INJECTOR REPAIR CONT).
Inspect injector cup by comparing with new cup. Discard cup if any of the following conditions exist:
Abrasive wear: This wear can begin internally, therefore both interior and exterior surfaces must be
Corrosion and erosion damage and the effect of excessive heat: This condition usually results from high
water, acid or sulphur content in the fuel or from overloaded operating conditions. Slight erosion on outside
of cup which has not changed hole size can be tolerated. In cases of major damage, replace cup.
Enlarged or distorted spray holes caused either by high operating hours or by improper cleaning techniques
such as wire brushing or cleaning holes with drill bit.
The plunger must seat in the cup from 1/4 of the upper cone area to the full cone
area. Reject a cup that seats in lower 1/4 cup tip area. If a cup seats in the tip
area, it must seat more than 1/2 of cone area to be accepted.
Bad seating pattern of plunger to cup: In-
spect cup (2) for plunger seat pattern. Select
a new plunger and coat tip with prussian
blue. Insert plunger in cup and rotate 90 de-
grees. If plunger seat covers a 40 percent
continuous area around cup cone or plunger
bore, it is possible the cup may be reused.
The cup must also pass cup-to-plunger leak
Mutilation and flatness of injector cup barrel
(1) Visually inspect area shown blackened
in figure for mutilation.
(2) Use a flat steel plate (preferably a lap-
ping plate) and bluing to check for sur-
(3) If mutilation or unevenness is found, re-
pair or replace barrel.
Inspect injector adapter as follows:
Check balance orifice for burrs or other ob-
b. Inspect both fuel passages to be certain they
Inspect cup retainer threads for damage.
Check O-ring areas for nicks or burrs which
will damage O-rings during installation.
Inspect barrel mating surface for nicks or
burrs. If damage is found, lap to repair.
Check inside diameter behind adjustable ori-
fice plug. If a burnishing needle that is too
long is used, there will be a hole through the
adapter. This will cause lubricating oil dilu-