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Brake bleeding – Mityvac MV8500 silverline elite aUtoMotive test kit User Manual

Page 21

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Form 8433

Page Number - 1

Many brake systems today feature Anti-Lock

functions and electronic controls . Many of these

systems use a high pressure electric pump to keep

the system pressurized . When bleeding or servicing,

these systems require special procedures and

cautions .

• ALWAYS observe the following precautions when

servicing Anti-Lock brake system:

• ALWAYS wear safety goggles when servicing high

pressure brake systems .

• ALWAYS depressurize the ABS system prior to add-

ing fluid or attempting service or repair .

• Unless instructed to by the manufacturer’s

procedure, NEVER open a bleeder valve or

loosen a hydraulic line while the ABS system

is pressurized .

• ONLY use recommended brake fluids . DO NOT use

silicone brake fluid in ABS equipped vehicles .

• Always refer to an appropriate repair manual for

additional information on Anti-Lock brake systems .

DEPRESSURIZING ANTI-LOCK

BRAKE SYSTEMS

Always refer to the vehicle owner’s manual or

appropriate service manual for additional

information on depressurizing procedure .

The procedure will work on most Anti-Lock brake

systems . Ensure ignition switch is in the OFF

position or disconnect the negative battery cable .

Pump the brake pedal 5 to 40 times . A noticeable

change is felt . Continue to pump the pedal a few

additional times . This should eliminate most system

pressure . Open fluid reservoir or brake lines

carefully . Top off reservoir fluid and reconnect

battery cable when finished .
BLEEDING ANTI-LOCK BRAKE SYSTEMS

Always refer to the vehicle owner’s manual or

appropriate service manual for manufacturer’s

brake bleeding procedure . The front brakes on

most Anti-Lock brake systems may be bled in the

conventional manner . Most hydraulic pump/pressure

accumulator units are fitted with a bleeder valve

which must be bled when the system has lost fluid or

is being replaced . Some vehicles require that the sys-

tem be pressurized when the rear brakes are bled .
Some automotive manufacturers use bleeding

procedures which require specialized equipment .
BRAKE LINE BLEEDING

Most low and soft pedal problems are caused by air

in the hydraulic lines, which requires bleeding of

the hydraulic system . By using the pump with brake

bleeding accessories, the system can be bled easily .

Follow a wheel-to-wheel sequence beginning with the

wheel closest to the master cylinder .
The kit provides a simple, clean, and quick method

for bleeding the fluid lines in the automotive brake

system . The creation of a vacuum in the reservoir

jar causes fluid to be drawn into the reservoir jar .

It should be noted that a tiny stream of bubbles

may be noticed in the hose after all of the air is bled

from the lines . This is caused by air seeping around

the threads of the loosened bleeder fitting and

being drawn back through the fitting by the suction

of the pump . Once the air is removed from within

the system, these tiny bubbles will in no way

jeopardize the bleeding operation, since they are

present only at the fitting and do not enter the

system . If you wish, you can put grease or Teflon

tape around the threads of the fitting to eliminate

most of the bubbles . The correct bleeding procedure

follows:
1) Always make certain that the master cylinder

reservoir is filled and that a supply of new, clean

brake fluid of the proper type is on hand to top off

the reservoir as the fluid level drops during bleeding .

Make sure that all the bleeding fittings are clean prior

to beginning of the bleeding procedure .
) Bleed the hydraulic system in the following order:

A) Master cylinder bleeder fittings, if equipped .

If installing a new or rebuilt master cylinder,

follow the bench bleeding procedure which follows .

braKe bLeeDinG