Brake
bleeding is a process performed on a hydraulic brake system when the brake
pipes and hoses that contain the brake fluid are cleansed of air bubbles that
greatly reduce its efficiency. This process is thus a maintenance activity and
is performed by forcing clean, bubble free brake fluid through the entire
braking system from the master cylinder to the disc brakes. One brake bleeder
tool is the brake bleed screw which is normally mounted at the highest point on
each cylinder.
There
are four main ways to brake bleeding that require suitable brake bleeders.
These are: pump & hold, vacuum, pressure and reverse pressure methods. In
the first method, the pump & hold one, one person pumps the brake pedal to
compress the air and then holds the pressure, The other person opens the brake
bleeder valve and let out all fluid and air, closes the valve after the pedal
has landed to prevent air from being sucked back in. This process is repeated
many times and for each wheel. A clear tube is attached to the valve and onto a
container to collect the brake fluid. This method of cleaning the brake fluid
can also be handled by an individual who uses a `one man’ brake bleeder tool
that consists of a one way valve at the end of a tube which is attached to the
bleeder valve. Sometimes this does not work as the air is sucked back in
through the threads of the valve. A good way to counter this is by sticking
Teflon tape on the threads.
Another
important method for brake bleeding is the vacuum method. Here, the main
cylinder is topped off and the cover loosened. A special vacuum pump is
connected to the brake bleeder valve and all the brake fluid is pulled out till
it runs clear of bubbles. The last method is via pressure wherein a specialized
pressure pump is attached to the master cylinder. The pump is pressurized and
the brake bleeder valve is opened one at a time till the brake fluid is clear
of air.
To
make this task easier, the following brake bleeder equipment is essential:
1.
A 10 mm box wrench for disc brakes and an 8mm box wrench for drum brakes.
2.
A can of brake fluid
3.
Turkey
4.
Clear plastic tubing
5.
A can of brake cleaner
6.
A car lift or four jack stands
A
socket set consists of a socket wrench, an extension and a number of sockets.
This is basically for those who like to carry out minor repairs at home
themselves. The tools come in a variety of configurations and two main sizes –
big set for those who build and repair automobiles after a mishap and the small
set for easy to repair functions at home e.g. loosening or tightening a nut or
bolt on furniture or kitchen equipment.