TM-9-2815-200-35

ENGINE, WITH CONTAINER:TURBOSUPERCHARGED, DIESEL ,FUEL INJECTION ,90-DEGREE “V” TYPE, AIR - COOLED ,12 - CYLINDER , ASSEMBLY ;MODELS AVDS-1790-2M (2815-856-4996), AVDS-1790-2A AND AVDS-1790-2AM (2815-856-9005)

TECHNICAL MANUAL; DIRECT SUPPORT, GENERAL SUPPORT AND DEPOT MAINTENANCE MANUAL INCLUDING REPAIR PARTS AND SPECIAL TOOLS LISTS

TM-9-2815-200-35 - Page 342 of 779

6-24. Cleaning

a. Pistons .

(1)

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

pins (9.2) by soaking in carbon removin g

compound, Specification MIL-S-12382 (Or d

Type 1).

Warning :

Use goggles, rubber gloves, and

rubber apron when cleaning parts in carbon

removing compound. Provide adequate ven -

tilation. Avoid inhalation of fumes and skin

contact. If compound is splashed on skin, flush

with fresh water and wash with alcohol. Alcohol

containing 2 to 3 percent camphor is preferable.

(2) Optional cleaning of the piston can be

accomplished with a vapor blast using glass

heads to provide the cleaning action and surface

roughness. A surface roughness of 50 to 100

RMS is exceptable with a RMS of 80 preferred.

If vapor blast equipment is not available, scrape

off remaining carbon deposits from piston ring

grooves with a scraper or broken piston ring. Be

careful not to scratch or gouge ring lands on

piston. Clean oil drain holes and oil ring grooves

in piston. Remove carbon from oil holes in ring

grooves.

Clean carbon from piston pins with

crocus cloth dipped in dry-cleaning solvent or

mineral spirits paint thinner.

6-25. Inspection

a. Pistons.

Inspect piston for cracks, flaws or

distortion. Use a magnifying glass and a strong

light. Small cracks will show under the light as

irregular or dark streaks. Check piston ring

grooves against limits specified in overhaul

standards (table 6-13). Inspect piston

for

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

scratches. Inspect piston pin bores for wear,

cracks, or abrasions. Replace piston if found

unserviceable.

b.

Piston

Rings.

Inspection of piston rings

rem oved from piston is not required. New rings

will be installed during piston assembly.

c. Piston Pins and Plugs.

Inspect piston pin

and plugs for cracks, nicks, or wear. Inspect end

plugs for large wear pattern and replace if found

unserviceable. Check diameter of pins against

limits specified in overhaul standards (table 6-

13).

6-48