Genuine BMW Engine Valve Stem Seal Set - for M57N & M57N2 - 11349071732Part number 11342247171 11349071732 Engine Valve Stem Oil Seal Set A valve stem seal is a small rubber and plastic seal located at the top of the valve stem in an internal combustion engine. Its primary function is to prevent engine oil from leaking into the combustion chamber while allowing the valve to operate freely. The seal creates a barrier between the valve guide and the valve stem, controlling oil flow and ensuring that the engine operates