GMC T Series 1994 Repair Manual page 739

CONTROL VALVE ASSEMBLY/ACCUMULATOR
HOUSING
77
Figures through 80
NOTICE:
The use of a honing stone, fine sandpaper
or crocus cloth is not recommended for servicing
stuck valves. All valve lands have sharply machined
comers that are necessary for cleaning the bore. If
these comers are rounded, foreign material could
wedge between the valve and the bore causing the
valve to stick. If it is found necessary to clean a
valve, micro fine lapping compound 900 grit (J
38459) or finer should be used.
Too much lapping of the valve will cause excessive
clearances and increase the chance of a valve not
operating.
p y | Clean
• Control valve assembly and accumulator housing
(51) thoroughly in clean solvent.
• Air dry.
ACCUMULATOR HOUSING ASSEMBLY
77
Figures and 78
Disassemble
m
77
Figure
1
Five bolts (53), using 8 mm socket.
.
2. One bolt (52), using 8 mm socket.
3. Accumulator housing assembly.
4. Gasket accumulator housing (47).
5. Spacer plate (46).
6. Gasket (45) valve body spacer.
7. Gasket (48) accumulator housing to spacer plate.
Disassemble
Figure 78
1 Torque signal compensator valve (409) and spring
.
(410).
Snap ring (402) from outside housing, pin (408),
2.
snap ring (402), piston (407) and spring (49).
3. 3rd clutch piston (405) and spring (50).
4. Seals (404 and 406).
l2 l
Clean
• All components.
o s
Inspect
All valves, pistons, springs and seals for:
• Porosity.
• Scoring.
• Nicks.
• Scratches.
Assemble
• Accumulator housing assembly components
exactly as shown. Notice the positions of the
valve and pistons.
CONTROL VALVE ASSEMBLY
|<f»| Disassemble
Figure 77
• Control valve assembly.
A. Position as shown on a clean surface.
B. Remove valve trains.
CAUTION: Some valves are under
pressure - cover the bores while removing
the roll pins or personal injury could
result.
C. Remove blind hole roll pins with a drill bit.
D. Valves, springs, bushings and pistons must
be laid out on a clean surface.
Clean
• All valves, springs, bushings, pistons, control
valve body and accumulator housing in clean
solvent.
• Dry using compressed air.
| y | Inspect
1. All valves, pistons and bushings for:
• Porosity.
• Scoring.
• Nicks.
• Scratches.
2. Pistons for:
• Seal damage.
3. Springs for:
• Damaged or distorted coils.
4. Valve body casting and accumulator housing for:
• Porosity.
• Cracks.
• Interconnected passages.
• Damaged machined surfaces.
5. Solenoid, connectors and switches.
6. Pulse width modulated (PWM) solenoid screen
(75).