a. Frequency   and   voltage   regulation,   stability, and–transient   response   test,   short   term.   Refer   to paragraph    16-15. b.   Frequency   adjustment   range   test.   Refer   to paragraph    16-16. Section  IX. TURBOCHARGER 14-51.   General. a.   The   turbocharger   is   an   exhaust   driven   blower used  to  boost  the  power  output  of  an  engine  over  that of  a  naturally  aspirated  engine  by  increasing  the  sup- ply   of   air   to   the   cylinders.   The   turbocharger   incor- porates   a   single   stage   radial   inflow   turbine   wheel, mounted  on  a  common  shaft  with  a  single  stage  cen- trifugal   compressor   impeller.   It   has   a   one-piece center   housing   with   floating   sleever   type   bearings, a  turbine  housing,  and  a  compressor  housing. b.   The   turbocharger   responds   to   engine   load demands  by  reacting  to  the  flow  of  expanding  exhuast gases  and  supplying  a  correlated  volume  of  air  to  the engine   cylinders. During  a  heavy  load/lugging operation,   the   increased   flow   of   exhaust   gases   turns the   turbine   wheel   faster,   causing   the   compressor impeller  to  turn  faster  to  supply  more  air  to  the  in- take   manifold,   Conversely,   when   engine   load   is   light and  the  radial  flow  of  gases  within  the  turbine  de- creases,   the   turbocharger   compressor   reduces   the supply  of  air  to  the  intake  manifold. c.  The  turbocharger  bearings  are  lubricated  and cooled  by  filtered  engine  oil  circulating  through  the center   housing   under   normal   oil   pump   pressure.   This oil  is supplied  to  the  center  housing  through  an  ex- ternal   line   through   the   engine   main   oil   filter.   Oil returns   to   the   crankcase   through   an   external   line which  extends  from  the  bearing  housing  to  the  side  of the  cylinder  block. d.  The  turbine  of  the  turbocharger  is  part  of  the exhaust    system. The  exhaust  manifold  on  a  turbo- charged  engine  is  in  three  sections  with  the  front  and the   rear   sections   inserted   into   the   center   section. The  manifold  is  sealed  to  the  exhaust  parts  of  the cylinder  head  with  a  steel  gasket  and  secured  in place   with   capscrews   and   lock   washers. 14-52.  Turbocharger  Removal  and  Disassembly. CAUTION While   turbocharger   is   off   engine,   keep all  manifold  openings  covered  to  prevent entry  of  foreign  objects. a.   Refer   to   Operator   arid   Organizational   Mainte- nance  Manual  for  symptoms  and  isolation  of  malfunc- tion  of  the  turbocharger. b.   Refer   to   Operator   and   Organizational   Mainte- nance   Manual   and   remove   turbocharger, c.   Disassemble   turbocharger   in   the   numerical sequence   illustrated   in   figure   14-26. CAUTION Do  not  rest  the  center  housing  with  the included   stationary   and   rotating   parts   on the  compressor  impeller.  Weight  of  the complete   assembly   will   damage   the   im- peller   blades. d.   Mark   the   relative   positions   of   the   compressor and-turbine   housings   to   the   center   housing   to   facilitate reassembly. e.   Apply   penetrating   oil,   or   diesel   fuel,   to   the bolts  that  secure  the  turbine  housing  and  backplate to  the  center  housing. f.   Remove   the   compressor   housing.   If   necessary, tap  the  housing  lightly  with  a  soft  hammer  to  loosen it.   Remove   the   diffuser   (3). g.   Record   the   shaft   radial   movement   and   shaft end  play. (1)  Check  shaft  end  play  as  follows:  (Specified end  play  .001”  to  .0042”. (a)  Clamp  the  turbine  housing  flange  in  a vise. (b)  Use  either  a  clamp  or  magnetic  base  dial indicator   .^- (c)  Place  indicator  contact  point  on  end  of impeller   shaft. (d)  Press  up  on  turbine  wheel  to  force  the impeller   to   extreme   up   position;   record   indicator reading. (e)   Press   down   on   impeller;   again   record indicator   leading. (f)  The  difference  between  the  readings  is the  end  play, (g)  End  play  should  be  from  .001”  to  .0042”. (h)  Record  the  end  play,  This  will  be  used to   determine   if   thrust   plate   assembly   or   thrust   bear- ing  need  to  be  replaced. (i)  If  end  play  exceeds  .0042”,  it  indicates 14-57