While some may think an old school "flush" will
breathe new life into a braking system,
Chuck Kennedy, technical
trainer at
Bendix Brakes says if one is
performed without checking for contaminants
already present, the braking system's hydraulic
control unit (HCU) can be seriously damaged.
That's why maintaining clean, contaminant-free
brake fluid is just as important to a vehicle
as getting regular oil changes.
“Contaminated brake fluid is one of the top
reasons for hydraulic control unit failure in
today’s brake systems. It’s critical to remove
old fluid from the reservoir and clean the
reservoir itself before adding fresh fluid.
This keeps contamination from spreading to
sensitive areas,” Kennedy said. “A flush takes
what’s already in the master cylinder reservoir
– including any sediment or solid particulates
– and pushes it through the hydraulic control
unit before going out of the calipers and wheel
cylinders. Inlet solenoid screens will trap
particles that haven’t been removed, and if a
wheel circuit is plugged, it will usually need
to be replaced.”
As technicians know, it’s expensive to replace
hydraulic brake components, and repairs can be
easily avoided by just making a quick visual
check for sediment and solid deposits.
Technicians may also want to consider using
test strips and electronic moisture testers.
If test strips are used, they should be kept
tightly sealed to maintain accuracy.
Electronic testers are more expensive, but also
more accurate.
Once particles and other contaminants
have been removed, fresh fluid can be bled
through the rest of the system, or a full brake
fluid change can be performed.
Kennedy advises that an HCU bleed function
performed during a fluid change with a bi-
directional scan tool will also insure that all
fluid is changed, not just what’s in the main
wheel circuit galleys.
Preventative maintenance goes a long way in
keeping today’s complex braking systems fully
operational, says Kennedy.
For more maintenance tips and information,
visit www.bendixbrakes.com.
For more information, log on to
www.bendixbrakes.com.
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