TM 5-3895-346-14
ENGINE OVERHAUL
PISTON AND PISTON RINGS
Figure 5. Removing or Installing
Figure 6. Location of Joint in Piston
Piston Pin Bushings
Pin Bushings
b.
Place the piston in the fixture and insert the pilot end of reamer J 4970-4 through the
clamping bar, bushings, and into the guide bushing.
c.
With the piston, fixture, and reamer in alignment, tighten the wing- nuts securely.
d.
Ream the bushings (Fig. 7). Turn the reamer in a clockwise direction only when reaming or
withdrawing the reamer. For best results, use only moderate pressure on the reamer.
e.
Withdraw the reamer and remove the piston from the fixture. Blow out the chips and
measure the inside diameter of the bushings. The diameter must be 1.3775 to 1.3780
inches.
Fitting Piston
Measure the piston skirt diameter lengthwise and crosswise of the piston pin bore. Measurements should be
taken at room temperature (70 or 21 ). The taper and out-of-round must not exceed 0.0005 inches. Refer
F
C
to Specifications for piston diameter specifications.
A new cylinder liner has an inside diameter of 3.8752 to 3.8767 inches. The piston-to-liner clearance, with new
parts, is 0.0031 to 0.0068 inch (non-turbocharged engines) or 0.0061 to 0.0098 inch (turbocharged engines). A
maximum clearance of 0.010 inch (non-turbocharged engines) or 0.012 inch (turbocharged engines) is
allowable with used parts.
With the cylinder liner installed in the cylinder block, hold the piston upside down in the liner and check the
clearance in four places, 900 apart (Fig. 8).
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