GMC 1982 Light Duty Truck, Service Manual

Page: 134 / 1435

1D-18 AIR CONDITIONING COMPRESSOR OVERHAUL
Fig. 1D-44 Checking A-6 Piston and Shaft End Play
CHECKING FOR
REAR
THRUST
AND RACE
THICKNESS
FRONT THRUST
GIVES PROPER
HEAD CLEARANCE
CHECKING FOR SHOE
THICKNESS “X”
204980
Fifteen (15) th ru st races are provided in increm ents of
.Olmm (.0005") (one-half thousandths) thickness and one
Z E R O gage thickness, providing a total o f 16 sizes available
for field service. T he th ru st race “ num ber” also corresponds
to the last three digits o f the piece part num ber. See T hrust
R ace Size C h art in Fig. ID-41.
22. Rem ove nuts from top plate of Com pressing Fixture
J 9397, and remove top plate.
23. Separate cylinder halves while unit is in Fixture. It
m ay be necessary to use a wooden block and mallet.
24. Rem ove R ear C ylinder H alf and carefully remove
one piston at a tim e from axial plate and front cylinder half.
D o not lose the relationship o f the front ball and shoe disc
and rear ball. T ransfer each piston, ball and shoe disc to its
proper place in P arts T ray J 9402.
25. Now rem ove rear o u ter zero th ru st race (it will be
on top) from shaft and install the th ru st race ju st selected
in Steps 20 and 21 th a t is presently setting in the right-hand
slot at bottom center of P arts T ray J 9402.
The rem oved zero th ru st race may be put aside for re­
use in additional G aging or rebuilding operations.
A-6 COMPRESSOR CYLINDER AND
SHAFT ASSEMBLY
A -6 T e flo n P iston Ring R ep la c em en t
The Teflon piston ring installing, sizing and gaging
tools are shown in Fig. ID -45.
1. Rem ove the old piston rings by carefully slicing
through the ring w ith a knife or sharp instrum ent, holding
the blade alm ost flat w ith the piston surface. Be careful not
to dam age the alum inum piston or piston groove in cutting
to remove the ring. Exercise personal care in cutting the
piston ring for rem oval to prevent injury.
2. Clean the piston and piston ring grooves with
trichloroethane, naphtha, Stoddard solvent, kerosene or
equivalent solvent and blow the piston dry w ith D R Y air.
3. Set the piston on-end on a clean, flat surface and
install the Ring Installer G uide J 24608-2 on the end of the
piston (Fig. ID-46).
4. Install a Teflon ring on the Ring Installer G uide J
24605-2 as shown in Fig. ID -47, w ith the dished or dull-side
down and glossy-side up.
5. Push the Ring Installer J 24608-5 dow n over the
Installer G uide J 24608-2 to install the Teflon ring in the
piston ring groove (Fig. ID-47). If the Teflon ring is slightly
off position in the ring groove, it can be positioned into place
by fingernail or blunt-edged tool th a t will not dam age the
piston.
T he R ing Installer J 24608-5 will retain the Installer
G uide J 24608-2 internally when the Teflon ring is installed
on the piston. Remove the Installer G uide from the Ring
Installer and do not store the installer guide in the ring
installer, as the Ring Installer Segment R etainer O -Ring J
24608-3 will be stretched and possibly weakened during
storage. This could result in the O -R ing J 24608-3 not
holding the Ring Installer segm ents tight enough to the
Installer G uide J 24608-2 to properly install the Teflon ring
on the piston.
6. L ubricate the piston ring area w ith 525 viscosity
refrigerant oil and rotate the Piston and Ring Assembly into
the Ring Sizer J 24608-6 at a slight angle (Fig. ID -48).
R otate the piston, while pushing inw ard, until the piston is
inserted against the center stop of the R ing Sizer J 23608-6.
NOTICE:
D O N O T push the Piston and Ring
Assem bly into the Ring Sizer J 24608-6 w ithout proper
positioning and rotating as described above, as the ends
o f the needle bearings of the R ing Sizer m ay dam age
the end o f the piston.
7. R otate the Piston and Ring Assembly in the Ring
Sizer J 24608-6 several com plete turns, until the Assembly
rotates relatively free in the Ring Sizer (Fig. ID-48).
8. Rem ove the Piston and R ing Assembly, wipe the end
o f the piston and ring area w ith a clean cloth and then push
the Piston and Ring Assembly into the Ring G age J 24608-1
(Fig. ID-49). The piston should go through the Ring Gage
w ith a 2 to 8 lb. force or less w ithout lubrication. If not,
repeat Steps 6 and 7.
9. Repeat the procedure for the opposite end of the
piston (Fig. ID-50).
NOTICE:
D O N O T lay the piston down on a dirty
surface w here dirt or m etal chips m ight come into
contact and become im bedded in the Teflon ring
surface.
10. L ubricate both ends o f the piston w ith 525 viscosity
refrigerant oil before inserting the piston into the cylinder
bore.
NOTICE:
Reasonable care should be exercised in
installing the piston into the cylinder bore to prevent
dam age to the Teflon ring.
A-6 COMPRESSOR INTERNAL
CYLINDER AND SHAFT ASM.
A ssem b ly
A fter properly perform ing the “ G aging Procedure,”
choosing the correct shoe discs and th ru st races, and