Roadmaster 98300 Installation Instructions Manual - Bleed The Brakes
Bleed the brakes
After the proportioning valve is installed, bleed
the air from the valve (as described in step 12 un-
der “Install the proportioning valve”), as well as
the motorhome’s brake system, before driving the
motorhome.
Failure to bleed the brakes will cause a reduction
in braking efficiency or a complete loss of brake
pressure, which may result in property damage,
personal injury or even death.
Cautions and warnings
Follow the caution and warning below whether you
choose the specific brake line method, the traditional
method, or either of the one-person methods.
CAUTION
Check the brake fluid level often while bleeding
the brakes. Add brake fluid as necessary to prevent
the brake fluid level from falling low enough to al-
low air bubbles into the master cylinder.
If air is allowed into the brake system from the
master cylinder, all brakes, and all components con-
nected to the hydraulic brake system, must be bled.
Failure to follow these instructions may result
in a complete loss of braking pressure, which may
cause property damage, personal injury or even
death.
Wear appropriate eye protection when working on
the brake system. If brake fluid comes into contact
with your eyes, follow the manufacturer’s instruc-
tions.
Failure to follow these instructions may cause
severe eye injury.
For ABS (anti-lock braking systems)…
The front of an ABS system can be bled in the
same manner as the traditional method described be-
low. However, the rear brakes must be bled with a pres-
surized bleeder system, or, the hydraulic accumulator
must be fully charged.
The hydraulic accumulator can be charged by start-
ing the engine.
Specific brake line method
This method bleeds the air from only one wheel cyl-
inder — one of the cylinders on the brake line with the
proportioning valve.
Use the following instructions only if air has not been
allowed into the brake lines from the master cylinder.
If air has entered the brake lines through the master
cylinder, you must bleed all brake lines, and all compo-
nents connected to the hydraulic brake system — follow
the instructions under “Traditional method” (below).
Installing the BrakeMaster proportioning valve will
typically allow only a small amount of air to enter only
one of the motorhome’s brake lines. However, it must
travel from the proportioning valve to a wheel cylinder
before it can be released — in some cases, a distance
of 30 or more feet.
It is necessary to draw enough brake fluid to pull
the air to the wheel cylinder. The amount of brake fluid
that must be released will vary from one motorhome to
another, depending on the distance from the proportion-
ing valve to the wheel cylinder.
Which wheel cylinder you will bleed depends on the
type of motorhome — for Class C motorhomes, bleed the
front wheel cylinder on the brake line with the propor-
tioning valve; for Class A motorhomes, bleed the rear
wheel cylinder on the brake line with the proportioning
valve.
This method requires:
• an assistant (to pump the brake pedal)
• a box-end wrench suitable for the vehicle’s bleeder
screws (An offset wrench allows the most movement).
• a supply of brake fluid
• a disposable container
• a length of clear plastic tubing to fit over the bleed-
er screws (The tubing must have an inner diameter
which will allow it to seal over the bleeder screws).
1. First, remove the master cylinder reservoir cover
and fill the reservoir with brake fluid (if necessary) up
to the maximum marking. Reattach the cover.
Check the brake fluid level frequently while bleeding
the brakes.
2. Loosen the bleeder screw at the wheel cylinder.
Remove the rubber cap (if present).
3. Position the box-end wrench over the bleeder screw.
4. Place one end of the clear plastic tubing over the
nipple of the bleeder screw, and place the other end
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