Chevrolet Light Duty Truck 1973 Service Manual page 335

Probable Cause
1. Excessive seal f r i c t i o n in power u n i t .
2. F aulty valve a c t io n .
3. Broken r e tu r n s p rin g .
Probable Cause
1. Broken valve s p rin g .
2. S t ic k in g vacuum valve.
3. Reaction diaphragm leakage.
Probable Cause
1. Brake pedal fre e play not adjusted p ro p e rly .
Probable Cause
1. Power brake t r i g g e r is out o f adjustment or bent.
2. Master c y li n d e r push rod is improperly adju ste d.
3. Power brake t r i g g e r rubber c o l l a r is missing or
damaged.
4. Binding in s id e power u n i t .
DIAGNOSIS—POWER HYDRAULIC BRAKES
SLOW BRAKE PEDAL RETURN
BRAKES GRABBY
BRAKES CHATTER: PEDAL VIBRATES (BELLOWS TYPE)
BRAKE PEDAL CHATTER (BELLOWS TYPE)
NOTE:
I f tr o u b le is determined as being caused by the power
bo oster, r e f e r to the a p p lic a b le Service or Overhaul Manual
f o r service procedures.
Remedy
1. Overhaul u n i t as o u t lin e d in the "Overhaul" Manual.
2. Overhaul u n i t .
3. Replace s p rin g .
Remedy
1. Overhaul u n i t .
2. Clean and lu b r i c a t e w ith Delco S ilic o n e Lube #5459912
(or e q u i v a l e n t ) .
3. Overhaul u n i t .
Remedy
1. A djust brake pedal f r e e play.
Remedy
1. Replace t r i g g e r and a d ju s t li n k a g e .
2. Adjust push rod.
3. Replace w ith new c o l l a r .
4. Overhaul u n i t .
BRAKES 5 -6 9
LIGHT DUTY TRUCK SERVICE MANUAL