BMW N55, Manual, Page: 14 / 100

Engine Housing
The engine housing consists of the engine block (crankcase and bedplate), cylinder
head, cylinder head cover, oil pan and gaskets.
Engine Block
The engine block is made from an aluminum die-casting and consists of the crankcase
with bedplate.
Crankcase and Bedplate
The crankcase features cast iron cylinder liners (2). A new feature is that the webs
between two cylinders on the deck of the block now have a grooved cooling passage
(3). Coolant can flow along these grooves from one side of the crankcase to the other,
thus enhancing cooling of this area.
Five oil return ducts on the exhaust side (4) now permit oil to return from the cylinder
head into the oil pan. These oil return channels extend into the bedplate up to below the
oil deflector. They help reduce churning losses as the returning engine oil can no longer
reach the crankshaft even at high transverse acceleration.
Five oil return channels on the intake side (5) also ensure that the blow-by gasses can
flow unobstructed from the crankshaft area into the cylinder head and to the crankcase
breather in the cylinder head cover.
The cooling duct (1) in the engine block is split and coolant flows directly through it.
Engine Components
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N55 Engine