TM 5-3825-226-24 2. Make  sure  the  coolant  is  over  the  top  of  the radiator core. 3. Put   the   9S8140   Cooling   System   Pressurizing Pump Group on the radiator. 4. Get the pressure reading on the gauge to 3 psi (20    kPa)    more    than    the    pressure    on    the pressure cap. 5. Check the radiator for outside leakage. 6. Check all connections and hoses for the cooling system for outside leakage. 7. If  you  do  not  see  any  outside  leakage  and  the pressure reading on the gauge is still the same after 5 minutes, the radiator and cooling system does  not  have  leakage.    If  the  reading  on  the gauge   goes   down   and   you   do   not   see   any outside  leakage,  there  is  leakage  on  the  inside of    the    cooling    system.        Make    repairs    as necessary. The 9S8140 Cooling System Pressurizing Pump Group is used to test pressure caps and pressure relief valves,  and  to  pressure  check  the  cooling  system  for leaks. Gauge for Water Temperature Tools Needed: 9S9102 Thermistor Thermometer Group. If the engine gets too hot and a loss of coolant is a problem, a pressure loss in the cooling system can be the  cause.    If  the  gauge  for  water  temperature  shows that   the   engine   is   getting   too   hot,   look   for   coolant leakage. If   a   place   can   not   be   found   where   there   is coolant  leakage,  check  the  accuracy  of  the  gauge  for water     temperature.          Use     the     9S9102     Thermistor Thermometer Group. WARNING To  help  prevent  an  accident  caused by  parts  In  rotation,  work  carefully on an engine that has been started. Start  the  engine.    Put  a  cover  over  part  of  the radiator.          The     reading     on     the     gauge     for     water temperature  must  be  the  same  as  the  reading  on  the thermistor thermometer. 9S9102 THERMISTOR THERMOMETER GROUP INSTALLED (Typical Example) Temperature Regulator Test procedure for water temperature regulators: 1. Remove the regulator from the engine. 2. Put heat to a pan of water.  Get the temperature of the water to 197°  F (920 C). 3. Hang the regulator in the pan of hot water.  Put the  regulator  completely  under  the  water.    Do not let the regulator make contact with the pan. 4. Keep   the   temperature   of   the   water   at   197°F (920 C) for ten minutes.  Make the water move around.  This keeps all of the water at the same temperature. 5. After   ten   minutes,   remove   the   regulator   and immediately measure the distance the regulator is  opened.    See  the  SPECIFICATIONS  for  the correct opening distance. WATER PUMP PRESSURE CHECK Tools Needed: 9S8138 Pressure Gauge. 3B7722 Bushing. The  pressure  at  the  outlet  for  the  water  pump tells  if  the  shunt  system  and  water  pump  are  operating correctly.  To check the pump pressure, install pressure gauge  (2)  in  the  front  cover.    The  pressure  must  be  a minimum of 15 psi (105 kPa) at 2800 rpm. If  the  pump  pressure  is  less  than  the  minimum pressure:      First,   check   the   vent   tube   between   the radiator  top  tank  and  the  surge  tank;  it  must  have  an inside diameter of approximately .19 in.  (4.8 mm). Second  check  to  see  that  the  shunt  line  has  a minimum inside diameter of .75 in.  (19.1 mm). 2-71