lock BMW 745i 2003 E65 N62B44 Engine User Guide

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N62 Engine
Coolant Circuit
The coolant flow has been optimized allowing the engine to warm up as quickly as possi-
ble after a cold start as well as even and sufficient engine cooling while the engine is run-
ning. The cylinder heads are supplied with coolant in a cross-flow pattern. This ensures
more even temperature distribution to all cylinders. The cooling system ventilation has been
improved and is enhanced by using ventilation ports in the cylinder heads and in the radi-
ator. The air in the cooling system accumulates in the expansion tank. When a pressure of
2 bar is reached in the expansion tank, the air is bled out by the pressure relief valve in the
reservoir cap.
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The ventilation ports in the front of the cylinder heads provide quicker “self bleeding”
during a routine coolant exchange. The complex cooling system and the small ventilation
ports require that time should be allowed after the cooling system has been filled for the air
to escape.
Coolant flow in the Engine Block
The coolant flows from the water pump through the feed pipe (1) in the engine's V and to
the rear of the engine block. This area has a cast aluminum cover (see following illustration).
From the rear of the engine, the coolant flows to the external cylinder walls and from there
into the cylinder heads.
The coolant then flows from the cylinder heads into the engine block V and through the
return connection (3) to the thermostat housing. When the coolant is cold it flows from the
thermostat (closed) directly into the water pump and back to the engine (recirculating for
faster warm up).
When the engine reaches operating tempera-
ture (85 ºC-110 ºC), the thermostat opens the
entire cooling circuit to include the radiator.
42-02-57
Engine Block Coolant Flow
1. Coolant from the water pump through the feed pipe
to the rear of the engine.
2. Coolant from the cylinder walls to the thermostat
housing.
3. Return connection to water pump/thermostat.

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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
Leakage Restraint System in the Water Pump
The water pump has a leakage restraint system for the functional leakage from the pump
shaft piston ring type seal. The coolant which escapes through the pump shaft sliding ring
seal usually accumulates and evaporates through a hold in the leakage chamber (evapora-
tion area).
If the sliding ring seal is faulty, the leakage chamber fills
completely with coolant. Sliding ring seal leakages can
be detected by monitoring the fluid level in the leakage
chamber (inspection hole).
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In the past, fully functional water pumps were often replaced because the functional
sliding ring seal leakage which is necessary for water pump operation resulted in evapora-
tion residues being left on the external walls of the water pump.
The leakage restraint system has the advantage in that the coolant escaping from the slid-
ing ring seal (normal, functional leakage) evaporates without a trace and cannot be mis-
takenly identified as a water pump defect during visual inspections.
Timing Chain Cover Lower Section
The waterpump mounts to the lower section to
channel coolant to the engine block.
42-02-61 Water Pump
1. Impeller
2. Sliding Ring Seal
3. Leakage Chamber / Evaporation Space
4. Leakage Chamber Cover
5. Delivery from the sliding ring seal to the leakage chamber
6. Hub of pulley and viscous clutch
Timing Chain Cover Lower Section
1. Coolant to Engine
2. Rear Water Pump Housing in Lower Section
3. Mount for Drive Belt Tensioner Pulley
4. Crankshaft Radial Seal
42-02-62

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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
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
Oil Filter
The canister type oil filter (3) is located under the
engine by the oil sump. The support for the oil
filter is integrated in the rear oil pump cover.
The oil filter housing (2 with o-ring) is threaded
into the rear of the oil pump cover through an
opening in the oil sump.
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The filter element support dome contains an over pressure relief valve. If the filter element
is blocked, this valve bypasses unfiltered engine oil around the element to the supply lubri-
cation to the engine.
Pressure Control
The oil pressure control valve in the oil pump has two functions:
1. Deactivates stage two oil pump circuit above 2 bar. Stage two is only active in the
lower speed range. This is to ensure that there is always sufficient oil pressure for
the VANOS units even at high oil temperatures and low speeds. The oil pump power
consumption is reduced by deactivating stage two.
2. Monitoring the required oil pressure for the engine. The piston in the control valve is
moved by a spring against the engine control pressure which is returning from the
engine. This means that precise monitoring of the actual engine oil pressure is pos-
sible.
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42-02-77