30
GENERAL
30 - 14
BRAKING CIRCUIT PURGING
AIR ELIMINATION FROM THE H YDRAULIC
CIRCUIT (PURGING)
The air existence in the hydraulic circuit may be noticed by an elastic displacement of
the bra ke pedal, sometimes even, close to the floor. T his fact is more e vident with the
engine stopped.
GE NERA L RECOMMENDATIONS
Always use for completion or total changing, the brake fluid Norm SAE J 1703 , DOT 4.
In case of changing the brake fluid, it is necessary to wash the system with one liter of
industrial alcohol (diluted). Du ring the purging, the brake fluid from the reservoir must not go down bellow the
minimal level marke d on the re servoir.
To perform the operation, one person will stay on the driver place, to push the brake
pedal and the other one will perform the purging (bleeding) at the wheels using a 500 ml
vessel, a tra nsparent plastic tube and brake fl uid for completion.
NOTE
The brake fluid resulted after performing t he purging operation, IS NOT TO BE
RE-USED but only after 48 hours, in order to avoid air-bubbling ge neration on the
hydraulic circuit which shall have as effect an elastic brake pedal.
WORKING PROCEDURE
Place on the purging screw, a transparent tube with its end in a vessel with bra ke fluid
and proceed as follows: - press the brake pedal slowly, di smount t he purging screw, maintaining the full
str oke of the pedal, then tighten the screw and slowly re lease the brake pedal. Repeat the
same procedure until complete cease of air bubbles. Proceed in the same way also for the
other purgi ng places.(take i nto c onsideration t he existence all t he t ime of t he bra ke fl uid i n
the reservoi r)
Observation:
Before beginning the purging procedure, dismount the I.C.P. indicator from the pump,
which shall be remounted at the end of t he operation.
It is important to observe the fol lowing sequence of the purging places:
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