Booster Inoperative; Slow Brake Pedal Return; Grabbing Brakes - Lincoln Continental 1964 Shop Manual

2-2
GROUP 2-BRAKES
BRAKE BOOSTER TROUBLE DIAGNOSIS GUIDE
BOOSTER INOPERATIVE
SLOW BRAKE PEDAL RETURN
(OR FAIL TO RELEASE)
GRABBING BRAKES
If the preliminary tests show that
the unit is not operating, remove
the hose from the power unit and
check the vacuum source by placing
a thumb over the }lose. Remove the
thumb and note the volume of suc-
tion (gulp of air). In case of little
or no suction, check the reserve tank,
vacuum check valve, and fittings for
vacuum leaks. If no trouble is found
in the vacuum source, install the
hose, making sure there are no kinks,
and check the power unit.
Check the air cleaner to make
sure that it is clean and free of
restrictions. Remove the booster unit
This condition may result from a
clogged booster air cleaner or im-
proper master cylinder push rod ad-
justment. Refer to "Disassembly of
Booster Unit," Part 2-2, Section 4
for checking internal causes. Intern-
al causes may be a restricted air
passage, sticky valve plunger, broken
valve return spring, or the atmos-
pheric poppet valve stuck in a closed
position. The air passages should be
checked for restrictions and blown
out. The valve plunger may be
This condition may result from a
broken poppet spring or a sticking
poppet valve. Remove the booster
unit from the car as described in
Part 2-2, Section 3. Remove the
booster body from the end plate,
and disassemble the booster piston.
(006)
from the car as described in Part
2-2, Section 3. Refer to "Disassem-
bly of Booster Unit," Part 2-2, Sec-
tion 4 for the internal checks that
follow. Remove the booster body
from the end plate, and inspect the
internal vacuum hose to see that it
is properly installed and is not re-
stricted. If the hose is faulty, replace
it. Also, be sure the inside of the
body is clean. Inspect the booster
piston for faulty packing and replace
if necessary. Inspect the piston plate
attaching bolts for looseness and a
consequent vacuum leak. Tighten if
necessary. Also check the piston to
make sure it is not jammed.
touched up lightly with crocus cloth.
Do not oil. Replace if necessary.
If the return spring is broken,
weak, or distorted, it should be re-
placed. The booster piston must be
disassembled to locate and correct
the cause of a sticking poppet valve.
If the poppet valve appears faulty,
it should be replaced. Inspect the
vacuum check valve for faulty op-
eration. Be sure that the booster
piston is free to move in its normal
stroke.
Refer to "Disassembly of Booster
Unit" in Part 2-2, Section 4.
If
the
poppet return spring is broken, weak
or disturbed, replace it. If the pop-
pet valve appears worn or bent, it
should be replaced.