TM 5-4240-501-14P GENERAL INFORMATION Check-up CHECK - UP Most   complaints   concerning   engine   operation   can   be classified as one or a combination of the following: 1 Will not start 2 Hard starting 3 Kicks back when starting 4 Lack of power 5 Vibration 6 Erratic operation 7 Overheating 8 High oil consumption When  the  cause  of  malfunction  is  not  readily  apparent, perform    a    check    of    the    Compression,    Ignition    and Carburetion   Systems      This   check-up,   performed   in   a systematic  manner,  can  usually  be  done  in  a  matter  of minutesIt     is     the     quickest     and     surest     method     of determining the cause of failure.  This check-up will point up   possible   cause   of   future   failures,   which   can   be corrected at the time.  The basic check-up procedure is the  same  for  all  engine  models,  while  any  variation,  by model will be shown under the subject heading. NOTE:  What  appears  to  be  an  engine  malfunction  may be   a   fault   of   the   powered   equipment   rather   than   the engine        If    equipment    is    suspect,    see    Equipment, affecting engine operation. Check Compression Spin  flywheel  in  reverse  rotation  (counterclock-wise)  to obtain    accurate    compression    check.        The    flywheel should rebound sharply, indicating satisfactory compression. If compression is poor, look for - 1 Loose spark plug 2 Loose cylinder head bolts 3 Blown head gasket 4 Burnt valves and/or seats 5 Insufficient tappet clearance 6 Warped cylinder head 7 Warped valve stems 8 Worn bore and/or rings 9 Broken connecting rod Check Ignition Remove  the  spark  plug.    Spin  the  flywheel  rap-idly  with one end of the ignition cable clipped to the 19051 tester and  with  the  other  end  of  the  tester  grounded  on  the cylinder  head.    If  spark  jumps  the  .166"  tester  gap,  you may assume the ignition system is functioning satisfactorily.  Try a new spark plug. If spark does not occur look for - 1 Incorrect armature air gap 2 Worn bearings and/or shaft on flywheel side 3 Sheared flywheel key 4 Incorrect breaker point gap 5 Dirty or burned breaker points 6 Breaker plunger stuck or worn 7 Shorted ground wire (when so equipped) 8 Shorted stop switch (when so equipped) 9 Condenser failure 10 Armature failure 11 Improperly operating interlock system NOTE:  If  engine  runs  but  misses   during   operation,   a quick  check  to  determine  if  ignition  is  or  is  not  at  fault can be  made  by  inserting  the  19051  tester  between  the ignition  cable  and  the  spark  plug  A  spark  miss  will  be readily  apparent  While  conducting  this  test  on  Magna- Matic  equipped  engines,  Models  9,  14,  19  and  23,  set the tester gap at .060". 1 6