ENGINE DIVISION SERVICE MANUAL TM 5-4210-230-14&P-1 ENGINE Oil Pan The  pan  should  be  thoroughly  cleaned  in  cleaning solvent to remove any foreign material from around the baffle plate which is spot welded in place.  Inspect oil pan for cracks or deformation and straighten or weld. Remove all gasket material from the oil pan flange. Check  the  oil  pan  drain  plug  boss  for  fit  and  thread wear.  If the plug is loose or the threads are damaged, repair the threads or replace the oil pan. Manifolds The intake manifold is cast in one piece and supplies both  cylinder  banks.  It  should  be  cleaned  and  examined  for cracks or leaks.  Warpage of the intake manifold will require replacement  as  any  attempt  to  resurface  the  intake  manifold will  create  misalignment  of  the  ports  to  the  cylinder  heads. The  intake  manifold  also  contains  the  direction  of  distributor rotation, firing order and the cylinder numbers Figure 135. Fig. 135 Illustration of Information Contained on Intake Manifold 1.  Cylinder number 2.  Direction of distributor rotation 3.  Firing order Each  bank  has  a  separate  exhaust  manifold  which should both be cleaned and examined for cracks or leaks. Flywheel and Ring Gear Clean   the   flywheel   and   ring   gear   with   a   cleaning solvent,  removing  all  traces  of  oil  and  grease.    Inspect  the flywheel  ring  gear.    If  any  teeth  are  damaged  or  if  the  ring gear is loose on the flywheel, the ring gear must be replaced.  Check the flywheel mounting bolt holes   for   wear;   also   check   mounting   face   of   flywheel   for indication of looseness. To replace the flywheel ring gear, heat the gear with a  torch  and  remove  it  from  the  flywheel  with  a'  hammer  and drift Heat the new ring gear evenly all the way around with a torch.      While   the   ring   gear   is   hot,   install   the   gear   on   the flywheel and allow it to cool. Water Pump and Coolant Flow Coolant   enters   the   engine   at   the   lower   left   hand corner of the crankcase. The coolant then flows into the water pump   where   it   is   mixed   with   a   quantity   of   bypassed   hot coolant.    The  water  pump  discharges  into  both  the  right  and left  of  the  crankcase.    The  circulation  of  the  coolant  is  from front to rear of the crankcase, then flows up into the cylinder head via three holes.  The flow continues forward through the cylinder head. In flowing through the cylinder head the coolant is forced through a zig-zag path to insure maximum scrubbing of  critical  areas  of  the  cylinder  head  such  as  exhaust  valve seats and spark plugs. The coolant exits the cylinder heads into a common cavity at the front of the crankcase.  Temperature sending unit is  located  in  this  cavity.    From  this  cavity  the  coolant  flows into  the  chassis  radiator  or  back  into  the  water  pump  via  a variable orifice bypass.  The amount of Fig. 136 Coolant Flow Cut-Away 1.  Full pressure flow to rear of crankcase-up-and to front of lead. 2.  Outlet 3.  Bypass 4.  Inlet CGES-210  Page 55 PRINTED IN UNITED STATES OF AMERICA