TM 5-3810-295-34
f
Remove spill deflector (18) and seal ring (19) from the injector nut.
g
Remove bushing (20), gear retainer (21), gear (22), and rack (23) from the injector body.
h.
Withdraw dowel (24) from injector body (25).
3-64. Inspection and Repair
Clean all parts in cleaning solvent, Federal Specification P-D-680, or equivalent, before inspection.
NOTE
Since most injector difficulties are the result of dirt particles, it is essential that a clean area be provided on which to place
injector parts after cleaning and inspection. Do not use waste or rags for cleaning purposes.
b. Be sure all passages, drilled holes and slots are clean.
c
Discard filteir, seals and gaskets.
CAUTION
Care must be taken not to ream spray tip oversized.
d
Clean spray tip (10) with a suitable reamer to remove carbon deposits. Clean spray tip orifices with a suitable
cleaning wire. Before using the wire, hone the end of the wire to remove all sharp edges and burrs. Taper the end of the
wire a distance of one-sixteenth of an inch.
e. The exterior surface of the spray tip may be cleaned with a brass wire buffing wheel.
NOTE
When handling the injector plunger, do not touch the finished plunger surfaces with your fingers. Wash the plunger and
bushing with clean fuel oil and dry them with compressed air.
f
Be sure the high pressure bleed hole in the side of the bushing is not plugged. If the hole is plugged, fuel
leakage will occur at the upper end of the bushing, where it will drain from the injector rack and vent holes, and can cause
serious lubrication dilution problems.
NOTE
Keep the plunger and bushing together because they are mated parts. Replace only as a set.
g
Inspect the teeth on the control rack and the control rack gear for excessive wear and damage. Also check for
wear and damage in the bore of the gear and inspect the gear retainer. Replace worn or damaged parts.
h. Clean and brush all passages in the injector body. Blow out passages with compressed air.
I
Carefully ream the injector nut, being careful not to remove metal or set up burrs.
j.
Carefully ream the injector body. After a few turns, remove the reamer and check the face of the ring bore for
reamer contact over the entire face of the ring. Repeat reaming if necessary. Clean the opposite end of the ring in the
same manner.
k. Inspect the injector follower and pins for wear.
l
Inspect both ends of the spill defector for sharp edges or burrs that could create burrs on the injector body or
nut and cause particles of metal to be carried into the spray tip and valve parts. Remove burrs with a 500 grit stone.
m. Inspect the follower spring for defects.
n. Check the seal ring areas on the injector body for burrs or scratches. Check the surface which contacts the
injector bushing for scratches, scuff marks or other damage. If necessary, lap this surface.
o. Inspect the injector plunger and bushing for scoring, erosion, chipping or wear. Check for sharp edges on that
portion of the plunger that rides in the gear. Remove any sharp edges with a 500 grit stone. Wash the injector after it
has been stoned. Slip the plunger into the bushing and check for free movement. Replace bushing and plunger as an
assembly if any of the above damage is noted.
p. Examine the spray tip seating surface of the injector nut for nicks, burrs or brinelling. Reseat the surface or
replace the nut if it is severely damaged.
q. The injector valve spring is important in establishing the valve opening pressure. Replace a worn or damaged
spring.
r.
Inspect the sealing surfaces of the spray tip and valve parts. Examine the sealing surfaces with a magnifying
glass for even the slightest imperfections. Check for burrs, nicks, cracks, chipping and excessive wear. Also check for
enlarged orifices in the spray tip. Replace damaged or excessively worn parts.
s
Before reinstalling used valve parts ih an injector, lap all of the sealing surfaces indicated below. After
lapping, minimum thicknesses should be as follows:
Spray tip (shoulder)
0.121 inch
Injector valve
0.073 inch
Valve cage
0.490 inch
Valve seat
0.124 inch
Check valve
0.027 inch
t
After lapping is complete, clean all lapped parts in clean fuel oil and blow dry with compressed air.
3-65. Reassembly
a. Refer to figure 3-14. Hold the injector body right side up and place a new filter (4), slot side up, in each of the
fuel cavities. Install springs (3) and gaskets (2). Lubricate the threads and install caps (1), tightening the caps to 65--75 ft-
lb (8--102 N m).
b. Purge the filters with compressed air blown through the filter caps. Install clean shipping cap? On the filter
caps to prevent dirt or foreign material from entering the fuel cavities.
c. Hold the injector body, bottom end up, and slide rack (23) through the hole in the body. Look into the bore for
the rack teeth. Then move the rack until the
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