Cooling system
Engine M132
39
Introduction of the smart fortwo, Model Series 451
Coolant circuit
In the small cooling circuit, the coolant is pumped
through the engine, the heater heat exchanger and
back to the engine via the expansion reservoir by the
coolant recirculation pump.
In the large coolant circuit, the coolant flows from the
thermostat straight to the radiator and on to the
coolant recirculation pump.
The switchover between the small and large coolant
circuit is performed by the thermostat depending on
the coolant temperature.
In the expansion reservoir the circuit is split again,
with one stream flowing direct to the coolant recircu-
lation pump and the other passing through the radi-
ator.
The coolant fan motor is switched on or off depending
on the engine temperature recorded by the coolant
temperature sensor and cools the coolant.
P20.00-2339-00
1 Radiator
2 Expansion reservoir
3 Coolant return line
4 Coolant feed line (large circuit)
5 Coolant pump
6 Coolant pump belt pulley
7 Thermostat
8 Coolant feed line (small circuit)
9 Heater heat exchanger
10 Coolant pipe
B11/4 Coolant temperature sensor
M4/2 Coolant fan motor
SN_Typ 451_us.book Seite 39 Freitag, 30. November 2007 1:56 13
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