Hydraulic System Bleeding; Installing Tool 67.7820.9519 To Adjust The Position Of The Rear Brake Pressure Regulator; Bleeding The Brake Hydro System - Lada Niva 4x4 Service Manual

Fig. 6-6. Installing tool 67.7820.9519 to adjust the position of the rear
brake pressure regulator:
1 - tool 67.7820.9519; 2 - pressure regulator control arm
Raise the protective rubber cap 6 (see fig. 6-5) and, by turn-
ing the pressure regulator on the bolts, get a slight contact
between the arm and piston 2.
Keep the regulator in this position, fully tighten bolts 1 and 7,
then apply a thin layer of greasing Ñí-1 on shaft 5 and the work-
ing part of piston 2. Fill 5-6 gr. of the same greasing in rubber cap
6 and refit.
Remove tool 67.7820.9519 and reconnect the arm end with
tie-rod 8.

Hydraulic system bleeding

Air, that got into the brake hydraulic system during replace-
ment of pipelines, hoses, sealing rings or due to system leak,
causes increase of brake pedal free travel, its "softness" and con-
siderably reduces braking efficiency.
Before bleeding the brake system ensure the leak-proofness
of all system units and their connections, check and if necessary
fill the tank with brake liquid up to normal level. Then carefully
clean from dirt and dust the bleeding connectors and remove the
protective caps.
Fit a rubber hose on the connector (fig. 6-7) for liquid drain,
and place its free end in a transparent vessel partially filled with
liquid.
Sharply depress the brake pedal 3-5 times, with 2-3 sec.
intervals, undo the connector by 1/2-3/4 turn with the pedal
depressed. Continue to press the pedal, bleed liquid with air
through the hose into the vessel. After the brake pedal will reach
the lowest front position and the liquid drain through the hose will
be finished, tightly close the bleeding connector. Repeat these
operations until all air bubbles will be bleeded from the hose.
Then, keeping the brake pedal in depressed position, tightly close
the bleeding connector and take off the hose. Wipe dry the con-
nector and refit the protective cap.
All above operations should be carried out through the upper
connectors first on the right rear wheel, the most remote from the
master cylinder, then further clockwise: the left rear wheel, left
and right front wheels. Thus, air from one circuit will be removed.
To bleed the other circuit use the lower connectors on the cylin-
der block of the left and right front brakes. Bleeding can be start-
ed from the right or left wheel.
During bleeding maintain normal liquid level in the hydraulic
system tank. If there is no air in the system the brake pedal
should go no more than 1/2-3/4 of full travel.
To exclude the influence of the servo unit and the pressure
regulator on bleeding the hydraulic system, it should be carried
out with the engine not working and rear wheels loaded (do not
raise the rear part of the vehicle).
If the brake liquid was completely drained from the system,
do the following before bleeding air:
- undo the bleeding connector by 1.5-2 turn˚ on all wheel
cylinders;
- sharply depress the brake pedal and smoothly release it,
close the connector when liquid will be drained. Then bleed the
hydraulic system, as described above.
If, despite continuos bleeding, the air bubbles still come out
from the hose into the vessel, it means air penetrates into the sys-
tem through damaged pipelines, because of insufficient tightness
of connections or due to malfunction of the master or wheel cylin-
ders.
When bleeding the vehicle, the braking system of which has
worked for a long time, renew the brake liquid.
If the brake liquid is suitable for further use, carefully filter the
liquid, and then desilt in a tightly closed vessel.
Fig. 6-7. Bleeding the brake hydro system
125