TM 10-4320-307-244-11INJECTORREPAIR(CONT).b.Check closely for metal seizure. This is the only true indication of scuffing or scoring.c.Bright spots or surface disruption at top of plunger machined area, on the opposite side at the bottom ofplunger, or at mid-point, usually are normal results of rocker lever thrust action. Unless metal is displaced orwear is measurable at these points, the plunger can be reused. If barrel and plunger do not pass a leakagetest a new barrel and plunger assembly must be installed.d.Narrow streaks running the length of the plunger usually are the result of varying thicknesses of penetranttreatment used to prevent rusting. The plunger may be reused unless surface disruption in metal is evident.e.Carbon deposits on the small diameter near tip of plunger may be caused by injector timing being set tooslow.NOTEThis condition, if present, will have been observed and noted before cleaning.7.Inspect injector barrel as follows:a. Inspect injector barrel plunger bore for scoring or corrosion. If injector will pass leakage test, the barrel isusable. If leakage is too high, barrel and plunger must be replaced.b.Use a strong magnifying glass to check for burrs, carbon, and distorted radii in the orifice. When meteringorifice is damaged, the injector will not function properly. Do not attempt cleaning with wires, plug gauges,etc. Use solvent cleaners.c.Check fuel passage plugs for looseness and the barrel for cracks.d.Check injector barrel surfaces for mutilation.8.Inspect check ball and barrel check ball seat as follows:a.Replace check ball if worn or damaged.b.Inspect check ball seat for damage.c.If damage is found, the check ball seat can be improved by lapping a ball to the seat as follows:(1) Weld check ball to end of a small rod.(2) Use 600 grade paste lapping compound to lap the seat.(3) Clean lapping compound out of barrel.d.Inspect depth of check ball seat.(1) Install check ball in barrel.(2) Using depth micrometer, check that depth of ball does not exceed 0.055 inch (1.40 mm). If it does,barrel and plunger must be replaced.e.Perform leakage test to determine if check ball and check ball seat form an adequate seal. Replace barreland ball if leakage exceeds recommended limits.4-83
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