8.2 PRIMARY CIRCUIT
This circuit cools down the engine, the lubricant oil, and often the exhaust manifold, as well. The pri-
mary circuit is enclosed and pressurised, and except for the keel-cooling system, it does not require
installation procedures. However, installers must pay special attention to the following:
Filling
The engine installation must guarantee easy filling and coolant level control. The filling volume ranges
from 8 to 10 litres per minute, and the procedure should be carried out by the dockyard personnel.
Make sure there are no air bubbles in the circuit, which might cause localised overheating and cavita-
tions. During filling, air could escape from the cooling system to the charging and expansion tank
installed on the engine. It is necessary to consult each engine use and maintenance manual to verify
whether to open the corresponding degassing plugs.
To ensure the total escape of the air and the complete filling of the circuit, the engine must be tilted
backward when installed.
Coolant tank
The engine has an expansion and charging tank to receive the coolant when its volume increases due
to heating, and to release it when the engine cools down.The tank filler has a cap to guarantee circuit
pressurisation calibrated at 0.5 - 1 bar. Pressurisation increases the liquid boiling point, so cavitations in
the circulation pump are avoided.To increase expansion volumes, an extra tank could be set up in some
cases. It should be connected to the main tank by a pipe fastened to the overfilled hose-end valve.This
tank cap must have a vacuum valve for liquid reflux during engine cooling.This non-pressurised second
tank, generally made of transparent material, is suitable to be installed to control the level easily, even
though it must also be periodically controlled in the main tank.
Heater
It is possible to set up a heater to obtain hot water, taking advantage of the coolant residual heat. Make
sure that:
■ the serpentine highest point is not higher than the filling tank point
■ in the connexion pipe there is a degassing plug near the serpentine upper section
■ liquid drainage and filling points are the ones suggested in the installation layout.
8.3 SECONDARY CIRCUIT
It cools down the engine coolant, the turbocharger air and transmission oil, if applicable.The water taken
through a seacock valve at the bottom of the hull is circulated by a positive-displacement pump placed
in the engine for this purpose. Small quantities of water may be allowed to drip behind the inter-
changers to refrigerate the packing gland.
The following items are part of the dockyard personnel’s responsibilities:
MARCH 2004 COOLING
8.84
MARINE ENGINES INSTALLATION
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