TM 10-3930-671-24 Preliminary Checks For safety when checking or removing battery connections,    always    disconnect    the    negative    battery cable at the engine ground connection first. Be   careful   when   inspecting   or   replacing   the   air   filter element   to   prevent   dirt   from   entering   the   engine   air intake housing. Damage to engine may result. NOTE The   following   quick,   simple   checks   should   always   be made to make sure that basic and easy  to  find  troubles are not the cause of poor engine performance. Once you have eliminated these items you can check into the other possible causes of poor engine performance. The  following  preliminary  tests  show  whether  the  basic engine  systems  are  functioning  and  that  charging  and cranking systems are okay or in need of repair. Remove the voltmeter after these tests are made. Blow-by,     circulated     into     intake     manifold,     maintains crankcase pressure within a narrow range regardless of operating speed or load. Servicing of the PCV system is usually   confined   to   cleaning   PCV   orifice   and/or   valve along  with  cleaning  the  air  inlet,  where  applicable.  All connections must be air tight. 1. Check engine oil and coolant levels. 2. Check engine air filter. A clogged filter will cause engine power loss. Replace, as needed. 3. Check air intake tubes for signs of filter leakage. 4. Check crankcase breather system to be sure it is functioning correctly. Check the following  and,  if necessary, clean or replace faulty parts. a) Breather  hoses  for  damage,  cracks,  and clogging. b) Rocker   cover   and   intake   manifold   fitting holes for clogging. c) Repair or replace as required. 5. Check   battery   for   damage   and   cleanliness   of terminals.  Remove  the  boot  covers  to   expose terminal   connections.   Clean   battery   terminals and   cable   connections   if   they   are   dirty   and corroded. Check battery terminal cable connections   for   tightness.   Replace   boots   over terminals   after   inspection.   If   necessary,   wash battery  with  a  mild  solution  of  baking  soda  and water.  First,  make  sure  that  cell  vent  caps  are tight    to    ensure    that    soda    solution    does    not contaminate battery electrolyte. F-74