TM 10-3930-659-34 5-3. PISTON, CONNECTING ROD, AND CONNECTING ROD BEARING MAINTENANCE (Con’t). WARNING Dry  cleaning  solvent,  P-D-680,  is  toxic  and  flammable.  Always  wear  protective goggles and gloves, and use only in a well-ventilated area. Avoid contact with skin, eyes,  and  clothes,  and  DO  NOT  breathe  vapors.  DO  NOT  use  near  open  flame  or excessive heat. The solvent's flash point is 100°F-138°F (380C-59°C). If you become dizzy while using cleaning solvent, immediately get fresh air and medical help.  If solvent contacts eyes, immediately wash your eyes and get medical aid. 3. Using nonelectrical wire, clean oil holes and flush clean with dry cleaning solvent. Dry thoroughly with clean rags. 4. Clean connecting rod, piston pin, and piston pin bushing with dry cleaning solvent, and dry thoroughly with clean rags. 5. Inspect upper and lower main bearings for cracks, grooves, rough spots, scratches, and breaks. Remove rough spots and minor scratches with crocus cloth. Replace upper and lower main bearings if otherwise damaged. 6. Inspect piston for cracks, scoring, and excessive wear or scorching. Replace piston if badly scored. 7. Using ring groove wear gage, measure compression ring groove. If shoulders of gage touch ring land, groove is excessively worn and piston must be replaced. NOTE Piston rings come in a kit. If one piston ring requires replacement, all piston rings (compression ring, oil control ring, and oil ring expander) must be replaced. 8. Using piston ring expander, install new compression  ring  (13),  new  oil  control  ring  (14), and new oil ring expander (15) on piston (10). 9. Using   feeler   gage,   measure   compression   ring (13)    clearance.    Clearance    must    not    exceed 0.008 in. (0.203 mm). 10. Using piston ring expander, remove compression  ring  (13),  oil  control  ring  (14),  and oil expander ring (15) from piston (10). 5-27