TM 10-4320-307-244-11INJECTORREPAIRCONT).9.Inspect injector cup by comparing with new cup. Discard cup if any of the following conditions exist:a.Abrasive wear: This wear can begin internally, therefore both interior and exterior surfaces must beinspected.b.Corrosion and erosion damage and the effect of excessive heat: This condition usually results from highwater, acid or sulphur content in the fuel or from overloaded operating conditions. Slight erosion on outsideof cup which has not changed hole size can be tolerated. In cases of major damage, replace cup.c.Enlarged or distorted spray holes caused either by high operating hours or by improper cleaning techniquessuch as wire brushing or cleaning holes with drill bit.NOTEThe plunger must seat in the cup from 1/4 of the upper cone area to the full conearea. Reject a cup that seats in lower 1/4 cup tip area. If a cup seats in the tiparea, it must seat more than 1/2 of cone area to be accepted.d.Bad seating pattern of plunger to cup: In-spect cup (2) for plunger seat pattern. Selecta new plunger and coat tip with prussianblue. Insert plunger in cup and rotate 90 de-grees. If plunger seat covers a 40 percentcontinuous area around cup cone or plungerbore, it is possible the cup may be reused.The cup must also pass cup-to-plunger leaktest.e.Mutilation and flatness of injector cup barrelseating surface:(1) Visually inspect area shown blackenedin figure for mutilation.(2) Use a flat steel plate (preferably a lap-ping plate) and bluing to check for sur-face flatness.(3) If mutilation or unevenness is found, re-pair or replace barrel.10.Inspect injector adapter as follows:a.Check balance orifice for burrs or other ob-structions.b. Inspect both fuel passages to be certain theyare open.c.Inspect cup retainer threads for damage.d.Check O-ring areas for nicks or burrs whichwill damage O-rings during installation.e.Inspect barrel mating surface for nicks orburrs. If damage is found, lap to repair.f.Check inside diameter behind adjustable ori-fice plug. If a burnishing needle that is toolong is used, there will be a hole through theadapter. This will cause lubricating oil dilu-tion.4-84
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