Dodge dakota 2002 Service Manual page 253

5 - 26 BRAKES - BASE
HYDRO-BOOST BRAKE BOOSTER (Continued)
HISSING
A hissing noise may be noticed when above normal
brake pedal pressure is applied, 40 lbs. or above. The
noise will be more noticeable if the vehicle is not
moving. The noise will increase with the brake pedal
pressure and an increase of system operating temper-
ature.
CLUNK-CHATTER-CLICKING
A clunk-chatter-clicking may be noticed when the
brake pedal is released quickly, after above normal
brake pedal pressure is applied 50-100 lbs..
BOOSTER FUNCTION TEST
With the engine off depress the brake pedal several
times to discharge the accumulator. Then depress the
brake pedal using 40 lbs. of force and start the
engine. The brake pedal should fall and then push
back against your foot. This indicates the booster is
operating properly.
ACCUMULATOR LEAKDOWN
(1) Start the engine, apply the brakes and turn the
steering wheel from lock to lock. This will ensure the
accumulator is charged. Turn off the engine and let
the vehicle sit for one hour. After one hour there
should be at least two power assisted brake applica-
tion with the engine off. If the system does not retain
a charge the booster must be replaced.
(2) With the engine off depress the brake pedal
several times to discharge the accumulator. Grasp
the accumulator and see if it wobbles or turns. If it
does the accumulator has lost a gas charge and the
booster must be replaced.
SEAL LEAKAGE
If the booster leaks from any of the seals the
booster assembly must be replaced (Fig. 48).
CONDITION
Slow Brake Pedal Return
Excessive Brake Pedal
Effort.
HYDRAULIC BOOSTER DIAGNOSIS CHART
POSSIBLE CAUSES
1. Excessive seal friction in booster.
2. Faulty spool valve action.
3. Restriction in booster return hose.
4. Damaged input rod.
1. Internal or external seal leakage.
2. Faulty steering pump.
• INPUT ROD SEAL: Fluid leakage from rear
end of the booster.
• PISTON SEAL: Fluid leakage from vent at
front of booster.
• HOUSING SEAL: Fluid leakage between hous-
ing and housing cover.
• SPOOL VALVE SEAL: Fluid leakage near
spool plug.
• RETURN PORT FITTING SEAL: Fluid leak-
age from port fitting.
Fig. 48 Hydraulic Booster Seals
1 - PUMP
2 - GEAR
3 - INPUT SEAL
4 - HOUSING SEAL
5 - ACCUMULATOR SEAL
6 - PISTON SEAL
7 - SPOOL PLUG SEAL
8 - RETURN
1. Replace booster.
2. Replace booster.
3. Replace hose.
4. Replace booster.
1. Replace booster.
2. Replace pump.
CORRECTION
DR