TM 10-3930-671-24 CAUTION When Installing camshaft, use special care   to   prevent   camshaft   bumping and loosening expansion plug at rear of crankcase causing an oil leak. 1. Inspect   each   tappet   carefully.      Two   or   three small   pits   on   the   contact   face   is   acceptable; more   than   that   calls   for   replacement   of   the tappet.  A damaged tappet could mean possible damage to the camshaft. 2. Check the outside diameter with a micrometer to determine  if  replacement  is  necessary  because of wear.  Refer to limits and clearance section. REAR CRANKSHAFT OIL SEALS The overhead valve engines have the rear crankshaft oil seals incorporated in the combination rear main bearing cap and filler block. The rear crankshaft oil seal has a stiffener ring imbedded in the rubber and no metal retainer is required. The  overhead  valve  engines  have  a  good,  trouble-free rear crankshaft oil seal if carefully installed. IMPORTANT:        Installing    rear    oil    seals    correctly demands  careful  workmanship.    Install  seal  with  lip pointing toward engine. Worn   oil   seals   should   be   replaced   in   the   following manner: 1. Remove    rear    bearing    cap     and     filler     block assembly by using a puller. Remove   old   seals   and   thoroughly    clean    all    contact surfaces. 2. Install  crankshaft  oil  seals  "A"  on  engine  block and main bearing cap. Before installing break edge ’C" slightly on both cap and block  to  avoid  cutting  the  seals  during  installation  and coat  seal  edge  ’E",  contacting  the  groove  with  sealing compound. NOTE This  oil  seal  can  be  Installed  without removing the crankshaft in this case, use    only    light    grease    in    the    seal groove   to   assist   sliding   the   seal   in place.    Apply  pressure  to  the  seal  so that  it  will  hug  the  crankshaft  which will also help moving it In place. F-181