Single cylinder heads are used throughout the range of VM 3, 4, 5 and 6 cylinder water cooled engines. Employing this design reduces the amount of flexing and distortion the cylinder head is subject to by thermal forces when clamped rigidly to the cylinder block and thereby reduces cylinder head cracking. The use of single cylinder heads also allows more even clamping pressures to be exerted onto the cylinder head gasket. Changes to coolant passages were made to improve cooling and reduce cracking in hotspot areas which in turn reduced the likelihood of cooling system pressurisation. Multi layered steel head gaskets were also a vast improvement over the fibrous type.