Cylinder Block, Crank Drive
Cylinder Block
The cylinder block for the X 10 XE engine has two parts. The upper grey cast part contains the cylinder bores as usual and the upper crankshaft bearings. The new feature is the lower part - the cylinder block base plate. In the interests of weight reduction, it is made of aluminium. The cylinder block base plate is designed as a crankshaft bearing bridge with integrated bearings to hold the crankshaft. The strut-like design provides optimal crank drive rigidity, reducing vibration and thus making a major contribution to the engine's low vibration and noise concept.
Legend for illus. G 3108:
- Cylinder block upper part
- Cylinder block lower part (cylinder block base plate)
- Flange for oil filter housing
- Service aperture for crankshaft lock pin
- Code number, cylinder bore diameter
- Code number, crankshaft bearings
5.4.1 Cylinder Block
Piston with Con-Rod
The con-rod is not designed as a solid body, but as a rod with two bars to save weight. As well as reducing weight, this design also has a positive effect on the way the gas impact force is channelled onto the stroke bearing journal: the force is not channelled centrally along the solid con-rod as in conventional models, but down the sides into the bearings via the bars.
The X 10 XE has broken con-rods; this means that the broken surfaces of the con-rods and con-rod bearing caps form an individual fit.
5.4.2 Piston with Con-Rod
Crankshaft
The cast crankshaft is mounted on four bearings. The bolted pulse pick-up disc (1) determines the engine speed via the crankshaft pulse pick-up and transmits this information to the engine control unit.
In addition, the 1st crank web (1st cylinder) has a groove (2) for holding a lock pin. The lock pin is inserted into the crankshaft for all operations on the valve and crank drive. It ensures that the crankshaft remains in the 1st cylinder TDC position during repair work.
Legend for illus. G 3110:
- Pulse pick-up disc
- Groove for crankshaft lock pin
5.4.3 Crankshaft
Lock Engine in TDC
For the first time in a petrol engine, it is possible to lock both the crankshaft and the camshaft in the 1st cylinder TDC position. The special service tools can be inserted in the dedicated apertures after removing a closure cover in the cylinder block and the cylinder head cover.
Required special service tools:
- KM-954 Fixing gauge for camshaft phase sensor disc
- KM-953 Fixing gauge, camshaft in TDC
- KM-952 Lock pin, crankshaft in TDC
