ARMY TM 9-2815-256-24 AIR FORCE TO 38G1-96-2 MARINE CORPS TM 2815-24/5 NOTE All locations referenced herein are given facing the flywheel end (rear) of the engine. 1-8.  DETAILED DESCRIPTION. 1-8.1.  Turbocharger.  A turbocharger, operated by exhaust gases, compresses intake air and routes it to the combustion chamber. 1-8.2.   Camshaft.    The  camshaft  is  driven  by  an  intermediate  gear  in  the  timing  gear  train  which  meshes  with  the crankshaft  gear.    Camshaft  rotates  in  honed  machined  bores  in  cylinder  block;  no  bushings  are  used.    The  camshaft lobes determine the time and rate of opening of each valve and actuates the fuel supply pump. 1-8.3.  Intake and Exhaust Valves.  Intake and exhaust valves are operated by cam followers, push rods, and rocker arm assembly.  Valve seat inserts in cylinder head are used for intake and exhaust valves. 1-8.4.   Crankshaft.  The crankshaft is a one-piece, heat treated, steel forging which operates in replaceable two-piece front and center main bearings and five-piece rear main bearing.  The rear thrust bearing has a five-piece set to support crankshaft thrust and to limit end play. 1-8.5.  Cylinder Liners and Pistons.  Cylinder liners are "wet" (surrounded by coolant) and are individually replaceable. O-rings  are  used  to  seal  the  connection  between  cylinder  block  and  liners.    Pistons  are  made  of  cast  high-grade aluminum alloy with internal ribbing.  The skirt is cam ground to allow for expansion when heated during operation.  The piston crown has a cut-out swivel cup with a truncated cone in the center.  Two compression rings and one oil control ring are  used.    The  top  compression  ring  is  a  keystone  type  ring.    All  piston  rings  are  located  above  the  piston  pin.    The hardened piston pins are fully-floating and held in position by means of retainer rings.  Spray jets (piston cooling orifices) in cylinder block direct pressurized oil to lubricate piston pins and cool pistons.  Connecting rods are of forged steel and have replaceable bushing and bearing inserts. 1-8.6.   Cooling  System.    The  cooling  system  consists  of  a  radiator,  water  pump,  cooling  fan,  two  thermostats,  and connecting hoses.  The fan is mounted on shaft of water pump and both are belt driven from the crankshaft pulley.  The thermostats  control  engine  temperature  and  are  installed  in  top  of  engine.    The  function  of  the  cooling  system  is  to maintain a specific operating temperature of 175 to 185°F (79 to 85°C) for the engine. 1-8.7.  Lubrication System.  The lubrication system consists of oil pan (sump), a gear type pump, full flow spin-on oil filter with built-in bypass valve, oil cooler with built-in bypass valve, pressure regulating valve, bypass valve, and the internal passages. 1-8.8.  Fuel System.  The function of the fuel system is to inject a metered quantity of clean atomized fuel into the engine cylinders at a precise time near the end of the compression stroke of each piston.  The fuel system consists of the fuel tank,  fuel  filter/water  separator,  fuel  supply  pump,  fuel  injection  pump,  and  the  fuel  injectors.    The  fuel  tank  is  not mounted on the engine.  The fuel supply pump is mounted to the block and is driven by the camshaft.  The fuel injection pump is mounted on the front plate and is driven by an intermediate gear in the timing gear train meshing with crankshaft gear. 1-8.9.   Electrical  System.    The  electrical  system  is  24  VDC  operation  and  consists  of  a  battery  charging  alternator, starter, externally mounted batteries, and other items as required.  The battery charging alternator is mounted on front of engine and is belt driven.  When engine is operating, the battery charging alternator supplies 24 VDC to recharge the batteries  and  maintain  them  at  a  full  state  of  charge.    The  starter  is  mounted  on  the  flywheel  housing  and  when energized, engages the ring gear of the flywheel to rotate the engine. 1-2