Brake Bleeding - Craftsman 20930 Manual Del Operador

Many brake systems today feature Anti-Lock
functions and electronic controls. Many of these
systems use a high pressure electric pump to keep
the system pressurized. When bleeding or servicing,
these systems require special procedures and
cautions.
• ALWAYS observe the following precautions when
servicing Anti-Lock brake system:
• ALWAYS wear safety goggles when servicing high
pressure brake systems.
• ALWAYS depressurize the ABS system prior to
adding fluid or attempting service or repair.
• Unless instructed to by the manufacturer's
procedure, NEVER open a bleeder valve or
loosen a hydraulic line while the ABS system
is pressurized.
• ONLY use recommended brake fluids. DO NOT use
silicone brake fluid in ABS equipped vehicles.
• Always refer to an appropriate repair manual for
additional information on Anti-Lock brake systems.
DEPRESSURIZING ANTI-LOCK
BRAKE SYSTEMS
Always refer to the vehicle owner's manual or
appropriate service manual for additional
information on depressurizing procedure.
The procedure will work on most Anti-Lock brake
systems. Ensure ignition switch is in the OFF
position or disconnect the negative battery cable.
Pump the brake pedal 25 to 40 times. A noticeable
change is felt. Continue to pump the pedal a few
additional times. This should eliminate most system
pressure. Open fluid reservoir or brake lines
carefully. Top off reservoir fluid and reconnect
battery cable when finished.
BLEEDING ANTI-LOCK BRAKE SYSTEMS
Always refer to the vehicle owner's manual or
appropriate service manual for manufacturer's
brake bleeding procedure. The front brakes on
most Anti-Lock brake systems may be bled in the
conventional manner. Most hydraulic pump/pressure

BRAKE BLEEDING

accumulator units are fitted with a bleeder valve
which must be bled when the system has lost fluid or
is being replaced. Some vehicles require that the sys-
tem be pressurized when the rear brakes are bled.
Some automotive manufacturers use bleeding
procedures which require specialized equipment.
BRAKE LINE BLEEDING
Most low and soft pedal problems are caused by air
in the hydraulic lines, which requires bleeding of the
hydraulic system. By using the pump with brake
bleeding accessories, the system can be bled easily.
Follow a wheel-to-wheel sequence beginning with the
wheel closest to the master cylinder.
The kit provides a simple, clean, and quick method
for bleeding the fluid lines in the automotive brake
system. The creation of a vacuum in the reservoir
jar causes fluid to be drawn into the reservoir jar.
It should be noted that a tiny stream of bubbles
may be noticed in the hose after all of the air is bled
from the lines. This is caused by air seeping around
the threads of the loosened bleeder fitting and
being drawn back through the fitting by the suction
of the pump. Once the air is removed from within
the system, these tiny bubbles will in no way
jeopardize the bleeding operation, since they are
present only at the fitting and do not enter the
system. If you wish, you can put grease or Teflon
tape around the threads of the fitting to eliminate
most of the bubbles. The correct bleeding procedure
follows:
1) Always make certain that the master cylinder
reservoir is filled and that a supply of new, clean
brake fluid of the proper type is on hand to top off
the reservoir as the fluid level drops during bleeding.
Make sure that all the bleeding fittings are clean prior
to beginning of the bleeding procedure.
2) Bleed the hydraulic system in the following order:
A) Master cylinder bleeder fittings, if equipped.
If installing a new or rebuilt master cylinder,
follow the bench bleeding procedure which follows.
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