Release the brake pedal.
If either one or both of the stroke
indicators do not retract, this is an
indication that a bypass opening in one of
the master cylinders is closed by dirt,
corrosion or the primary cup has become
A primary cup which has become too
large is an indication of wrong or
dirty hydraulic fluid in the system. If
hydraulic fluid is dirty, remove and
hydraulic system of the brakes.
Flush the brake lines with clean
Check for Leakage
Push brake pedal down and keep it in that
Put soap suds on the connections of the air lines
at the master cylinders and check for air
Release the pedal.
Put soap suds on the exhaust openings of the
control valve for the brakes.
When the pedal is pushed down, leakage must
not be more than a 1.00 in. (25.4 mm) soap
bubble in one minute.
Repair any air leaks that are found.
HYDRAULIC BRAKE SYSTEM SERVICING
Use heavy duty hydraulic brake fluids meeting SAE
J1703C specifications only. Other fluids may cause
damage to rubber parts.
Do not let dirt or other material get in the brake fluid
when the hydraulic brake system is serviced. Most parts
cleaners may be used to clean master cylinders and
wheel cylinders if the parts are then thoroughly washed
with denatured alcohol or brake fluid to remove all of the
solvent. After removal of the solvent, dry parts and
protect from dust until cylinders are reassembled. Wash
the rubber parts in clean denatured alcohol or brake
Do not use mineral base cleaning
solvent such as gasoline, kerosene,
acetone, paint thinner, etc. These
solvents will damage rubber parts
and cause them to become soft and
of no use.
AIR REMOVAL FROM BRAKES
(Bleeding the Brakes)
VALVES THAT LET THE AIR OUT (WATER
DISTRIBUTOR BRAKES) (Bleed Screws)
Let the air out of system for the wheel brakes which
is activated by the master cylinder.
Check the fluid level in the reservoir. The
primary level must be .5 in. (12.7 mm) from the
top of the reservoir.
To keep air out of the master
cylinder, fluid must always be seen
in the reservoir while air is being let
out of the system. When filling an
empty system, loosen the caps on
comes out, then tighten the caps.
VALVES THAT LET THE AIR OUT (TRACTOR
BRAKES) (Bleed Screws)