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 551 of 779

Figure 8-4.

Figure 8-5. Checking piston position

with brass rod.

Figure 8-6. Borescope instrument in position

for cylinder bore inspection.

(6) Connect borescope control transformer

(fig. 8-4) in 110 volt electrical circuit and insert

borescope into cylinder (fig. 8-6), Visually adjust

light intensity and mirror angle until a sharp

clean image of the cylinder bore is apparent.

Inspection of the cylinder bore should be made

at three levels, lower, middle, and upper position

of the cylinder to assure maximum coverage of

the cylinder wall surface. Polish marks th e

length of the piston pin travel may be evident on

the cylinder side walls on a line parallel with the

cylinders. These lines normally are not serious

and are caused by the movement of the piston

pin allowing the pin end plugs to come in contact

with the cylinder walls. Other wear lines, surface

scratches, and wear patches that are not con-

tinuous the full length of the cylinder bore are

usually not significant.

(7) A normal shiny area will often appear at

midbore and usually on the anti-thrust side of the

bore (below exhaust valve on left bank and

below intake valve on right bank). This shiny

area will not extend the full length of ring travel

and should not be confused with scuffing of the

cylinder wall.

(8) Cylinder bores that show evidence of ¼

in. or more scuff marks, must be replaced. Re-

hone cylinders and thoroughly inspect (para 6-

31 and 6-32), dimensionally check and clean

thoroughly before reinstalling cylinders o n

engine.

Replacement cylinders will requir e

8-9