Downloaded from www.Manualslib.com manuals search engine 35
N62 Engine
Chain Drive
The camshafts are driven by a toothed chain, one for each cylinder bank. The oil pump is
driven by a separate roller chain.
1. Sensor wheels for the camshaft position sensor, cylinder bank 1-4
2. Tensioner Rail, Cylinder 5-8
3. Chain Tensioner, Cylinder Bank 5-8
4. Sensor Wheel for the camshaft position sensor, cylinder bank 5-8
5. Upper timing chain guide with integrated oil jet
6. Guide rail
7. Sprocket for Oil Pump Drive
8. Timing case lower section
9. Tensioning rail, cylinder bank 1-4
10. Solenoid Valve, VANOS exhaust camshaft
11. Solenoid Valve, VANOS intake camshaft
12. Upper Timing Chain Cover
13. Chain Tensioner, Cylinder Bank 1-4
14. VANOS exhaust camshaft Bank 1-4
15. Upper Timing Chain guide with integrated oil jet
16. VANOS intake camshaft 1-4Chain Drive
43-02-50
Downloaded from www.Manualslib.com manuals search engine 40
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
Downloaded from www.Manualslib.com manuals search engine 41
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
