Chevrolet 70 1969 Series, Shop Manual

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BRAKES 5A-24
N O BOOST — H A R D P E D A L (Cont'd.)
R E M E D Y PROBABLE C A U SE
3. Air inlet blocked.
3. Replace filter. Open passages.
4. Air valve stuck.
4. Disassemble unit — clean — replace defective
parts.
5. Faulty diaphragm.
5. Replace diaphragm.
6. Faulty piston seal.
6 . Replace seal.
7. Leaks internally.
7. Rebuild.
8 . Leaking vacuum tank. 8 . Repair tank.
S L O W B R A KE P E D A L R E T U R N
PROBABLE CA U SE R E M E D Y
1. Excessive seal friction in power unit.
1. Rebuild unit.
2. Faulty valve action.
2. Rebuild unit.
3. Broken return spring.
3. Replace spring.
B R AK ES GRABBY
R E M E D Y PROBABLE C A U SE
1. Broken valve spring.
1. Rebuild unit.
2. Sticking vacuum valve.
2. Clean and lubricate.
3. Reaction diaphragm leakage. 3. Rebuild unit.
Only heavy-duty Hydraulic Brake Fluid as spe­
cified in L U B R IC A T ION (SEC. 0) should be used
in the hydraulic brake system. The use of other
fluids may cause deterioration of rubber cups
in master and wheel cylinders, and may induce
corrosion oi the metal parts of the cylinders.
CHEVROLET SERIES 70-80 H E A V Y DUTY TRUCK SH O P M A N U A L