TRUCK SERVICE MANUAL TM 5-4210-230-14&P-1 COOLING SYSTEM INTRODUCTION The  purpose  of  the  cooling  system  is  to  maintain  the most   efficient   operating   temperature   of   an   engine   without causing damage to the components.  Approximately 1/3 of the energy produced when fuel burns is converted into power by the engine.  The other 2/3 of the energy must be disposed of by the exhaust system and the cooling system or engine damage will result. Basically,  the  circulation  of  coolant  through  the  cooling system  relies  upon  the  water  pump.  The  water  pump  draws coolant from the radiator and forces it through the water jackets and  cylinder  heads,  where  it  accumulates  heat.    The  coolant then  flows  to  the  upper  radiator  tank  and  down  through  the radiator where it is cooled by air drawn through the radiator fins. The    damages    or    effects    caused    by    cooling    system neglect are usually gradual and are therefore often overlooked. This  manual  provides  the  reader  basic  component  knowledge, maintenance procedures, service intervals, trouble-shooting and coolant and inhibitor recommendations. COOLANT The  selection  and  maintenance  of  the  engine  coolant  is as important to long engine life as the selection and changing of the  engine  lubricating  oil  and  oil  filters.    The  following  section provides IH's recommendations for selecting the engine coolant and maintenance of the coolant inhibitors. A.  COOLANT SELECTION IH  engines  will  operate  successfully  with  a  water/anti- freeze  mixture  or  inhibited  water  as  the  coolant.    Never  use water  alone  as  it  allows  rust,  scale  deposits  and  corrosion  to occur within the engine. 1 Water Water    used    in    the    cooling    system    must    meet    the following standards: a. Total   Hardness-not   to   exceed   170   parts   per million  (10  grains/gallon  maximum)  to  prevent scale    deposits.        Water    containing    dissolved magnesium  and  calcium  (the  usual  reason  for water hardness) above the specified amount will cause scale deposits to develop in the engine. b. Chlorides-not to exceed 40 parts per million (2.5 grains/gallon maximum) to prevent corrosion. c. Sulfates-not to exceed 100 parts per million (5.8 grains/gallon maximum) to prevent corrosion. d. Dissolved   Solids-not   to   exceed   340   parts   per million  (20 grains/gallon maximum) to minimize sludge  deposits,  scale  deposits,  corrosion  or  a combination of these. If  any  of  the  above  requirements  cannot  be  met,  use distilled,  de-ionized  or  de-mineralized  water.    Water  samples can  be  tested  by  water  treatment  laboratories  to  determine  if local  water  supplies  meet  these  standards.    "Softened"  water that is prepared using common salt (sodium chloride) contains excessive   amounts   of   chlorides   which   will   interfere   with   the water softening capabilities of coolant filters using ion-exchange resins. 2. Anti-Freeze IH    Anti-Freeze    and    Coolant    contains    all    necessary inhibitors  and  has  been  tested  for  use  in  IH  products.    It  is  an ethylene  glycol  type  anti-freeze  and  compatible  with  chromate and non-chromate type coolant filters. Several   factors   should   be   considered   for   successful operation when using ethylene glycol type anti-freezes. a. The  boiling  point  of  ethylene  glycol  anti-freeze solutions   is   higher   than   plain   water   but   their ability to transfer heat is less.  Therefore in hot weather,   coolant   temperatures   will   run   higher than systems containing plain water.  This also holds     true     for     engine     lubricating     oil     and transmission oil temperatures where oil to water coolers are used. b. An  anti-freeze  concentration  greater  than  68% will  adversely  affect  freeze  protection  and  heat transfer rates. Anti-freeze concentrations between  68  and  100%  actually  have  a  higher freezing point than a 68% anti-freeze concentration.  Due to the higher freezing point and reduced heat transfer rates, concentrations greater than 68% should not be used.  It is also important   to   remember   that   anti-freeze   may retain  its  freeze  protection  for  more  than  one season but coolant conditions must be added to maintain   corrosion   protection.      The   following chart  illustrates  the  freezing  point  of  anti-freeze according to its percentage    CTS-2019P  Page 3 PRINTED IN UNITED STATES OF AMERICA