TM 10-3930-671-24 Engine Coolant Specification Refer  to  Section  2.    1,  Service  Specifications,  Cooling System. NOTE • For    maximum    cooling    efficiency, always    keep    the    cooling    system filled with the recommended coolant mixture    year    around    and    at    all ambient temperatures. • The use only of an antifreeze having a    low-silicate    additive    content    is strongly   recommended.       Silicates are    added    to    antifreeze    to    help protect  aluminum  cylinder  heads  in automotive engines.  During use, the silicate  additives  may  react  to  form gummy deposits that can block and seriously damage a cooling system. Low-silicate   antifreeze   is   available for heavy duty use.  Also, some tap waters  react  adversely  with  coolant chemicals.  If your local tap water is "hard," use distilled water. • The  cooling  system  is  initially  filled with  a  factory  installed  solution  of 50% water and 50% permanent  type antifreeze containing rust and corrosion   inhibitors.      You   should leave it in year around.  Plain  water may be used only in an  emergency, but   replace   it   with   the   specified coolant as soon as possible to avoid damage   to   the   system   or   engine. With  only  water  in  the  system,  do not let the engine run hot. • DO NOT USE ALCOHOL OR METHANOL ANTIFREEZE. Add  to  or  fill  radiator  only  with  recommended  coolant mixture   of   50%   water   and   50%   low-silicate   ethylene glycol   permanent-type   antifreeze   containing   rust   and corrosion inhibitors. Engine Coolant Level Check WARNING Do not remove the radiator cap when the   radiator   is   hot.      Steam   or   hot coolant  from  the  radiator  can  cause severe   burns.      Never   remove   the radiator    cap    while    the    engine    is running.    Stop  the  engine  and  wait until it has cooled. Remove   the   radiator   cap   only   with engine  stopped  and  when  engine  is cold. NOTE Fork lift truck applications require also checking  the  coolant  level  directly  in the  radiator.    Lift  truck  radiators  will plug-up  and  overheat  which  will  force coolant  into  overflow  reservoir  and  on out  at  the  cap.    This  results  in  a  low coolant level which exposes the transmission oil cooler causing engine/transaxle overheating. 1. The coolant level should be at the "COLD" level line  on  coolant  recovery  bottle  when  engine  is cold. 2. Coolant   level   in   the   radiator   should   also   be checked at lease once a day (or every 8 hours of operation)  to  make  sure  radiator  is  100%  full  at all times. 3. First, turn the cap slowly to release any pressure that may be in the radiator.  Then, push the cap fully  down  and  turn  to  release  and  remove  the cap. General Procedures NOTE If  coolant  has  to  be  added  more  than once  a  month  or  if  you  have  to  add more  than  one  quart  at  a  time,  check the  cooling  system  for  leaks,  or  other reasons, e.g. cooling system overheating.  See below. Open vent (petcock) on water pump when filling cooling system. 1. If    coolant    level    in    the    radiator    or    overflow reservoir is low, add a 50/50 mixture of specified coolant and water to the correct fill level. 2. If  the  cooling  system  requires  the  addition  of  a large   quantity   of   coolant,   and   the   engine   has been overheating: a) Inspect   radiator   for   blockage   of   air   flow through the fins.  Air clean the radiator. b) Check the tailpipe.  Be sure exhaust flow is not blowing into the radiator. c) Check fan belt and cooling fan drive control (as applicable). d) Check   and   be   sure   fan   is   not   installed backwards (a common problem). F-94