POWER CYLINDERS 223
clearance between the ring and the top of its
groove. Record the reading.
If the measurement exceeds the specification, the
oil control ring groove is worn out. Replace the
piston. For two-piece pistons, replace only the
steel piston crown.
Piston-to-Cylinder Sleeve Running Clearance
Figure 312 Measuring piston skirt diameter
1. With the piston at room temperature, use an
outside micrometer to measure the piston skirt
diameter. Place the micrometer 90 degrees from
the piston pin bore. For one-piece pistons (466
engine), measure at 28.58 mm (1.125 in) from the
bottom of the piston. For two-piece pistons (570
engine), measure at 3.00 mm (0.118 in) from the
bottom of the piston skirt. Record the reading.
2. Subtract the measurement from the inside
diameter of the cylinder sleeve (Checking
Cylinder Sleeves, page 227). The result is the
running clearance between the piston and the
cylinder sleeve.
If the running clearance is not within the
specification for the one-piece piston, replace the
cylinder sleeve, piston and rings. For two-piece
pistons, replace the cylinder sleeve, aluminum
piston skirt, crown and rings.
Piston Rings
CAUTION: To prevent engine damage, whenever a
piston is removed from a cylinder, replace the piston
rings. Faulty piston rings cannot always be detected
by visual inspection. Therefore, if the rings are
replaced, the cylinder sleeves need to be replaced as
well.
1. Inspect the new piston rings for cleanliness. Use
a suitable solvent to clean the piston rings if
necessary.
Figure 313 Checking piston ring end gap
2. Push the piston ring down into the cylinder bore.
Make sure that the piston ring is perpendicular to
the cylinder wall.
3. Use a feeler gauge to measure the end gap
between the ends of each piston ring.
Discard any piston ring that does not meet
specifications.
EGES-265-2
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© 2009 Navistar, Inc.
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