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20. USE OF FUEL, COOLANT AND LUBRICANTS
20.2 COOLING SYSTEM
20.2.1 GENERAL
The cooling system operates under pressure which is controlled by the pressure relief valve in the radiator cap.
The belt driven water pump circulates the coolant through the engine block, cylinder heads, radiator, and engine oil
cooler. Circulation
is controlled by the thermostat which by-passes coolant flow around the radiator until the engine
reaches operating temperature.
Proper cooling is possible only when the system is sealed, the radiator cap gasket is in good condition, the pressure
relief valve and thermostats
are operating properly. The system is free of coolant and air flow restrictions and the
system is filled to the proper level.
Selection and maintenance
of the engine coolant is important to long engine life. The following information provides
recommendations
for selecting the engine coolant, maintaining the coolant inhibitors and servicing the cooling system.
The system operates successfully with a water/antifreeze
mixture or inhibited/conditioned
water as the coolant. Water
alone allows rust, scale deposits, and corrosion to occur within this system.
After 2000 hours or one year of operation, whichever comes first, the cooling system should be drained, flushed and
refilled.
20.2.2 WATER
Use water which has a low mineral content. Water used in conjunction
with antifreeze, coolant filters and inhibited
water must meet the following standards:
20.2.2.1 TOTAL HARDNESS
Not to exceed
170 parts per million (10 grains/gallon
maximum)
to prevent scale deposits. Water containing
dissolved
magnesium
and calcium (the usual reason for water hardness) above the specified amount will cause
scale deposits to develop in the engine.
20.2.2.2
CHLORIDES
Not to exceed 40 parts per million (2.5 grains/gallon
maximum) to prevent corrosion.
20.2.2.3
SULFITES
Not to exceed 100 parts per million (5.8 grains/gallon
maximum) to prevent corrosion.
20.2.2.4
DISSOLVED
SOLIDS
Not to exceed 340 parts per million (20 grains/gallon maximum) to minimize sludge deposits, scale deposits, corro-
sion or a combination
of these.
If any of the requirements cannot be met, use distilled, de-ionized, or de-mineralized water. To determine if local water
supplies meet these standards, water samples can be tested by water treatment laboratories.
Softened water that is
prepared using common salt (sodium chloride) contains excessive amounts of chlorides and should not be used.
REMARK
Never use water alone in the cooling system because corrosion will occur.
3-10
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