Freshwater System - Volvo Penta D4 Operator's Manual

Freshwater system

The freshwater system is the engine's internal cooling system. It is a closed system and must always be filled
with a coolant that protects it against internal corrosion and freezing when the climate demands.
Freshwater circulates from the circulation pump in the engine block, around the cylinders and on to the turbochar-
ger and exhaust pipe. There is a thermostat mounted on the front of the exhaust pipe. The thermostat will start to
open at a certain temperature and will be fully open when the engine has attained normal operating temperature.
When the thermostat opens, the warm coolant passes through the heat exchanger where it is cooled by the water
in the engine's seawater system.
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Coolant. General
The coolant protects the engine from both internal cor-
rosion and frost damage.
IMPORTANT! The coolant must be a mixture of
ethylene glycol and water (to ASTM D4985)
IMPORTANT! The corrosion protection additives
become less effective as time passes, which me-
ans that the coolant must be changed, please re-
fer to "Maintenance schedule".
IMPORTANT! Never use only water as coolant.
Water quality
To avoid obstruction of the cooling system, resulting in
lower cooling capacity, always use clean water which
complies with the requirements in ASTM D4985.
If the water can not be purified to comply with this
demand, distilled water or pre-mixed coolant must be
used.
ASTM D4985:
Total solid particles
Total hardness:
Chloride
Sulfate
pH value
Silica
Iron
Manganese
Conductivity
Organic content, COD
Mn
< 340 ppm
< 9.5° dH
< 40 ppm
< 100 ppm
5.5–9
< 20 mg SiO /l
2
< 0.10 ppm
< 0.05 ppm
< 500 µS/cm
< 15mg kMnO /l
4