TM 5-3895-382-24 Cooling System Specifications General Coolant Information Many   engine   failures   could   be   avoided   with   proper cooling system maintenance. Cooling system maintenance   is   as   important   as   fuel   and   lubricating system maintenance.  Coolant quality is as important as the quality of fuel and lubricating oil. The   three   main   functions   that   coolant   serves are: Adequate heat transfer and anti-boil protection Cavitation erosion and corrosion protection Freeze protection Coolant is normally composed of three elements: Water Additives Glycol Water Distilled  or  deionized  water  is  recommended  for  use  in cooling systems.  DO NOT use hard water, tap water, or salt  softened  tap  water  in  engine  cooling  systems.    If distilled  or  deionized  water  is  NOT  available,  use  water that meets the minimum acceptable requirements. MINIMUM ACCEPTABLE WATER Water Content Limits in grain per gallon (parts per million) Chloride 2.4 (40) maximum Sulfates 5.9 (100) maximum Total Hardness 10 (170) maximum Total Solids 20 (340) maximum pH 5.5 - 9.0 NOTICE Water  that  does  not  meet  the  minimum  acceptable limits  will  reduce  engine  service  life  when  used  in cooling systems. If  you  are  not  sure  of  the  content  of  the  water,  contact your   Caterpillar   dealer,   your   local   water   department, your  agricultural  agent,  or  an  independent  laboratory  to analyze the water. Additives Additives   must   be   included   in   all   coolant   mixtures. Additives  help  prevent  the  formation  of  rust,  scale,  and mineral     deposits.          Additives     protect     metals     from corrosion, prevent liner cavitation, and contain antifoaming    agents.        Additives    are    depleted    during engine operation and need to be replenished.  Additives can be replenished through the addition of supplemental coolant   additives   (used   with   conventional   coolants)   or Extender (used with Caterpillar Long Life Coolant/Antifreeze) . Nitrites   or   nitrite   and   molybdate   additives   protect   the cylinder   liner   from   cavitation   corrosion.      Nitrites   are depleted,  creating  the  need  for  additives  or  Extender. Additives and Extender also contain other inhibitors that can be depleted from cooling systems. An  insufficient  additive  concentration  does  not  provide adequate  protection  for  cooling  systems.    An  excessive additive concentration can cause additives to drop out of the solution, deposit inside the cooling system, or form a gel in the radiator.  Deposits can be in the form of sludge and   scale   which   accumulate   on   hot   engine   surfaces. Deposits  reduce  cooling  system  effectiveness,  or  cause water pump leaks. To maintain conventional cooling system protection, it is necessary    to    monitor    supplemental    coolant    additive concentration.  Maintain the proper additive levels in the cooling system. Operation Section Cooling System Specifications 1-23