booster is defective and must
be replaced. If the vacuum supply is below 12 inches
Hg, continue on with this BASIC TEST. (6) Shut off the engine.
(7) Connect the vacuum gauge to the vacuum ref-
erence port on the engine intake manifold. (8) Start the engine and observe the vacuum
gauge. If the vacuum is still low, check the engine tune
and repair as necessary. If the vacuum is above 12
inches Hg, the hose or check valve to the booster has
a restriction or leak. Once an adequate vacuum supply is obtained,
repeat the BASIC TEST.
VACUUM LEAK TEST
(1) Disconnect the vacuum hose on the vacuum
check valve, then place a vacuum gauge in line
between the vacuum hose and the valve. (2) Start the engine.
(3) Allow the engine to warm up to normal operat-
ing temperature and engine idle. (4) Using vacuum line pliers, close off the vacuum
supply hose near the booster, but before the vacuum
gauge, then observe the vacuum gauge. If the vacuum drop exceeds 1.0 inch Hg (3.3 kPa)
in one minute, repeat the above steps to confirm the
reading. The vacuum loss should be less than 1.0
inch Hg in one minute time span. If the loss is more
than 1.0 inch Hg, replace the power brake booster. If
it is not, continue on with this test. (5) Remove the pliers from the hose temporarily.
Fig. 65 MASTER CYLINDER AND BOOSTER
1 - POWER BRAKE BOOSTER
2 - BOOSTER IDENTIFICATION LABEL
3 - FLUID LEVEL SWITCH CONNECTOR
4 - PRIMARY BRAKE TUBE NUT
5 - SECONDARY BRAKE TUBE NUT
6 - MASTER CYLINDER
5s - 44 BRAKESRS
POWER BRAKE BOOSTER (Continued)