Cleaning - TM-9-2815-200-350342

i n piston. Remove carbon from oil holes in ring

6-24. Cleaning

grooves. Clean carbon from piston pins with

a. Pistons.

crocus cloth dipped in dry-cleaning solvent or

( 1 ) Clean pistons (9.3, fig. B-4) and piston

mineral spirits paint thinner.

pins (9.2) by soaking in carbon removing

6 - 2 5 . Inspection

compound, Specification MIL-S-12382 (Ord

Type 1).

a. Pistons. Inspect piston for cracks, flaws or

d i s t o r t i o n . Use a magnifying glass and a strong

Use goggles, rubber gloves, and

Warning:

l i g h t . Small cracks will show under the light as

rubber apron when cleaning parts in carbon

irregular or dark streaks. Check piston ring

removing compound. Provide adequate ven-

grooves against limits specified in overhaul

tilation. Avoid inhalation of fumes and skin

s t a n d a r d s ( t a b l e 6 - 1 3 ) . I n s p e c t p i s t o n for

c o n t a c t . If compound is splashed on skin, flush

dam age or broken ring lands, nicks, burrs, or

w i t h fresh water and wash with alcohol. Alcohol

scratches. Inspect piston pin bores for wear,

c o n t a i n i n g 2 to 3 percent camphor is preferable.

cracks, or abrasions. Replace piston if found

(2) Optional cleaning of the piston can be

unserviceable.

accomplished with a vapor blast using glass

b. P i s t o n R i n g s . I n s p e c t i o n o f p i s t o n r i n g s

h e a d s to provide the cleaning action and surface

r e m oved from piston is not required. New rings

roughness. A surface roughness of 50 to 100

will be installed during piston assembly.

R M S is exceptable with a RMS of 80 preferred.

c . Piston Pins and Plugs. I n s p e c t p i s t o n p i n

I f vapor blast equipment is not available, scrape

a n d plugs for cracks, nicks, or wear. Inspect end

off remaining carbon deposits from piston ring

p l u g s for large wear pattern and replace if found

g r o o v e s with a scraper or broken piston ring. Be

unserviceable. Check diameter of pins against

careful not to scratch or gouge ring lands on

limits specified in overhaul standards (table 6-

piston. Clean oil drain holes and oil ring grooves

13).

6-48