Mityvac 06820 Diesel Compression Test Adapters - Manual (Page 21)

Page Number - 21
Form 822378
4) By closing the valve and repeating
the process, all of the air should be
eliminated from the system. Stop and
add more fluid when master cylinder
gets low.
5) Top off and recap the reservoir.
TROUBLESHOOTING
1) If, after bleeding procedure, the brake
continues to be unresponsive, you
may have water in the system, in
which case it will need to be disas-
sembled and cleaned by a qualified
service technician.
2) If the brake squeaks slightly after
bleeding, the disc and pads must be
cleaned.
3) Although DOT 3 fluid is recommended
by most manufacturers, it has a
tendency to collect moisture - which
causes the common discoloration you
see - and that means decreased
efficiency. DOT 5 is silicone based
and does not have the same tenden-
cy to collect moisture. It also has a
higher tolerance. DOT 5, however, is
not always easy to find and the two
types of fluid must not be mixed.
4) Rubber hoses are supplied stock on
most motorcycles, but they have a
tendency to expand, which may
result in a spongy brake feel after a
lot of riding. Braided steel line will not
expand like this.
There is also a hose adapter and
5/32” ID hose in the kit for bleeding
hydraulic motorcycle brakes. Be sure
the caliper and master cylinder
pistons are free and all fittings are
tight. Cover the gas tank with rubber
or plastic protective sheet.
Connect the adapter and 5/32” ID
hose to the end of the long tube and
connect to caliper bleeder fitting.
Bleed as with an automobile.
BENCH BLEEDNG THE
MASTER CYLINDER
Whenever a master cylinder has been
removed from a vehicle or a new one is
being installed, the master cylinder must
be bench bled. Failure to bench bleed is
the main reason for unsuccessful master
cylinder replacement. Bench bleeding
greatly decreases the chance that any
air will be caught in the cylinder upon
reinstallation. This bleeding technique
utilizes this Kit. Follow this procedure:
1) Plug outlet holes of the master
cylinder and gently clamp it in a
vise with the push rod end slightly
elevated. NOTE: Damage may
result if master cylinder is clamped
by the bore or if reservoirs are
clamped too tightly.
2) Fill the master cylinder with an
approved type brake fluid and keep
it filled at all times during the
procedures.
3) Remove a plug from the master
cylinder and attach the proper
adapter to this master cylinder
outlet port. Connect the pump tube
to the reservoir jar and the jar tube
to the adapter (FIGURE 16).
4) Pump the pump and observe air
and fluid flowing into the reservoir
until clear, bubble-free fluid
appears.
5) Plug the outlet tightly and repeat
step 4 on the other outlet ports.
6) Clamp master cylinder in a vise
with the push rod end down
slightly. Slowly slide the master
cylinder push rod back and forth
about 1/8”, until no air bubbles can
be seen in the reservoirs.
7) Remount the master cylinder with
the push rod end up and follow
steps 3 & 4 on all outlet ports. Plug
ports tightly. The master cylinder is
now free of air and ready to install.