Engine
SHOP MANUAL
Ch 1 page 39
The reductant pump sucks reductant from the reductant tank, filters and builds up pressure for the reductant
which is then fed to the reductant doser.
The reductant pump is an electrically driven diaphragm pump with a filter for cleaning the reductant. The reduc-
tant pump is heated using the engine’s coolant at low outdoor temperatures in order to thaw frozen reductant or
prevent it freezing.
1 Pump unit
2 Valve block
3 Reductant filter
4 Cover
5 Connections for coolant
6 Ventilation
7 Internal hexagon bolt
8 Connection for electrical connector
9 Connections for reductant
10 Electric motor for diaphragm pump
The illustration below (figure 59) shows a section through the valve block viewed from below.
Reductant is sucked through the intake (1) and reductant filter in the valve block (3) and then through a port
(6) to the pump chamber, where reductant pressure is built up. If the reductant pressure exceeds 13 bar in
the pump, the overflow valve (5) and check valve (7) open, reducing the reductant pressure in the pump. The
amount of reductant pumped to the reductant doser can be varied by regulating the speed of the electric motor
between 800 and 3500 revolutions per minute.
If the reductant freezes in the reductant pump at low outdoor
temperatures when it is non-operational, which takes place at
approx. -11°C, there is a damping element (4) in the valve block
that is compressed when the reductant expands during freezing.
1 Intake, reductant
2 Outlet, reductant
3 Reductant filter
4 Damping element
5 Overflow valve
6 Port to pump chamber
7 Check valve
Reductant pump, function
Figure 59
Figure 58
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