Chevrolet 1977 10 Series, Repair Manual, Page: 361 / 468

AUTOMATIC TRANSMISSIONS
(400)7A-41
INSPECTION OF MODULATOR
AND VALVE
1. Inspect m odulator assembly for any signs of bending
or distortion (Fig. 7A-134C).
2. Inspect "O" ring seal seat for damage.
3. Apply suction to vacuum tube and check for
diaphragm leaks.
4. Check m odulator bellows as outlined in Section 7 of
Service M anual (m odulator plunger is under pressure - 16
lbs.). If bellows is damaged plunger will have very little
pressure.
5. Inspect m odulator valve for nicks or damage.
6. Check freeness of valve operation in case bore.
INSPECTION OF M AN UAL AND PARKING
LINKAGE
1. Inspect parking actuator rod for cracks, or broken
spring retainer lugs (Fig. 7A-135C).
2. Inspect actuator spring for damage.
3. Inspect actuator for free fit on actuator rod.
4. Inspect parking pawl for cracks or wear.
5. Inspect manual shaft for damaged threads, rough oil
surface or loose lever.
Fig. 7 A-1 3 4 C ~ M o d u la to r A s s e m b ly and V a lve
6. Inspect inside detent lever for cracks or a loose pin.
7. Inspect parking pawl shaft if removed for damaged
retainer groove.
8. Inspect parking pawl return spring for deformed coils
or end.
9. Inspect parking bracket for cracks or wear.
10. Inspect detent roller and spring assembly.
MODULATOR VALVE
OIL RING
MODULATOR ASSEMBLY
Fig. 7A-135C ~Manual and Parking Li nkage-Exploded Vie w