COOLING SYSTEMS
TYPE, OPERATION AND CARE
Cooling systems are provided on all types of gasoline engines. As the
heat generated by the constant explosions in the cylinders would soon
overheat and ruin the engine were it not cooled by some artificial
means.
=Circulation Systems.=--There are two types of water circulating
systems. The Thermo Syphon, and the Force Pump circulating systems.
[Illustration: Fig. 47. Thermo-Syphon Cooling System]
Fig. 47 shows how the water circulates in the Thermo-Syphon system. It
acts on the principle that hot water seeks a higher level than cold
water, consequently when the water reaches a certain temperature,
approximately 180° F., circulation commences and the water flows from
the lowest radiator outlet pipe up through the water jackets into the
upper radiator water tank, and down through the thin tubes to the lower
tank to repeat the process.
The heat is extracted from the water by its passage through the thin
metal tubing of the radiator to which are attached scientifically
worked out fins which assist in the rapid radiation of the heat. The
fan just back of the radiator sucks the air through the small tubes
which connect the upper and lower radiator tanks. The air is also
driven through between these tubes by the forward movement of the car.
=The Force Pump Circulation System.=--The Force Pump circulating system
is constructed in the same manner as the Thermo Syphon Cooling System.
The only difference in the two systems is that a small pump is attached
to the lower radiator pipe to force the circulation of the water.
The pump is usually of the centrifugal type and consists of a
fan-shaped wheel operated in a snugly fitted housing. The water enters
at the hub and is thrown out against the housing and is forced on by
the rapid action of the fan blades. Another type of pump is used by
some manufacturers which consist of two meshed gears of the same size,
which operate in a snugly fitted housing. These gears operate in a
direction toward each other, the water is carried forward or upward in
the space between the teeth, and is forced on when the teeth mesh and
fill the space.
=Overheating.=--Overheating may be caused by carbonized cylinders, too
much driving on low speed, not enough or a poor grade of lubricating
oil, spark retarded too far, racing the engine, clogged muffler, poor
carburetor adjustment, a broken or slipping fan belt, jammed radiator
tube, leaky connection, or low water.
=Radiator Cleaning.=--The entire circulation system should be
thoroughly cleaned occasionally. A good cleaning solution is made by
dissolving one-half pound of baking soda in three and one-half to four
gallons of soft water. The radiator is filled with the solution and
left to stand for twenty to thirty minutes. The hose is then removed
from the lower pipe, water is then turned into the radiator through
the filler spout until the system is thoroughly flushed out.
=Freezing.=--Unless an anti-freezing solution is used through the
cold months you are bound to experience trouble. The circulation does
not commence properly until the water becomes heated. It is apt to
freeze at low temperatures before circulation commences. In case any
of the small tubes are plugged or jammed they are bound to freeze and
burst open if the driver attempts to get along without a non-freezing
solution.
=Freezing Solution.=--Wood or denatured alcohol can be used to a good
advantage. The following table gives the freezing point of solutions
containing different percentages of alcohol.
20% solution freezes at 15° above zero.
30% solution freezes at 8° below zero.
50% solution freezes at 34° below zero.
A solution composed of 60% of water, 10% of glycerine, and 30% of
alcohol is commonly used, its freezing point being 8° below zero.
=Evaporation.=--On account of evaporation, fresh alcohol must be added
frequently in order to maintain the proper solution.
=Radiator Repairs.=--A small leak may be temporarily repaired by
applying brown soap, or white lead, but the repair should be made
permanent with solder as soon as possible. A jammed radiator tube is
a more serious affair. While the stopping up of one tube does not
seriously interfere with circulation, it is bound to cause trouble
sooner or later, and the tube will freeze in cold weather. Cut the tube
an inch above and below the jam and insert a new piece soldering the
connection. If the entire radiator is badly jammed or broken, it will
probably be advisable to install a new one.
=Air Cooling System.=--Air cooling has been developed to a point
where fairly good results are attained. This system has an advantage
over the circulating systems, in that the weight of the radiator and
water is done away with, and no trouble is experienced with stoppage
of circulation and leaky connection. This system, however, has its
drawbacks, in that it cannot be used successfully on the larger and
more compact engines. In order to allow the necessary large space for
radiation, the cylinders are heavily flanged and set separately. The
fan is placed in a much higher position than usual, in order that
the air current may strike the heads of the cylinders and circulate
downward. Compression is also lowered considerably to prevent heat
generation and pre-ignition. On account of the small size of the
cylinders and low compression, it is necessary to operate an air cooled
engine at a very high rate of speed to produce sufficient power for
automobile locomotion.
The fan must be kept in good working condition, and care should be
exercised in not allowing the engine to run idle for any length of
time.