Buick LeSabre 1965 Service Manual page 536

9 - 1 4 SERVICE
BRAKES
SECTION 9-C
BRAKE SERVICE, ADJUSTMENT, REPAIR PROCEDURES
Paragraph
CONTENTS OF SECTION 9-C
Subject Subject Page
9-6 Filling, Bleeding, Flushing
Brake Hydraulic System 9-14
9-7 Brake Adjustment 9-15
9-8 Parking Brake Adjustment -
Cable Lubrication 9-16
9-9 Replacing Brake Pipes 9-17
9-10 Replace or Reline Brake Shoes -
Repair Brake Linings 9-17
9-11 Inspecting and Reconditioning
Brake Drums 9-20
9-12 Brake Wheel Cylinder Overhaul . . 9-21
9-13 Brake Master Cylinder Overhaul . . 9-21
9 - 6 FILLING, BLEEDING,
FLUSHING BRAKE
HYDRAULIC SYSTEM
a. Filling Brake Master
Cylinder
The master cylinder must be kept
properly filled to insure adequate
reserve and prevent air from en-
tering the hydraulic s y s t e m .
Avoid overfilling.
On a l l cars (with regular or
power brakes), the brake fluid
reservoir is on the master cylin-
der which is located under the
hood on the left side.
Thoroughly clean reservoir be-
fore removal to avoid getting dirt
into reservoir. Add fluid as re-
quired to bring level 1/8" below
lip of reservoir opening. Use
Delco Super No. 11 Hydraulic
Brake Fluid or equivalent.
CAUTION: Do not use shock ab-
sorber fluid or any other fluid
which contains mineral oil. Do
not use a container which has
been used for mineral oil. Even a
trace of mineral oil will cause
swelling and distortion of rubber
p a r t s fn the hydraulic brake
system.
Check for clear vent holes in
filler cap and make sure dia-
phragm is in good condition before
installing retaining bail.
b. Bleeding Brake Hydraulic
System
A bleeding operation is necessary
to remove air whenever it is in-
troduced into the hydraulic brake
system. Since air is compressible
and hydraulic fluid is not, the
pressure of air in the system is
indicated by a springy, spongy
feeling on the brake pedal ac-
companied by poor braking action.
Air will be introduced into the
hydraulic system if the brake
pedal is operated when the fluid
is too low in master cylinder
reservoir. Air will also enter the
system whenever any part of hy-
draulic system is disconnected.
It will be necessary to bleed the
hydraulic system at all four wheel
cylinders if air has been intro-
duced through low fluid level or
by disconnecting brake pipe at
master cylinder. If brake pipe is
disconnected at any wheel cylin-
der, then that wheel cylinder only
need be bled. If pipes are dis-
connected at any fitting located
between m a s t e r cylinder and
wheel cylinders, then all wheel
cylinders served by the discon-
nected pipe must be bled. See
Figures 9-5 and 9-6.
c. Sequence of Bleeding
Wheel Cylinders
It is advisable to bleed one wheel
cylinder at a time to avoid getting
fluid level in reservoir danger-
ously low. The correct sequence
of bleeding is left front, right
front, left rear, right rear. This
sequence expels air from the
lines and wheel cylinders nearest
to the master cylinder first, and
eliminates the possibility that air
in a line close to the master cyl-
inder may enter a line farther
away after it has been bled.
CAUTION: Do not perform bleed-
ing operation while any brake
drum is removed.
d. Bleeding Wheel Cylinder
Without Pressure Tank
1. Fill master cylinder (subpar.
a, above).
2. Install Wrench J-21472 on
bleeder valve. Slip a brake
bleeder tube over ball of wheel
cylinder bleeder valve. Place
lower end of bleeder tube in a
clean glass jar that is partially
filled with clean brake fluid. Po-
sition end of tube so that it will
remain submerged under fluid
during bleeding operation. Un-
screw bleeder valve 3/4 of a
turn. See Figure 9-10.
3. Depress brake pedal a full
stroke, then allow pedal to return
slowly to released position. Al-
lowing pedal to return quickly
may draw air into system. Con-
tinue operating pedal in this man-
ner until fluid flows from bleeder
tube into glass jar in a solid
stream that is free of air bubbles,