5-7.5.5. Thoroughly clean the cylinder of any accumulated oil, using a non-flammable safety
solvent. P a y particular attention to the cleaning of the cylinder bore. Make sure the
cylinder-to-frame gasket surf aces are thoroughly cleaned of any gasket particles.
5-7.5.6. Thoroughly clean the piston of any accumulated oil, using a non-flammable safety
solvent. Pay particular attention to the cleaning of the piston ring grooves and the oil return
holes in the oil control wiper ring grooves.
5-7.5.7. Inspect the cylinder bore for any signs of scoring and scuffing. If the cylinder bore
shows any signs of being scored or worn, as indicated by visible ridging at the end of the ring
travel, it must be replaced; otherwise, effective oil control will not be established even with
the new piston rings.
5-7.5.8. Inspect the piston for any signs of scoring or for any indication of cracked or broken
lands which would require replacement of the pistons. If the piston shows no signs of being
scored or of having any cracked or broken lands, check the general condition of the ring
grooves for any signs of excessive wear. Wearing of the ring grooves may cause "tapering"
of the grooves, which would result in excessive clearance between the piston rings and their
corresponding grooves.
5-7.5.9. Assemble the new piston rings on the piston by first applying compressor lubricat-
ing oil to the piston ring grooves. To eliminate the possibility of breaking or distorting a
piston ring, always use a piston ring expander and never pass one ring over another. If a
piston ring expander is not available, spread the piston rings only far enough to allow them to
be placed over the piston. The bottom oil control wiper ring is always installed first and then
the adjacent one, then each compression ring on up to the top. Refer to Paragraphs 5-7.6,
5-7.7 and 5-7.8 for details on installation of rings.
5-7,5.10. After all of the piston rings have been installed on the piston, it may then be re-
placed on its corresponding connecting rod.
5-7.5.11. When a new replacement piston ring set has been installed and the original cylin-
der is to be reused, the cylinder wall must be "deglazed" or slightly roughened to provide a
proper, "seating-in" surface for the piston rings. Use a No. 80 grit abrasive cloth and go
over the cylinder wall using a rotating and reciprocating motion. The abrasive cloth should
be wetted with some type of oleum spirits or safety solvent during deglazing to reduce the
harshness of its surface and to keep feathered edges to a minimum. Do not overdo the de-
glazing; dulling the glaze is usually sufficient and can be accomplished with a very light pres -
sure. After deglazing, the cylinder wall should be thoroughly cleaned by scrubbing the bore
with a good stiff bristle (not wire) brush, using ordinary soap or detergent and hot water.
Rinse thoroughly with hot water and then check the cleanliness of the cylinder bore by wiping
with a soft white paper cloth. If the paper shows more than slight discoloring, the cylinder
bore has not been completely cleaned.
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