TM 5-3895-383-24 Cooling System Specifications General Coolant Information SMCS Code:  1350; 1395 NOTICE Adding  coolant  to  an  overheated  engine  could  result  in damage  to  the  engine.    Allow  the  engine  to  cool  before adding coolant. If  the  machine  is  to  be  stored  in,  or  shipped  to,  an  area with  freezing  temperatures,  the  cooling  system  must  be protected to the lowest outside (ambient) temperature. The engine cooling system is normally protected to -28°C (-20° F) with Caterpillar Antifreeze, when shipped from the factory unless special requirements are defined. NOTICE In  cold  weather,  frequently  check  the  specific  gravity  of the coolant solution to ensure adequate protection. Clean     the     cooling     system     for     the     following     reasons: contamination of the cooling system, engine overheating, and foaming in the radiator. Air   pockets   can   form   in   the   cooling   system   if   the   cooling system is filled at a rate that is greater than 20 L (5 US gal) per minute. After   you   drain   the   cooling   system   and   after   you   refill   the cooling   system,   operate   the   engine.      Operate   the   engine without   the   radiator   cap   until   the   coolant   reaches   normal operating  temperature  and  the  coolant  level  stabilizes.    Make sure that the coolant is maintained to the proper level. NOTICE Never    operate    an    engine    without    water    temperature regulators   in   the   cooling   system.      Water   temperature regulators   help   to   maintain   the   engine   coolant   at   the proper operating temperature.  Cooling system problems can develop without water temperature regulators For     more     detailed     information,     refer     to     the     following publications:      Special   Publication,   SEBD0518,   "Know   Your Cooling System" and Special Publication, SEBD0970, "Coolant and Your Engine". Many   engine   failures   are   related   to   the   cooling   system. Cooling    system    failures    include    the    following    problems: overheating,  leakage  of  the  water  pump,  plugged  radiators, and cylinder liner pitting.  These failures could be avoided with proper   cooling   system   maintenance.      Maintenance   of   the engine   coolant   is   important   to   the   engine   life   and   to   the performance.  Maintaining the quality of the engine's coolant is as important as maintaining the quality of the engine's fuel and lubricating oil. Coolant provides three main functions: Coolant  provides  cooling  by  transferring  heat  from  the engine to the air. Coolant provides corrosion protection. Coolant   provides   anti-boil   protection   and   antifreeze protection. Coolant is normally composed of three elements: Water Additives Glycol Water NOTICE Never   use   water   alone   without   Supplemental   Coolant Additive   (SCA's)   or   inhibited   coolant.      Water   alone   is corrosive at engine operating temperatures and does not provide adequate boil protection. Water is used to transfer the heat in the coolant solution.  For this reason, it is important to use water that meets the following recommendations. Water that does not meet the recommendations can interfere with the transfer of heat.  This water can also be corrosive. Distilled water or deionized water is recommended for use in cooling  systems.    Do  not  use  hard  water  in  engine  cooling systems.  Also, never use water that has been softened with salt.  If distilled water or deionized water is not available, use water that meets the minimum requirements that are listed in the following table. NOTICE All   Caterpillar   diesel   engines   equipped   with   air-to-air aftercooling  (ATAAC)  require  a  minimum  of  30  percent glycol to prevent water pump cavitation. Maintenance Section Cooling System Specifications 1-23