ENGINE DIAGNOSTIC TEST PROCEDURES Section 6 • TEST INJECTION NOZZLES (Continued) 2. Injection Nozzle Testing The   prime   requirements   for   a   satisfactory   nozzle assembly  are:    pressure  tight  seats;  no  excessive valve stem leakage; satisfactory spray and automization characteristics. a. After   removal   from   engine,   test   nozzles   for spray  condition,  opening  pressure  and  leakage on a hand test pump SE-2002. Figure  24  shows  an  injection  nozzle  mounted for testing on the hand test pump. IMPORTANT IT     IS     ADVISABLE     TO     TEST     NOZZLES BEFORE CLEANING THEM. AFTER TESTING PLACE NOZZLES IN A COLD DECARBONIZING SOLUTION FOR AT LEAST ONE   HOUR.   AFTER   REMOVING   NOZZLES FROM SOLUTION, WASH OFF THE OUTSIDE SURFACES. b. Prepare   pump   for   making   tests.      Fill   pump reservoir   with   Viscor   1487C   calibration   fluid. Open   pump   valve   slightly   and   operate   pump handle  to  expel  air  from  pump  and  outlet  pipe. Operate    pump    until    solid    fluid    (without    air bubbles)  flows  from  end  of  outlet  pipe.    Close pump valve. c. Connect  injection  nozzle  to  test  pump.    Avoid "cross-threading". Tighten connector nut securely with open end wrench. d. Bleed  air  from  nozzle.    Open  pump  valve  and operate pump for several quick strokes to expel (bleed)  air  from  injection  nozzle.    Fluid  should spray from the spray holes in nozzle tip. Figure 24.  Typical Nozzle Assembly Mounted in the Hand Test Pump 1. Pressure Gauge 2. Nozzle Tube Assembly (SE-2004-13) 3. 90 Adapter (SE-2757) 4. Nozzle Assemblies IMPORTANT KEEP HANDS AWAY FROM NOZZLE SPRAY. FLUID     SPRAYING     FROM     THE     NOZZLE UNDER  HIGH  PRESSURE  CAN  PENETRATE THE SKIN AND CAUSE INFECTION. MEDICAL ATTENTION SHOULD BE PROVIDED IMMEDIATELY IN THE EVENT OF SKIN PENETRATION. e. OBSERVE   SPRAY   PATTERN.      Operate   test pump   in   smooth,   even   strokes   and   observe pattern  of  fluid  spraying  from  nozzle  tip  spray holes.  The spray should be well atomized in an even    pattern,    free    from    solid    streams    and dribbling.      Examples   of   good   and   bad   spray patterns are shown in Figure 25. f. CHECK NOZZLE OPENING PRESSURE. Open  gauge  valve,  operate  test  pomp  in  slow smooth,    even    strokes    and    observe    gauge pressure to determine pressure at which nozzle opens   (sprays   fluid).      Nozzle   should   operate within specified opening pressure range. CGES-240-4 Printed in United States of America Page 34