COOLING  SYSTEM COOLING   SYSTEM TM    5-3805-258-24-1 T E S T I N G  A N D  A D J U S T I N G The engine has a pressure type cooling system. A pressure type cooling system gives two advantages. The first advantage is that the cooling system can operate safely at a temperature that is higher than the normal point where water changes to steam. The second  advantage  is  that  this  type  system  prevents cavitation (air in inlet of pump) in the water pump. With this type system it is more difficult for an air or steam pocket to form in the cooling system. The cause for an engine getting too hot is generally because regular inspections of the cooling system were not done. Make a visual inspection of the cool- ing system before testing with testing equipment, VISUAL INSPECTION OF THE COOLING SYSTEM 1. 2. 3. 4. 5. 6. 7. 8. Check coolant level in the cooling system. Look for leaks in the system. Look for bent radiator fins. Be sure that air flow through the radiator does not have a restriction. Inspect the drive for the fan. Check  for  damage  to  the  fan  blades. Look for air or combustion gas in the cooling system. Inspect the pressure cap and the sealing surface for the cap. The sealing surface must be clean. Look for large amounts of dirt in the radiator Test Tools for Cooling System Tools    Needed: 9S9102   Thermistor   Thermometer    Group. 9S7373    Air   Meter    Group. 6V3121    Multitach     Group. 9S8140    Cooling    System    Pressurizing     Pump    Group. The 9S9102 Thermistor Thermometer Group is used in the diagnosis of overheating (engine running too hot) or overcooking (engine runs too cool) prob- lems. This group can be used to check temperatures in several different parts of the cooling system. 9S9102   THERMISTOR   THERMOMETER   GROUP core and on the engine. TESTING  THE  COOLING  SYSTEM Remember that temperature and pressure work together.  When  making  a  diagnosis  of  a  cooling system  problem,  temperature  and  pressure  must both be checked. Cooling system pressure will have an effect on cooling system temperatures. For an example, look at the chart to see the effect of pressure and  the  height  above  sea  level  on  the  boiling  point (steam) of water. A32417.2X1 C O O L I N G     S Y S T E M     P R E S S U R E ALTITUDE MSTSXS FEIH 432a 14,0M 3700 1 Z,ooo 30W 10,  OOO 2400 8,000 mm 9 S 7 3 7 3     A I R     M E T E R     G R O U P s.mo I 2W 4.oca The 9S7373 Air Meter Group is used to check the w 2.000 SSA LSVEL  O air flow through the radiator core. 82 M 93 49 IM 110 I  15 121”C 140 120   200 210 220 330 240 250- F BOILING     POINT     OF     WATER 4-31