Pontiac tempest 1968 Service Manual page 188

DELCO-MORAINE P O W E R B R A K E
5
A - 5
MASTER
CYLINDER
F R O N T
HOUSING
FRONT
HOUSING SEAL
POWER PISTON
ASSEMBLY
POWER
P I S T O N B E A R I N G
V A C U U M CHECK
VALVE
PUSH R O D
BOOT
CHECK VALVE
GROMMET
CLEVIS
POWER PISTON
RETURN SPRING
SILENCER
F i g . 5 A - 6 Exploded View of Pontiac Power Brake Unit
ages. If inside of front housing is slightly scored or
scratched, clean with crocus cloth or fine emery
cloth. If scratches in front housing cannot be re­
moved, replace housing.
CAUTION: It is important that all parts be placed
on a clean paper after being cleaned to prevent the
possibility of dirt being assembled into unit or
grease contacting any rubber parts.
POWER BRAKE
Inspect all parts for scoring, pitting, dents or
nicks. Small imperfections can be smoothed out with
fine emery cloth. Replace if badly nicked, scored or
otherwise damaged.
MASTER CYLINDER
Inspect bore from the open end. The bore should
be free from scores, deep scratches and corrosion.
If it appears that corrosive brake fluid has damaged
the bore, replace damaged parts and flush out entire
brake system including wheel cylinders.
The sealing surfaces should be clean and smooth.
Check for cracks and damaged threads. Be sure that
the by-pass and compensating ports to the master
cylinder are not restricted.
Check for distortion of all springs and deteriora­
tion of all rubber parts. Any evidence of soft or
swollen rubber parts indicates contaminated brake
fluid requiring flushing of the entire brake system
and replacement of wheel cylinder cups, as well as
all rubber parts in master cylinder.
AIR FILTER
Replace air filter element if dirty. Do not clean.
ASSEMBLE BRAKE UNIT
MASTER CYLINDER-ASSEMBLE
Refer to Section 5 - Standard Brakes for assembly
procedures.
POWER PISTON-ASSEMBLE
1. Place a new O-ring seal in groove on vacuum