Inspection - TM-10-3930-634-340058

TM 10-3930-634-34

straight fluted reamer inside ring bore in injector

(t) Inspect injector plunger for scoring, erosion,

chipping or wear. Check for sharp edges on that

body. Turn reamer in a clockwise direction and remove

any burrs inside ring bore. Wash injector body in clean

portion of the plunger which rides in the gear. Remove

fuel oil and dry with compressed air.

sharp edges with a 500 grit stone. Wash plunger after

(k) Carefully insert carbon removal tool in the

stoning it. Use the injector bushing "Inspectalite" to

injector nut as illustrated in figure 3-47. Turn the

check plunger bushing for cracks or chipping. Check

reaming tool in a clockwise direction to remove the

locating pin in bushing. If pin is damaged or sheared

carbon deposits on spray tip seat. Remove the carbon

off, it must be replaced. Slip plunger in bushing and

deposits from the lower end of the injector nut as

check for free movement. Badly worn, chipped or

s c o r e d plungers or bushings must be replaced.

shown in figure 3-48. In the same manner, use care to

Plungers and bushings are mated parts and must be re-

avoid removing any metal or setting up burrs on the

placed as an assembly.

spray tip seat.

(l) Wash injector nut in clean fuel oil and dry

(g) Injector plungers cannot be reworked to

change output. Grinding will destroy the hardened

with compressed air. Carbon deposits on the spray tip

case at the helix and result in chipping and seizure or

seating surfaces of the injector nut will result in poor

scoring of plunger.

sealing and consequent fuel leakage around the spray

tip.

(h) Examine spray tip seating surface of injector

(m) When handling injector plunger, do not

nut for nicks, burrs, or brinelling. Reseat the surface

or replace nut if it is severely damaged.

touch the finished plunger surfaces with your fingers.

(i) Inspect sealing surfaces of injector parts in-

Wash plunger and bushing with clean fuel oil and dry

dicated by arrows in figure 3-49. Examine the sealing

with compressed air. Be sure the high pressure bleed

surfaces with a magnifying glass. The slightest imper-

hole in side of bushing is not plugged. If this hole is

fections will prevent the injector from operating prop-

plugged fuel leakage will occur at upper end of bushing

erly. Check for burrs, nicks, erosion, cracks, chipping

where it will drain out of injector body vent and rack

and excessive wear. Check for enlarged orifices in

holes, during engine operation, causing a serious oil

spray tip. Replace damaged or excessively worn parts.

dilution problem. Keep plunger and bushing together

as they are mated parts.

(j) Examine needle valve for wear, scoring or

(n) After washing, submerge parts in a clean re-

damage to grill where it contacts the valve spring seat.

ceptacle containing clean fuel oil. Keep parts of each

If the needle valve is scored or damaged, replace the

spray tip assembly.

injector assembly together.

(2) Inspection.

(k) Before installing used injector parts, lap all

(a) Inspect teeth on control rack and control

sealing surfaces. It is also good practice to lightly lap

rack gear for excessive wear or damage. Also, check

sealing surfaces of new injector parts which may be-

for excessive wear in bore of gear, replace damaged or

come burred or nicked during handling.

worn parts.

f. Lapping Injector Parts. Lap sealing surfaces in-

(b) Inspect injector follower. for wear. Inspect

dicated in figure 3-49 as follows:

both ends of spill deflector for sharp edges or burrs

(1) Clean lapping blocks with compressed air. Do

which could create burrs on injector body or injector

not use a cloth or any other material for this purpose.

nut and cause particles of metal to be introduced into

(2) Spread a good quality 600 grit dry lapping

powder on one of the lapping blocks.

the spray tip and valve parts. Remove burrs with a 500

grit stone.

(3) Place part to be lapped flat on block and using

(c) Inspect follower spring for defects and check

a figure eight motion, move it back and forth across

the block. Do not press on the part, use just enough

spring with a spring tester and a torque wrench. The

injector follower spring (O.142-inch diameter wire) has

pressure to keep part flat on the block at all times.

a free length of approximately 1.504 inches and must

(4) After each four or five passes, clean lapping

be replaced when a load of less than 70 pounds will

powder from part by drawing it across a clean piece of

tissue placed on a flat surface and inspect the part. Do

compress it to 1.028 inches.

(d) Check seal ring area on injector body for

not lap excessively.

burrs or scratches. Also check surface which contacts

(5) When the part is flat, wash it in cleaning sol-

injector bushing for scratches, scuff marks or other

vent (Fed Spec PD-680) and dry with compressed air.

damage. If necessary lap this surface. A faulty sealing

(6) Place dry part on the second lapping block.

surface at this point will result in high fuel consump-

After applying lapping powder, move part lightly

tion and contamination of the lubricating oil.

across block in a figure eight motion several times to

(e) Replace any loose injector body plugs or a

give it a smooth finish. Do not. lap excessively. Again

loose dowel pin. Install proper number tag on a re-

wash part in cleaning solvent (Fed Spec PD-680) and

placement injector.

dry with compressed air.

3-30