Fleet Maintenance - 25

"There are some drawbacks to both of those,"
Terry advises. "With the vacuum, a lot of times
they pull air around the bleed screw, so you're never
quite sure if you have the air bubbles out. And it
takes a long time pulling the fluid through. Pressure
methods are pretty good because you can push a
lot of brake fluid through from the top down and
its pretty quick. The only drawback to pressure is

that sometimes the air doesn't want to go down, it
wants to go up."
It was after taking these drawbacks into consideration that Phoenix Systems developed their reverse
brake bleeders, the V12 and the Max Pro HD.
"Instead of vacuuming the fluid down or pushing it
from the top down, we actually push it into the bleed
screw and it pushes the fluid from the bottom up,"

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Terry explains of the operation of the reverse brake
bleeders. "You empty the master cylinder and then
you fill it back up by pushing the fluid into the bleed
screw; that allows the air bubbles to go up the way
they naturally want to go. And it ensures that you can
have a pedal that has no sponginess that can stop the
[vehicle] the way it was meant to be stopped."
Phoenix Systems' Terry recommends that technicians reference the
vehicle owner's manual before performing a
brake bleed, as different
vehicles may require
different procedures
and sequences.
"In general, it's
usually the furthest
wheel from the master
cylinder [that you start
with]," he says.
Terry further advises
technicians to be aware
if the hydraulic braking system in service
features a proportioning
valve. As proportioning
valves keep the fluid
flowing in one direction,
from top to bottom, they
are usually restricted to
a certain psi rating. To
overcome the directional
restriction, the psi of the
brake fluid must surpass
that of the proportioning valve. Furthermore,
when bleeding brakes
on newer vehicles, it
is recommended technicians utilize a scan
tool. Scan tools can be
used to actuate ABS
sensors and other valves.
Vehicles with emergency
braking systems need
to be properly bled to
insure the emergency
braking system functions at the time of the
emergency braking
system's initiation.
The hydraulic braking
system is only as efficient as its level of maintenance. Monitoring
brake fluid and system
corrosion, maintaining
adequate brake pressure, proper lubrication,
and other best practices
applied throughout the
system will promote efficient system operation
and, in the end, prolong
the life of the system.

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Fleet Maintenance

Table of Contents for the Digital Edition of Fleet Maintenance