Mercedes-Benz OM 471 Introduction Into Service Manual page 195

System components
Function
1 Oil/coolant module
3 Oil filter
5 Oil/water heat exchanger
6 Coolant pump
7 Coolant thermostat
8 Initial filling valve
9 Engine oil inlet (from oil pump)
10 Engine oil outlet (to main oil ducts in
crankcase)
11 Engine oil drain from oil filter (for oil
filter change)
12 Coolant outlet (to crankcase)
13 Coolant inlet (from coolant bypass
duct)
14 Coolant outlet (to exhaust gas
recirculation cooler)
15 Coolant inlet (from coolant expansion
reservoir, when the coolant
expansion reservoir is at the front or
the heater return, when the coolant
expansion reservoir is at the rear)
Filter the engine oil
The engine oil flows, depending on the position of the oil
thermostat (2), either straight into the oil filter housing (3) or
after it has passed through the oil>water heat exchanger (5).
In the oil filter housing the engine oil flows from the outside
inwards through the oil filter (3) and on to the support dome,
where it is filtered The worm>shaped characteristic of the support
dome routes the filtered engine oil upwards to the tip of the
support dome, where it flows in through several holes in the
support dome. Within the support dome the engine oil is initially
routed downwards and then to the rear of the oil/coolant module
(1), where the engine oil outlet (10) is located. The filtered engine
oil then flows through the engine oil outlet (10) into the
crankcase and the main oil ducts located there, and therefore
back into the oil circuit.
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Regulating the coolant temperature
The coolant temperature is regulated through the coolant
thermostat (7). When the engine is cold, the coolant pump (6)
makes the coolant circulate inside the engine. The coolant from
the coolant short>circuit duct flows over the coolant inlet (13) into
the oil/coolant module (1) where it is routed at the closed coolant
thermostat (7) past the coolant pump (6) to the coolant outlet
(12). When the engine operating temperature is reached, the
cooler circuit is activated when the coolant thermostat (7) is
opened.
192
16 Coolant inlet (from coolant expansion
reservoir, when the coolant
expansion reservoir is at the rear or
the heater return, when the coolant
expansion reservoir is at the front)
– This printout will not be recorded by the update service. Status: 09 / 2011 –
17 Coolant inlet (return from compressor
and fuel cooler)
18 Coolant inlet (from cooler)
A Coolant
B Engine oil
Regulate the engine oil temperature
To regulate the engine oil temperature an oil thermostat (2) is
located immediately downstream of the engine oil inlet.
At an engine temperature of less than 115 ∞C the engine oil is
routed through the open oil thermostat (2) over a bypass straight
into the oil filter (3). At 115 ∞C the oil thermostat (2) closes the
bypass and the engine oil flows first to the oil>water heat
exchanger (5) before reaching the oil filter (3).
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The coolant from the cooler flows over the coolant inlet (18) and
the open coolant thermostat (7) into the oil/coolant module (1).
Depending on the position of the coolant thermostat (7), more or
less coolant flows through the cooler or directly over the coolant
bypass line to the coolant pump (6). The temperature of the
coolant in the coolant circuit is regulated in this way.
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