Mercedes-Benz OM 471 Introduction Into Service Manual page 119

System components
Function
8 AdBlue" inlet
9 Intake filter
10 AdBlue" outlet
12 Coolant inlet
13 Coolant outlet
14 Pressure limiting valve
15 Main filter
M25 SCR delivery pump
After the engine starts, the exhaust aftertreatment (ACM) control
unit (A60) actuates the pump module (1) or more accurately, the
SCR control unit (A58) integrated into it. This switches the SCR
delivery pump (M25), so that AdBlue" is sucked in from the
AdBlue" container and pumped at an operating pressure of
approx. 10 bar towards the AdBlue" metering device (A67).
Because the AdBlue" metering device (A67) is cooled be
circulation through circulating AdBlue", AdBlue" is pumped
continuously, irrespective of whether injection is necessary or not.
The AdBlue" that is not required or not injected flows back
through the return line to the AdBlue" container.
116
– This printout will not be recorded by the update service. Status: 09 / 2011 –
Heating
A duct inside the connecting body (4) enables the pump module
(1) to have engine coolant flow through it for heating or
defrosting. The coolant inflow is regulated by an engine mounted
solenoid valve as a function of the temperature by the engine
management (MCM) control unit (A60).
Delayed>off running
To avoid any damage through overheating on the AdBlue"
metering device (A67), the pump module (1) continues to pump
AdBlue" for some time after the engine stops so that the cooling
can be maintained for a longer period.
W14.40>1560>03