Cylinder Block — Design Description (BMW X5 E53)

The cylinder block has thin-walled, cast-iron liners, made of grey cast iron, the liners of which can be repaired (bored). The angle of the engine cylinder block is 30°, to the right. The cylinders in the block are arranged in-line. In the lower part of the cylinder block - the crankcase, there are seven bearing seats for the crankshaft main bearing shells. The main bearing caps undergo final processing together with the block, so they are not interchangeable. In case of wear or minor damage, the cylinder surface can be restored by boring with subsequent honing in a service station, and installation of intermediate or repair size pistons. The design of the cylinder block is shown in Figure 6.2.

Engine Cylinder Block Parameters

Piston-cylinder clearance, mm

• nominal - 0.041 - 0.077
• maximum permissible - 0.15

Cylinder diameter, mm

• nominal -
• intermediate -
• 1st repair size -

Ovality of cylinder mirrors, mm

• nominal - 0.01
• permissible - 0.04

Permissible conicity of cylinder mirrors, mm

• nominal - 0.01
• permissible - 0.04

The permissible total clearance during wear between the piston and the cylinder is 0.15 mm

The diameter of the cylinders is measured with a bore gauge in three zones in mutually perpendicular directions, at a distance of 10 mm from the upper and lower edges and in its center.