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
(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.
(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.
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
(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
dry with compressed air.