10
N73B60 Engine - Diagnosis
Cylinder Heads
The two N73 cylinder heads are a new development from BMW and have been adapted to
the new direct injection system. The cylinder heads are equipped with Valvetronic valve
gear and Bi-VANOS. The inlet camshaft and the Valvetronic eccentric shaft are jointly guid-
ed by a bridge support.
The ports for the high pressure fuel injectors are located on the intake side. The engine is
equipped with a high pressure fuel pump for each cylinder head. Each cylinder head has
a bucket-tappet drive on the exhaust camshaft for the high pressure fuel pump.
The secondary air ducts for subsequent exhaust gas treatment are integrated in the cylin-
der heads. The cylinder heads are cooled by the “cross-flow” principle. The cylinder heads
are made from aluminum and are manufactured using gravity die-casting.
Cylinder Head Gaskets
The cylinder head gasket is a triple layer steel gasket with rubber coating. This gasket ver-
sion is already established in previous engines (N62).
The cylinder head bolts for the N73 engine are M10x160 necked-down “stretch” bolts.
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The lower part of the timing chain housing is bolted to the cylinder head using two M8x45
bolts (arrows above).
DCS00654
