Cylinder head for compression-ignition internal combustion engine

A cylinder head for a compression ignition internal combustion engine, wherein:

• (a) the cylinder head comprises a cast iron lower part which is to be fixed onto the cylinder block of said engine and which is formed to define walls delimiting both a cooling chamber through which engine coolant can flow, and a plurality of cavities providing for each of the cylinders of the engine a precombustion chamber, a seat for a fuel injector, and induction and discharge ducts,
• (b) the cylinder head further comprises an aluminium intermediate part mounted on said cast iron lower part, and an upper cap element of aluminium surmounting said intermediate part, the upper surface of the aluminium intermediate part being shaped to define a bath for lubricating oil and being provided with support means for rotatably supporting the camshaft of said engine,
• (c) said cast iron lower part and said aluminium intermediate part define between them a breather cavity which communicates with the outside and which when the cylinder head is mounted on said engine block is arranged to communicate with the space underlying the piston within each cylinder of the engine, so as to enable exhaust of air in said space as each piston travels towards its bottom dead centre position,
• (d) said aluminium intermediate part is formed to define a number of vertically-extending apertures which communicate at their lower ends with said breather cavity and which at their upper ends open out into the upper surface of the said intermediate part at a level above the bottom of said bath, said apertures serving to limit the level of lubricating oil within the bath, and
• (e) said cast iron lower part is formed to define bolt holes for the location of fixing bolts for securing the cast iron lower part to said engine block, said bolt holes lying within the external periphery of said intermediate part in alignment with respective ones of said apertures whereby access to said fixing bolts is possible without the need to remove the aluminium intermediate part from the cast iron lower part.