Volvo D11 series, Installation Manual

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Cooling system
76
2
Seawater system
A standard feature of Volvo Penta diesel engines is
a closed cooling system, with freshwater circulating
in the cooling ducts and heat exchanger(s) of the en-
gine. In the heat exchanger(s), the engine coolant is
cooled by seawater.
Seawater circuit
The seawater is circulated in the system by the rub-
ber impeller of the seawater pump.
Seawater intake, sea cock, filter and sea-
water circuit
The seawater intake must be positioned so that the
seawater line to the pump is as short as possible. In
addition, the intake must be positioned so that air is
not drawn into the system at the planing threshold of
the boat or when rolling at sea.
NOTE! The greatest permitted suction head for the
pumps are 2 m (6.6") for D5/D7 and 3 m (0') for all
other engines.
The seawater intake, valve and strainer must have
sufficient flow area. For planing crafts, a sloted water
intake is recommended.
To avoid the seawater becoming blocked when pass-
ing through ice, the intake can be designed as shown
in the illustration.
. Valve for seawater intake.
2. Valve for flushing with hot water.
The sea cock must be easily accessible, and in cer-
tain cases it is a requirement that the valve is capable
of being closed from outside the engine compart-
ment.
In highly contaminated water and off coasts where
there is sand and sludge in the water, these sub-
stances are drawn into the seawater pump and will
reduce the life of the pump and the impeller. Foul-
ing and clogging of the seawater system contribute
to reduced cooling performance thus damaging the
engine. A seawater filter helps to extend the life of
the pump and reduces fouling of heat exchangers, oil
cooler and aftercooler.