TM 5-3895-346-14
FUEL INJECTOR
ENGINE OVERHAUL
NOTE
Keep the parts of each injector assembly together.
Inspect Injector Parts
Inspect the teeth on the control rack and the control rack gear for excessive wear or damage. Also check for
excessive wear in the bore of the gear and inspect the gear retainer. Replace damaged or worn parts.
Inspect the injector follower and pin for wear. Refer to Specifications and Troubleshooting.
Inspect both ends of the spill deflector for sharp edges or burrs which could create burrs on the injector body or
injector nut and cause particles of metal to be introduced into the spray tip and valve parts. Remove burrs with
a 500-grit stone.
Inspect the follower spring for visual defects. Then check the spring with spring tester J 22738-02.
The current injector follower spring (0.142-inch-diameter wire) has a free length of approximately 1.504 inches
and should be replaced when a load of less than 70 lbs. will compress it to 1.028 inches.
It is recommended that at the time of overhaul, all injectors in an engine be converted to the current spring
(0.142-inch-diameter wire) which will provide improved cam roller-to-shaft follow. However, in the event that
one or two injectors are changed, the remaining injectors need not be reworked to incorporate the current
spring.
Check the seal ring area on the injector body for burrs or scratches. Also check the surface which contacts the
injector bushing for scratches, scuff marks or other damage. If necessary, lap this surface. A faulty sealing
surface at this point will result in high fuel consumption and contamination of the lubricating oil. Replace any
loose injector body plugs or a loose dowel pin. Install the proper number tag on a service replacement injector
body.
Inspect the injector plunger and bush- ing for scoring, erosion, chipping, or wear. Check for sharp edges on
that portion of the plunger which rides in the gear. Remove any sharp edges with a 500-grit stone. Wash the
plunger after stoning it. Injector bushing inspectalite J 21471 can be used to check the port holes in the inner
diameter of the bushing for cracks or chipping. Slip the plunger into the bushing and check for free movement.
NOTE
Replace the plunger and bush- ing as an assembly if any of the above damage is noted, since
they are mated parts.
Use new mated factory parts to assure the best performance from the injector.
Injector plungers cannot be reworked to change the output. Grinding will destroy the hardened case at the helix
and result in chipping and seizure or scoring of the plunger.
Examine the spray tip seating surface of the injector nut and spray tip for nicks, burrs, erosion, or brinelling.
Reseat the surface or replace the nut or tip if it is severely damaged.
The injector valve spring plays an important part in establishing the valve opening pressure of the injector as-
sembly. Replace a worn or broken spring.
Inspect the sealing surfaces of the in- jector parts indicated by arrows in Fig. 31. Examine the sealing surfaces
with a magnifying glass as shown in
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