Roadmaster 98300 Installation Instructions Manual - Bleed The Brakes
the brake pedal does not provide firm resistance, there
is air in the brake line. Bleed the brake line again, as
described above.
If the brake pedal does not provide firm resistance
after the brakes have been bled, bleed the brake lines
again. Do not drive the motorhome until the brake
pedal provides firm resistance when it is depressed.
The brakes will not function at full capacity, or
may not function at all, with air in the lines. Insuf-
ficient brake pressure may result in property dam-
age, personal injury or even death.
Traditional method
Use this method if air has been allowed into the
brake lines through the master cylinder. The procedure
is identical to the “Specific brake line method” above,
except that all wheel cylinders, and any components
connected to the hydraulic brake system, must be bled.
This method also requires an assistant, and the same
tools described under “Specific brake line method.”
1. The sequence of bleeding all brake lines is deter-
mined by the location of the lines in relation to the
master cylinder — in general, always bleed the brake
line farthest from the master cylinder first, then the other
brake line in the same half of the circuit just bled:
If you know that the brake system is split front to
rear, as is the case with many rear wheel drive vehicles,
the sequence is as follows:
1. right rear
2. left rear
3. right front
4. left front
If you know that the brake system is split diagonally,
as is the case with many smaller front wheel drive ve-
hicles, the sequence is as follows:
1. right rear
2. left front
3. left rear
4. right front
2. Follow the procedures under steps 1 through 12
under “Specific brake line method” (above) for all wheel
cylinders, and any components connected to the hy-
draulic brake system.
One-person methods
There are a number of commercially-available prod-
ucts which allow one person to bleed the brake lines.
They use two general methods — vacuum bleeding and
pressurized bleeding
Vacuum bleeding systems use a vacuum to draw
the air out of the brake system, eliminating the need
for an assistant. Typically, a tube runs from the bleeder
valve to a sealed container. Another tube runs from the
continued on next page
Bleed the brakes
Figure 11
Specific brake line method
continued from previous page
of the tubing into the disposable container.
5. Instruct the assistant to “apply.” The assistant should
pump the brake pedal three times, then hold the pedal
down firmly, and respond with “applied.”
6. Loosen the bleeder screw with a brief quarter turn,
just enough to allow a solid stream of brake fluid to
flow through the tubing. (The brake pedal will “fall” to
the floorboard as the bleeder screw is opened. Instruct
the assistant in advance not to release the brakes until
instructed.)
Watch for air bubbles in the brake fluid as it empties
into the disposable container. This is the air that was
allowed into the system when the proportioning valve
was installed.
7. When these air bubbles have emptied into the con-
tainer, close the bleeder screw by tightening it gently.
8. Instruct the assistant to “release” the brakes.
Note: do not release the brake pedal while the bleed-
er screw is open — air will be pulled into the system.
The assistant should respond with “released.”
9. Depending on the distance from the proportioning
valve to the wheel cylinder, it may be necessary to
repeat the “apply” and “release” sequence. Continue
to do so until air bubbles are no longer present.
Check the brake fluid level in the master cylinder
reservoir after each sequence. Add fluid, as necessary,
to keep the level at the maximum marking.
When the brake line has been bled, check and refill
the master cylinder reservoir again, if necessary.
10. Replace the rubber cap you removed earlier (if one
was present).
11. Inspect the bleeder screw and other fittings for leaks.
Correct, if necessary. Inspect the proportioning valve
and the brake line fittings at the six points indicated in
Figure 11 and correct, if necessary.
12. Depress and release the brake pedal several times
— it should feel firm and solid when it is depressed. If
10