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N62 Engine
The coolant flows to the rear of the engine block, from there through the side channels to
the cylinder walls and then into the cylinder heads (lower left picture). The cast aluminum
cover at the rear of the engine block (with sealing bead) is shown on the lower right.
Water Pump/Thermostat Housing
The water pump is combined with the thermostat housing and is bolted to the timing case
lower section.
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The impeller is made from reinforced plastic.
42-02-59
Water Pump / Thermostat Housing
1. Map-controlled themostat (radiator cool return flow).
2. Electrical connection for Thermostat Heating element.
3. Thermostat Mixing Chamber
4. Temperature Sensor (hot coolant from engine)
5. Radiator in-flow (hot coolant from engine)
6. Heat exchanger (transmission oil return flow)
7. Leakage Chamber (evaporation space)
8. Alternator in-flow (cool supply)
9. Water Pump
10. Expansion Tank Connection
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N62 Engine
Map-controlled Thermostat
The map-controlled thermostat allows the engine to be cooled relevant to operating con-
ditions. This reduces fuel consumption by approximately 1-6%. The electrical connections,
the design and the map-controlled thermostat response have been enhanced. The map-
controlled thermostat function is the same as previous engines (M62).
Cooling Module
The cooling module contains the following main cooling system components:
• Cooling radiator
• Air conditioning condenser
• Transmission oil/water heat exchanger
• Hydraulic fluid radiator
• Engine oil radiator
• Main electric fan
• Fan shroud for viscous coupling fan
All the components (with the exception of the transmission oil radiator) can be removed for
repairs without disassembling any other coolant circuit. All connections have been fitted
with the quick-release coupling which are used in current models.
Maped-Controlled Thermostat
1. Radiator Return Flow To Thermostat
2. Connection for Thermostat Heating Element
3. Temperature Sensor
4. Radiator in-flow (hot coolant from engine)
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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
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N62 Engine
Crankshaft
The N62 uses an inductively hardened cast-iron crankshaft. The crankshaft has five main
bearings (familiar 4 bolt cast iron caps) and is hollowed around bearing journals 2, 3, and
4 for weight reduction. The fifth bearing is also the “thrust” bearing.
The crankshaft stroke for the B44
is 82.7 mm.
Crankshaft Thrust Bearing
The thrust bearing halves are multiple pieces that are assem-
bled as one part for the the number five main bearing at the
rear of the engine. The bearing thickness conforms to the
familiar triple classification system (yellow - green - white).
Piston and Connecting Rod
The reduced weight cast piston contains integrated
valve reliefs in the piston crown. The pistons are made
from high-temperature aluminum alloy equipped with
three piston rings.
• First piston ring groove = square ring
• Second piston ring groove = taperface ring
• Third piston ring groove = three-part oil control ring
The forged steel connecting rod and cap is separated
by the familiar “cracked” process. The connecting rod
(large end) is angled at 30º allowing sufficient articula-
tion in a very compact space. The pistons are cooled
by oil jets spraying under the exhaust side of the pis-
ton crown.
Crankshaft
1. Crankshaft Sprocket
2-4. Hollowed Area (Weight Reduction)
42-02-68
42-02-70
42-03-70
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N62 Engine
Lubrication System
Crankcase with oil jets
The engine oil is supplied by the oil pump to the lubrication points in the engine block and
is pumped into the cylinder heads. The following components in the crankcase and cylin-
der head are supplied with engine oil:
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• Crankshaft bearings
• Oil jets for piston cooling
• Oil jet for the drive chain (bank 5-8)
• Tensioning rail for drive chain (bank 1-4)
Oil Check Valves
Three oil check valves are inserted into each cylinder head from the outside. This prevents
the engine oil from draining out of the cylinder head and the VANOS units.
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• Chain tensioner
• Guide rail on cylinder head
• Hydraulic valve adjustment elements (HVA)
• VANOS supply
• Camshaft bearings
• Overhead oil tubes for the valve gear
42-02-71 Crankcase with Oil Jets
1. Oil Jet for Drive Chain Cylinder Bank 5-8
2. Oil Jets for Piston Cooling
42-02-72
Oil Check Valves
1. Oil Check Valve for VANOS Intake
2. Oil Check Valve for VANOS Exhaust
3. Oil Check Valve for Cylinder Head Oil Supply
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N62 Engine
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Oil Pressure Switch
The oil pressure switch is located on the side in the bank 1-4 cylinder head.
Oil Pump
The oil pump is mounted at an angle to the crankshaft bearing cap and is driven by the
crankshaft using a roller chain. The oil pump is a two-stage gear oil pump with two paral-
lel switched gear clusters.
The two pair of gear clusters are stacked one
behind the other and work in two stages.
Stage two (both pump supply circuits) is only
active in the lower engine speed range up to
approx. 2,000 rpm to provide sufficient oil pres-
sure for the VANOS at high oil temperatures.
Stage two is deactivated hydraulically at a pres-
sure of 2 bar.
42-02-73
42-02-75
42-02-76 Oil Pump
1. Drive Shaft
2. Mounting Points
3. Oil Filter
4. Pressure Relief Valve (over 15 Bar)
5. Control Valve (Pump Stage/Pressure Control)
6. Oil supply from the oil pump to the engine
7. Oil pressure control tube from the engine to
the control valve.