ignition lag is increased, causing detonation, which
results in rough operation. This may cause the engine to
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
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
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 manufacturers 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 manufacturers
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.