TM 10-3930-671-24 3. Loosen any two injector high-pressure pipe nuts at  the  injector  end.    Set  the  accelerator  to  the fully-open position.  Crank engine until clean fuel (free of air) flows.  Tighten nuts. 4. Check Operation a) Energize the glow plugs. b) Start the engine. Fuel Filters Clark  diesels  are  normally  equipped  with  the  fuel  filter installed  between  the  transfer  pump  outlet  and  the  fuel injection  pump,  thus  placing  the  filter  on  the  pressure side of the transfer pump. The PM interval for changing the filter element will largely depend    upon    the    quality    and    condition    of    the    fuel available.  Under normal conditions,  the  element  should be  replaced  every  400  hours.    This  interval  should  be reduced    if    incidental    contamination    of    the    fuel    is experienced. NOTE • Clean  fuel  Is  a  must  In  diesel  operation. When    clean    fuel    Is    not    consistently available, additional filters may be required for reliable engine operation. • Electrical   equipment,   such   as   starters, should be protected against fuel damage during filter replacement and priming. Fuel Filter Replacement The   fuel   filter   is   a   paper-element   type.      No   attempt should   be   made   to   clean   the   element.      It   should   be replaced when periodic maintenance is being carried out. 1. Remove filter bowl. 2. Discard the dirty element.  Remove and discard the  upper  and  lower  element  sealing   washers and O-ring from the center stud. 3. Clean the inside of the bowl and center tube. 4. Fit  the  new  upper  and  lower  sealing  washers. Install new O-ring on the center stud.  Place the new filter element in position and install the bowl. Tighten center stud. 5.    Vent  (bleed)  the  fuel  system  (refer  to  Section  5.3, Priming the Fuel System). 6.    Fuel Injectors Injectors   should   be   removed   (taken   out)   only   if   the engine is malfunctioning, as follows: 1) Misfiring. 2) Knocking in one or more cylinders. 3) Engine overheating. 4) Loss of power. 5) Smoky exhaust (black or white). 6) Increased or excessive fuel consumption. WARNING Do not use your hands to check for fuel leakage. Use a piece of cardboard or paper to search for leaks.        Escaping    fluid    under    pressure    can penetrate    the    skin    causing    serious    Injury. Relieve pressure before disconnecting fuel lines. Tighten all connections before applying pressure.      Keep   hands   and   body   away   from pinholes  and  nozzles  which  elect  fluids  under high  pressure.    If  Injured  by  escaping  fluid,  get medical attention at once.  If any fluid Is injected into   the   skin,   it   must   be   surgically   removed within a few hours by a doctor familiar with this type injury or gangrene may result. 1. When  installing  injectors  in  the  engine  cylinder head it is essential that a new, correct type heat shield  washer  be  fitted  between  the  nozzle  cap and the cylinder head. 2. Tighten  injectors   evenly   to   52   lb   ft   [71   N•m] torque. F-204