Cleaning. - TM-9-2815-200-350348

c. S o a k c y l i n d e r i n c a r b o n r e m o v i n g c o m -

b. Value Rocker Arm Covers. Refer to

paragraph 4-14.

pound to remove carbon and other foreign

6-30. Cleaning.

material from dome, valve ports, and the area

between the top of the barrel and the head

a. C l e a n c y l i n d e r a n d a s s o c i a t e d p a r t s , a n d

casting.

remove heavy carbon deposits from combustion

6-31. Inspection

c h a m b e r with a scraper or blunt tool which will

n o t nick or scratch the surface, Remove only the

a. Valve Guides. Inspect valve guides (14 and

heavy carbon deposits. Surface need not be

37, fig. B-4), for cracks, galling, erosion, or

cleaned to a mirror finish.

s c u f f i n g . Check guides for secure fit in cylinder.

b. Clean carbon from fuel injector nozzle seat

Check guides against limits specified in the

using nozzle carbon cutter - 4910-795-7958 as

overhaul standards (table 6-15).

shown in figure 6-50.

Note. Do not remove valve guides unless

replacement is necessary.

b. Valve Seat Inserts. Check valve seat inserts

f o r secure fit in the cylinder (41, fig. B-4). In-

serts must have tight fit. Inspect inserts for

burned or pitted surfaces. Check valve seat

contact by lightly bluing face of insert with

Prussian blue - 8010-247-8706 and placing a

new valve into position on valve insert. Rotate

valve one-half turn on insert and check valve seat

f o r Prussian blue contact. Valve seat must show

perfect contact, as indicated by Prussian blue

transfer, to qualify as a serviceable insert. Inserts

that do not show perfect contact must be marked

for repair. I f inserts are cracked, loose, or

damaged beyond repair, the cylinder must be

replaced. I f valve seat inserts can be made

serviceable by grinding; repair as outlined in-

paragraph 6-33a(2). Check the inserts against

limits specified in overhaul standards (table 6-

15).

c. Cylinder. Two types of cylinders have been

F i g u r e 6-50. Clean ing carbon deposits from

used on the ADVS-1790 series engines. The

fuel injector nozzle seal using nozzle carbon

latest type cylinder has a wall thickness in-

cutter - 4910-795-7958.

creased by 0.030 inch to provide greater

strength. These cylinders can be identified by a

m a c h i n e d groove o n the cylinder mounting

flange periphery, refer to figure 6-51.

6-54