ignition  lag  is  increased,  causing  detonation,  which results in rough operation. This may cause the engine to stall. If the water temperature is higher than normal, the engine  may  not  cool  properly  and  may  suffer  heat damage. Water temperature is controlled primarily by a thermostatic   valve   (thermostat).   The   thermostat normally operates with a minimum of trouble. High or low   cooling   water   temperature   may   indicate   a malfunctioning thermostat. But before you remove the thermostat to check it, check to see whether the improper temperature  may  be  caused  by  an  insufficient  engine load or an inaccurate temperature gauge. When  you  suspect  that  the  thermostat  is  not operating properly, remove it from the engine and test it. Use the following procedure to test the thermostat: 1.   Obtain   an   open-topped   container   such   as   a bucket or a pot. 2. Heat the water to the temperature at which the thermostat  is  supposed  to  start  opening.  This temperature   is   usually   specified   in   the   appropriate technical manual. Use an accurate thermometer to check the water temperature. Use a hot plate or a burner as a source  of  heat.  Stir  the  water  frequently  to  ensure uniform distribution of the heat. 3. Suspend the thermostat by a string or a wire so that operation of the bellows will not be restricted. 4. Immerse the thermostat and observe its action. Check  the  thermometer  readings  carefully  to  see whether  the  thermostat  begins  to  open  at  the recommended   temperature.   (The   thermostat   and thermometer must NOT touch the container.) 5.  Increase  the  temperature  of  the  water  until  the specified  FULL  OPEN  temperature  is  reached.  The immersed   thermostat   should   be   fully   open   at   this temperature. Replace the thermostat if it does not open when you test  it,  or  if  the  temperatures  at  which  the  thermostat opens  and  closes  vary  more  than  allowed  from  the manufacturer’s    specifications. The  Fulton-Sylphon  automatic  temperature regulator  is  relatively  trouble-free.  The  unit  controls temperatures  by  a  valve  that  bypasses  some  water around the cooler. This system provides a full flow of the water, although only a portion may be cooled. In other  words,  the  full  volume  of  cooling  water  is circulated at the proper velocity, which eliminates the possibility  of  steam  pockets  in  the  system. Usually,  if  the  automatic  temperature  regulator  fails to maintain cooling water at the proper temperature, it simply  needs  to  be  readjusted.  However,  the  element  of the valve may be leaking or some part of the valve may be  defective.  Failure  to  follow  the  proper  adjustment procedure is the only cause for improper adjustment of an automatic temperature regulator. Check and follow the  proper  procedure  in  the  manufacturer’s  technical manual issued for the specific equipment. Adjust the regulator by changing the tension of the spring  (which  opposes  the  action  of  the  thermostatic bellows) with a special tool that turns the adjusting stem knob or wheel. Increasing the spring tension raises the temperature  range  of  the  regulator,  and  decreasing  it lowers the temperature range. When  you  place  a  new  valve  of  this  type  into service, you must take a number of steps to ensure that the  valve  stem  is  the  proper  length  and  that  all  scale pointers   make   accurate   indications.   Make   all adjustments   according   to   the   valve   manufacturer’s technical  manual. Obstruction in the Exhaust System This  type  of  trouble  seldom  occurs  if  proper installation and maintenance procedures are followed. When a part of an engine exhaust system is restricted, there will be an increase in the exhaust back pressure. This  may  cause  high  exhaust  temperatures,  loss  of power,  or  even  stalling.  An  obstruction  that  causes excessive  back  pressure  in  an  exhaust  system  is generally associated with the silencer or muffler. The manifolds of an exhaust system are relatively trouble-free  if  related  equipment  is  designed  and installed properly. Improper design or installation may cause  water  to  back  up  into  the  exhaust  manifold.  In some  installations,  the  design  of  the  silencer  may  cause water to flow into the engine. The source of water that may enter an engine must be found and eliminated. This may require replacing some parts of the exhaust system with components of an improved design or may require relocating  such  items  as  the  silencer  and  piping. Inspect exhaust manifolds for water or symptoms of water.  Accumulation  of  salt  or  scale  in  the  manifold usually indicates that water has been entering from the silencer.  Turbochargers  on  some  engines  have  been known to seize because salt water entered the exhaust gas  turhine  from  the  silencer.  Entry  of  water  into  an engine may also be detected by the presence of corrosion or of salt deposits on the engine exhaust valves. 3-32