ENGINE DIAGNOSTIC TEST PROCEDURESSection 6•TEST INJECTION NOZZLES (Continued)2.Injection Nozzle TestingThe prime requirements for a satisfactory nozzleassembly are: pressure tight seats; no excessivevalve stem leakage; satisfactory spray andautomization characteristics.a.After removal from engine, test nozzles forspray condition, opening pressure and leakageon a hand test pump SE-2002.Figure 24 shows an injection nozzle mountedfor testing on the hand test pump.IMPORTANTIT IS ADVISABLE TO TEST NOZZLESBEFORE CLEANING THEM. AFTER TESTINGPLACE NOZZLES IN A COLDDECARBONIZING SOLUTION FOR AT LEASTONE HOUR. AFTER REMOVING NOZZLESFROM SOLUTION, WASH OFF THE OUTSIDESURFACES.b.Prepare pump for making tests. Fill pumpreservoir with Viscor 1487C calibration fluid.Open pump valve slightly and operate pumphandle to expel air from pump and outlet pipe.Operate pump until solid fluid (without airbubbles) flows from end of outlet pipe. Closepump valve.c.Connect injection nozzle to test pump. Avoid"cross-threading". Tighten connector nutsecurely with open end wrench.d.Bleed air from nozzle. Open pump valve andoperate pump for several quick strokes to expel(bleed) air from injection nozzle. Fluid shouldspray from the spray holes in nozzle tip.Figure 24. Typical Nozzle Assembly Mountedin the Hand Test Pump1.Pressure Gauge2.Nozzle Tube Assembly (SE-2004-13)3.90 Adapter (SE-2757)4.Nozzle AssembliesIMPORTANTKEEP HANDS AWAY FROM NOZZLE SPRAY.FLUID SPRAYING FROM THE NOZZLEUNDER HIGH PRESSURE CAN PENETRATETHE SKIN AND CAUSE INFECTION.MEDICAL ATTENTION SHOULD BEPROVIDED IMMEDIATELY IN THE EVENT OFSKIN PENETRATION.e.OBSERVE SPRAY PATTERN. Operate testpump in smooth, even strokes and observepattern of fluid spraying from nozzle tip sprayholes. The spray should be well atomized in aneven pattern, free from solid streams anddribbling. Examples of good and bad spraypatterns are shown in Figure 25.f.CHECK NOZZLE OPENING PRESSURE.Open gauge valve, operate test pomp in slowsmooth, even strokes and observe gaugepressure to determine pressure at which nozzleopens (sprays fluid). Nozzle should operatewithin specified opening pressure range.CGES-240-4Printed in United States of AmericaPage 34
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