TM 1-1500-204-23-1 NOTE Engines  need  not  be  preoiled  after oil     change     or     after     oil     system components have been disconnected for   normal   maintenance.      However, after oil change or after disconnecting oil system components   located   in   the   system between    oil    tank    and    engine    oil pump, it will be necessary to disconnect  oil  inlet  line  at  the  pump and  drain  a  sufficient  amount  of  oil from the line to determine there is no obstruction or air in the system. (1)  Prepare engine for preoiling as follows: (a)    Service  oil  tank,  oil  sump,  or  crankcase  with engine oil specified In applicable maintenance manual. (b)  Provide an external power source. (c)      When    spark    plugs    have    been    installed, remove  one  spark  plug  from  each  cylinder  to  reduce load on starter. (d)    Place  engine  controls  in  following  positions, as applicable. Ignition switch .......................................OFF Throttle .............................................. OPEN Mixture control .....................IDLE CUT-OFF Fuel shutoff valve .................................OFF Oil shutoff valve................................. OPEN (e)  Provide suitable containers of approximately 5 gallons   capacity   to   catch   oil   that   drains   from   sumps during preoiling operation. (f)   On  engines  which  utilize  crankcase  breathers and   which   are   equipped   with   a   hydromatic   propeller, remove plug from propeller dome and pour a sufficient amount of preoiling lubricant into dome to bring lubricant level   to   plug   hole.      Reinstall   and   safety   the   plug   In propeller dome. NOTE This step is not required for engines having     propeller     shaft     breathers, reversible-type propellers, or engines not equipped with hydromatic propellers. (2)  Preoil engine by one of the following methods: CAUTION Devices  having  heating  elements  in direct  contact  with  preoiling  mixture or oil shall not be used Damage may otherwise result (a)      Preoil   engine   having   a   dry   sump-type   oil system using a pressure tank. (b)    Preoil  engine  having  a  wet  sump  by  rotating crankshaft  with  starter  and  utilizing  normal  engine  oil supply and oil pump to provide pressure (3)        Provide    suitable    viscosity    by    heating    and maintaining lubricant used for preoiling at a temperature between   110   to   175°F   (38 °   to   80°C)   when   using preoiling equipment incorporating provisions for heating. When preoiling with engine oil pump or with equipment not incorporating a heating element, dilute lubricant, at a temperature   lower   than   30 °F   (-1 °C),   with   gasoline   in accordance    with    percentage    calculated    from    chart shown In figure 7-25.  Mix thoroughly prior to preoiling. (4)   Preoil O-series engines by servicing oil system with  grade  oil  specified  for  engine,  and  the  turn  engine through   with   starter   until   oil   pressure   is   indicated   on aircraft oil pressure gauge. (5)  Preoil all radial engines as follows: CAUTION Do    not    energize    starter    over    15 seconds.    Allow  starter  to  cool  after each  energizing.    Damage  to  starter may otherwise result (a)    Prime  oil  pump  by  removing  applicable  plug and    rotating    crankshaft    with    starter    until    all    air    is expelled  from  vent  and  a  steady  flow  of  oil  is  coming from vent.  Reinstall plug. NOTE On    engines    not    having    a    plug, disconnect   oil   inlet   line   and   allow sufficient oil to drain to assure air in the line is eliminated. (b)      Remove   drain   plugs   from   front   and   rear sumps on installations having sumps in these locations. 7-45