Head gasket with a check valve

A head gasket which acts, when clamped between a head and a cylinder block of an internal combustion engine, to form a seal around at least one lubricant or hydraulic fluid passage which extends between the head and the block, wherein the gasket also comprises a non-return valve which is arranged so that, when the gasket is clamped as aforesaid, the valve extends across said passage and allows flow of liquid in said passage towards the head but prevents flow of liquid in said passage towards the block.