GMC T Series 1994 Repair Manual page 533

PISTON SELECTION
To determine the piston to cylinder bore clearance
perform the following measurements:
Measure
• Cylinder bore. Refer to " Cylinder Bores" in this
section. If the bore is serviceable, note the lowest
bore diam eter m easurement. Then compare this
measurement to the piston measurement.
• Piston as outlined under " Piston Measurement" in
this section. Compare the piston measurements to
the piston-to-cylinder-bore specifications found at
the rear of this section. Subtract the piston diame­
ter from the lowest bore diameter to determine pis-
ton-to-bore clearance.
If the used piston is not acceptable, determine if a
new piston will fit the cylinder bore by using the above
measurement procedures.
MEASURING PISTON PIN TO PISTON PIN BUSHING
CLEARANCE
IJJI Clean
Piston pin and bushing. The parts must be free of
oil and dirt.
Diameter
Measure (Figures 37, 38, and 39)
1. Piston pin diameter (figure 37). Check against
"Specifications."
2. Piston pin bushing ID. Use an inside micrometer
(figures 38 and 39).
3. Piston pin to bushing clearance. Subtract the pis­
ton pin diameter from the piston pin bushing ID.
Compare with specifications at the rear of this sec­
tion. If the clearance is excessive, try a new piston
pin. If the clearance is excessive with a new piston
pin, the connecting rod must be replaced. Replace­
ment bushings are not available.
ASSEMBLING THE PISTON AND CONNECTING
ROD
*
Assemble (Figures 40 through 44)
Tool Required:
J 39507 Piston Retaining Ring Installer
1. Piston to the connecting rod.
•T h e piston must be installed with the piston
crown indent on the same side as the connect­
ing rod bearing tang slots (figure 40).
2. Piston pin.
• Apply engine oil to the pin and push into place.
3. Retaining rings. Use J 39507 (figures 40 through
44).