2005 BMW 545i engine coolant

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N62 Engine
Cooling Radiator
The radiator is made from aluminum and is divided into a high-temperature section and a
low-temperature section by a partition wall (see coolant circuit diagram). The coolant first
flows into the high-temperature section and then back to the engine, cooled.
Some of the coolant flows through an opening in the radiator partition wall to the low-tem-
perature section where it is cooled further. The coolant then flows from the low-tempera-
ture section (when the ÖWT thermostat is open) into the oil/coolant heat exchanger.
Coolant Expansion Tank
The expansion tank is mounted on the right hand wheel housing (engine compartment).
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The expansion tank should never be filled above the Max marking. Excess coolant is
expelled by the pressure relief valve in the cap as it heats up. Avoid overfilling the expan-
sion tank because the cooling circuit design ensures very good “self bleeding”.
Cooling Components
1. Cooling Radiator 4. Engine oil/air heat exchanger connection
2. Expansion Tank (hot countries only)
3. Water Pump 5. Transmission oil/coolant heat exchanger

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N62 Engine
Transmission Oil/Coolant Heat Exchanger
The transmission oil/coolant heat exchanger ensures that the transmission oil is heated up
quickly and also that it is appropriately cooled. When the engine is cold, the transmission
oil/coolant heat exchanger thermostat switches into the engine's recirculated coolant cir-
cuit. This allows the transmission oil to heat up as quickly as possible (with the engine
coolant).
When the return flow water temperature reaches 82 ºC, the thermostat switches the trans-
mission oil/coolant heat exchanger to the low-temperature coolant radiator circuit (refer to
the cooling circuit diagram) to cool the transmission oil.
Electrically Operated Fan
The electric fan is integrated in the cooling module and is mounted directly in front of the
radiator. The speed is regulated by the ECM.
Viscous Coupling Fan
The viscous coupling fan is driven by the water pump. The noise output and the perfor-
mance of the fan coupling and the fan wheel have been optimized as compared with the
E38M62. The viscous coupling fan is used as the final level of cooling and switches on at
an air temperature of 92 ºC.
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N62 Engine
Engine Block
Oil Sump
The oil sump consists of two parts. The upper section of the oil sump is made from cast
aluminum and is sealed to the crankcase with a rubber-coated sheet steel gasket. This
section of the oil sump has a cross shaped cut out oil filter element recess. The upper sec-
tion of the oil sump is inter connected to the oil pump and is sealed with a sealing ring. The
double panel (noise insulation) lower section of the oil sump is flanged to the upper section
of the oil sump.
Crankcase
The crankcase has a one-piece “open deck” design and is made entirely from AluSil. The
cylinder walls are hardened using a specific procedure (exposure honing). Exposure hon-
ing involves treating the cylinders with a special “soft stripping”. This removes the aluminum
from the cylinder surface and the hard silicone particles remain.
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1. Flow to engine “V” (return coolant collection area) 2. External cylinder bank wall
Oil Sump Components
1. Upper Section of The Oil Sump
2. Oil Pump
3. Oil Level / Condition Sensor
4. Lower Section of The Oil Sump
5. Oil Filter Housing
6. Oil Drain Plug
42-03-65
42-03-66 42-02-67