GMC T Series 1994 Repair Manual page 308

C. Adjust the piston pin installer (J 24086-9) to the
correct length, using the letter-number scale on
the installer adjuster (figure 11). This is neces­
sary to ensure the piston pin is pressed into the
piston to the correct depth. Refer to the instruc­
tions supplied with the tool for the proper set­
ting.
D. Lock the adjuster in place with the lock ring.
NOTICE: After the installer hub bottoms on
the support assembly, do not exceed 35000
kPa (5000 psi) pressure, as this could cause
damage to the tool.
E. Place the adjuster in the support fixture. Press
the piston pin into place (until the adjustable
installer bottoms in the support fixture).
F. Remove the piston and connecting rod assem­
bly from the tool and check the piston for free­
dom of movement on the piston pin.
Figure 12— Measuring the Ring End Gap
i
Installing the Piston Rings
Measure (Figures 4 and 12)
€
Ring end gap as follows:
1. Select rings comparable in size to the piston
being used.
2. Slip the compression ring into the cylinder bore
and press it down about 7 mm (1/4 inch) above
ring travel. Make sure the ring is square with
the cylinder wall.
3. Measure the space or gap between the ends of
the ring with a feeler gage (figure 12).
4. Refer to " Specifications" in the proper section
for correct gap.
5. If the gap between the ends of the ring is not as
specified, remove the ring and try another for
fit.
Inspect (Figure 13)
Ring fit as follows:
1. Fit each compression ring to the piston on
which it is going to be used.
2. Slip the outer surface of the top and second
compression ring into the respective piston ring
groove (figure 13), to make sure the ring is free.
If binding occurs at any point, the cause should
be determined. If binding is caused by the ring
groove, correct it by dressing the groove with a
fine cut file. If the binding is caused by a distort­
ed ring, try a new ring.
Assemble (Figures 4 and 5)
*
• All compression rings are marked on the upper
side of the ring. When installing the compression
B4979
rings, make sure the MARKED SIDE IS TOWARD
THE TOP OF THE PISTON.
• The oil control rings are 3-piece types, consisting
of two rails and an expander.
1. Expander.
2. Lower rail.
3. Upper rail.
4. Upper compression ring.
5. Lower compression ring.
• Flex all rings to make sure they are free. If
binding occurs at any point the cause should be
determined. If binding is caused by the ring
groove, correct it by dressing the groove with a
fine cut file. If binding is caused by a distorted
ring, try a new ring.
— Ring gaps must be 180 degrees apart.
— Rail gaps must be 180 degrees apart.
B5077