Chevrolet Fleetmaster Series 1947 Owner's Manual page 33

It
may be advisable to install new radiator and heater hose,
especially when ethylene glycol or glycerine anti-freezing solutions
are used. Ethylene glycol and glycerine have a tendenfY to shrink
rubber that previously has been swollen by the absorption of
water, and leaks may develop.
The water pump seal must be leaktight, not only to avoid loss
of liquid, but to prevent air from being drawn into the cooling
system. Aeration of the cooling liquid causes foaming and pro-
motes oxidation, which may result in serious corrosion.
After the anti-freezing solution has been installed, the entire
system, including the hose connections, cylinder head gasket and
pump, should be inspected regularly to insure that no leaks have
developed .
The use of additional rust preventives, or inhibitors, is not
recommended with "GM Anti-Freeze," "GM Ethylene Glycol,"
or with other anti-freeze· preparations that have been chemically
treated or compounded for use in automotive cooling systems.
Loss of Anti-Freezing Solutions:......
Anti-freeze, or water, or both may be lost from the cooling sys-
tem through leaks, evaporation, boiling, foaming, or expansion.
Loss through excessive evaporation or boiling may be caused
by impaired circulation or through the use of a high temperature
thermostat.
Loss by expansion is a result of overfilling. In the average
cooling system, the anti-freezing solutiori expands approximately
2 pints on heating from 30° F . to 160° F., and a corresponding
space should be left when adding liquid to the radiator.
A hydrometer test will indicate whether anti-freeze, or water,
or both should be. added to bring the solution to the proper level
and to maintain the desired freezing point.
Testing-Some
devices, used for test-
ing anti-freezing solutions, will indicate the correct freezing point
only when the test is made at a specific temperature. Other
testers, provided with thermometers and tables, indicate the
freezing points corresponding to readings made at various tem-
peratures. Disregarding the temperature of the solution, when
tested, may cause an error as large as 30° F.
Some testing devices are made to test only one kind of anti-
freezing solution. Others have several scales and may be used for
the corresponding kinds of anti-freeze.
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