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Brakes, Wheels and Tyres
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BRAKE BLEEDING PROCEDURE
BRAKE SYSTEM BLEEDING -
MANUALLY
Whenever any part of the brake system has been
disconnected or when the level of brake fluid in the
reservoir becomes so low as to allow air to be drawn
into the master cylinder, bleeding the air from the
brake system is required.
If brake component seals are worn or deteriorated it
is possible for air to enter the caliper piston bores
without any indication of leaking brake fluid and
thus creating a 'spongy' pedal
feel.
This spongy
pedal feel is the usual indication of air in the system.
NOTICE: It is important that cleanliness be strictly
practiced during the entire brake bleeding
procedure. Care should be exercised to ensure that
dirt or water are not allowed to enter the brake
system,
especially at the reservoir.
BLEEDING PROCEDURE
1.
Inspect brake fluid reservoir for proper fluid
level (at MAX mark) and top up if necessary
with fresh, unused brake fluid of the specified
grade
(DOT
4) (SAE 1703).
NOTICE: Never use brake fluid which has been
bled from any system to top up the fluid in the
reservoir as it may be contaminated or aerated.
NOTICE: Periodically inspect the level of brake
fluid in the brake reservoir during the bleeding
procedure. Care should be exercised not to
allow the level of fluid to drop to a point
where air could enter the hydraulic system via
the reservoir.
A clean glass container holding approximately
W
of clean, unused brake fluid (DOT 4)
should be used to receive the brake fluid being
bled from the system. In addition, the end of
the transparent drain tube should always be
immersed in this fluid during the bleeding
procedure.
When bleeding the brake system it is important
to start with the longest length of hydraulic
line first.
2.
With the engine off, remove the vacuum
reserve in the brake servo booster by applying
the brakes several times.
3. Raise car on hoist.
When bleeding all four wheels, the following
sequence MUST be followed:
A. RIGHT REAR
B. LEFT REAR
C. RIGHT FRONT
D. LEFT FRONT
4.
Install a box end wrench over the caliper
bleeder screw and install a transparent drain
hose over the bleeder screw. The drain hose
should then be placed into the receiving
container with the other end immersed in
brake
fluid.
5. Repeat the following steps for each wheel in
the sequence previously listed:
A) Fully depress the brake pedal slowly one
time and hold.
B) Loosen the bleed screw to purge the air
from the line.
C) Re-tighten the bleed screw.
D) Slowly release the brake pedal and wait 5
seconds to allow the master cylinder piston
to fully retract.
E) Repeat A through D until brake fluid
containing no bubbles emerges from
the
drain tube.
NOTICE: There may be a small amount of red
fluid discharged from the drain tube on the
initial bleeding of the brake system. This fluid is
test fluid used by the manufacturer during
production and is not harmful to the system.
NOTICE: Top-up the brake fluid reservoir as
required during the bleeding procedure
making certain air is not drawn into the
system.
6. Lower car and top up brake fluid reservoir as
required.
BRAKE SYSTEM BLEEDING-PRESSURE
TECHNIQUE
Bleeding the brake system with available pressure
bleeder tools considerably assists in performing this
procedure. These tools are equipped with brake
fluid holding tanks pressurised.
The variety of equipment consists of a holding
tank partially filled with brake fluid and a rubber
hose which is intended to be connected to master
cylinder adapter suitably designed to be installed on
specific master cylinder reservoirs. Compressed air
is then placed in the holding tank which forces the
brake fluid into the brake hydraulic system via the
master cylinder reservoir.
Pressure bleeding equipment must be of the
diaphragm type, that having a rubber diaphragm
between the brake fluid and the air supply to
prevent moisture, air or other contaminants from
entering the brake hydraulic system.
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