Service manual

G420F(FE) Service Manual Chapter 3. Engine Mechanical System 59
Filling at over 20 liters per minute can cause air
pockets in the cooling system.
After draining and refilling the cooling system,
operate the engine with the radiator cap removed
until the coolant reaches normal operating
temperature and the coolant level stabilizes. Add
coolant as necessary to fill the system to the proper
level.
Operate with a thermostat in the cooling system all
year-round. Cooling system problems can arise
without a thermostat.
Coolant Water
Hard water, or water with high levels of calcium and
magnesium ions, encourages the formation of
insoluble chemical compounds by combining with
cooling system additives such as silicates and
phosphates.
The tendency of silicates and phosphates to
precipitate out-of-solution increases with increasing
water hardness. Hard water, or water with high
levels of calcium and magnesium ions encourages
the formation of insoluble chemicals, especially after
a number of heating and cooling cycles.
DOOSAN prefers the use of distilled water or
deionized water to reduce the potential and severity
of chemical insolubility.
Acceptable Water
Water Content Limits (ppm)
Chlorides (CI) 40 maximum
Sulfates (SO4) 50 maximum
Total Hardness 80mg/ maximumℓ
Total Solids 250 maximum
pH 6.0 ~ 8.0
ppm = parts per million
Using water that meets the minimum acceptable
water requirement may not prevent drop-out of
these chemical compounds totally, but should
minimize the rate to acceptable levels.
Antifreeze
DOOSAN recommends selecting automotive
antifreeze suitable for gasoline engines using
aluminum alloy parts. The antifreeze should meet
ASTM-D3306 standard.
Make proper antifreeze additions.
Adding pure antifreeze as a makeup solution for
cooling system top-up is an unacceptable practice. It
increases the concentration of antifreeze in the
cooling system which increases the concentration of
dissolved solids and undissolved chemical inhibitors
in the cooling system. Add antifreeze mixed with
water to the same freeze protection as your cooling
system.