Cooling System - Volvo MD2010 Workshop Manual

General
The engines are fresh water cooled and fitted with an
enclosed cooling system. The system is divided into
t wo circuits.
I n the inner circuit (fresh water system) the refrigerant is
pumped round by a circulation pump which is driven by
a V-belt from the crankshaft pulley.
The fresh water system works at a certain overpres-
sure, whereby the risk of boiling is reduced at high tem-
peratures. A pressure valve opens in the filler cap if the
pressure gets higher than normal.
The temperature of the refrigerant is regulated by a
thermostat.
The percolation in the sea water system is handled by a
gear driven pump of the blade type.
Heat is transferred from the refrigerant to the sea water
i n a heat exchanger.
As extra equipment the engine can be fitted with a sep-
arate expansion tank.
Fig. 104. Filler cap for refrigerant
Thermostat
The engines are provided with a thermostat, the sensor
body of which contains wax.
When the engine is cold the thermostat keeps the chan-
nel to the heat exchanger closed. The refrigerant then
passes via a a by-pass pipe directly back to the induc-
tion side of the pump. As the engine heats up the wax
i ncreases in volume and the thermostat gradually opens
the channel to the heat exchanger, at the same time as
the by-pass pipe is closed.
See "Technical data" for opening temperatures.
6 2

Cooling system

Sea water pump
The sea water pump is fitted on the timing gear housing
at the front end of the engine. The pump is driven via the
engine's timing gears. The pump wheel (impeller) is man-
ufactured of rubber and is replaceable.
Note: The pump wheel will become damaged if the pump
i s run dry.