TM 1-1500-204-23-1 (d) Place   filter   on   a   25-degree   angle draining   rack   in   a   room   where   temperature   is   70 °F (21°C)   and   allow   to   drain   for   2   to   4   hours.      Drain accordion-pleated filters for 8 hours. (e) When necessary, use forced draining  after  gravity  draining  has  been  accomplished by using a 1/16-inch orifice and 100 psi air temperature. (5) Adjust     carburetor     air     doors     so     they operate freely through full range of travel or to position selected as specified in applicable maintenance manual. (6) Replace  damaged  intake  pipes.    Detect leaks   in   Intake   pipes   by   presence   of   fuel   stains   at cylinder  Impeller  end  When  leakage  is  found  after  25 hours   of   operation   (since   new),   loosen   intake   pipe packing   nuts.      Replace   any   defective   packing   and retighten nuts. NOTE Do  not  tighten  packing  nuts  without loosening and examining the packing first. b. Turbocharger   and   Supercharger   Maintenance. Visual     inspection     of     all     visible     parts     should     be accomplished daily to observe oil leaks, exhaust leaks, cracks  in  the  metal  of  hot  sections,  loose  or  insecure units,  and  other  unacceptable  conditions.    Refer  to  the applicable maintenance manual for specific maintenance  procedures.    Ensure  the  following  Items are checked. ·    Mounting of all units ·    Oil leaks or dripping from any unit ·    Security of oil lines ·    Security and condition of electric wiring ·    Cracks in ducting and other metal parts including the turbine and housing ·    Warping of metal ducts ·    Operation    of    the    complete    system    to determine performance to discover undesirable  sounds,  and  to  note  evidence  of vibration;    unusual    sounds    and    appreciable vibration require removal and replacement of the turbocharger to correct the faulty condition NOTE Exhaust  ducts,  waste  gates,  nozzle boxes, and turbines are subjected to extremely   high   temperatures.      For this  reason,  cracks  develop  because of    the    continued    expansion    and contraction of the metal as temperature changes occur. 7-8.    Exhaust  System.    The  exhaust  system  conducts exhaust  gases  from  the  engine  to  the  atmosphere  with minimum exhaust back pressure.  Short exhaust stacks are  incorporated  on  some  engines,  while  others  join  a collector ring which expels exhaust gases through a tail pipe.        Perform    the    following    general    maintenance procedures on exhaust systems: a. Check   ball   joints   for   excessive   or   insufficient clearances,    and    retighten    or    replace    ball    joints    as necessary to obtain free movement. b. Replace all parts that have hot spots or damage beyond repair. c. To prevent exhaust port studs from seizing, and to retard corrosion, apply a special lubricant as follows: (1) When  engine  or  cylinder  is  removed  or installed, apply light coating of 10 percent molybdenum disulphide     lubricant,     MIL-M-7866,     and     90     percent grease, MIL-G-3545, to threads of cylinder exhaust port studs. (2) To   retard   corrosion   of   nuts,   apply   this mixture to exterior of exhaust port stud nuts. d. Tighten  all  nuts,  bolts,  and  clamps  in  exhaust system   in   accordance   with   maintenance   manual   for engine involved. 7-9.  Carburetion and Fuel Injection.  Fuel is metered to the engine at a predetermined ratio to airflow by the fuel  metering  system.    Fuel  metering  systems  differ  in design, but their function is the same, regardless of type or   engine   model.      Improper   maintenance   of   the   fuel metering system will result in rough engine performance,  detonation,  spark  plug  fouling,  low  power output, poor acceleration, and engine or part failure. a. Inspection.      Inspect   carburetors   for   mounting flange cracks and evidence of leakage and fuel strainers for    foreign    matter    broken    screens,    corrosion,    and distortion. 7-36