Mercury - Exhaust Manifold Gasket Engine Sealing Series Composite Marine Gasket 8M0162486. Overview. If you've spent years working on MerCruiser engines, there's a certain comfort in the parts that just fit right. No wrestling, no guessing, no hoping the seal will hold once the engine heats up. A good manifold gasket gives you that sense of reassurance - the kind you feel when the engine fires up and settles into a smooth, confident rumble. That's exactly what you get with Mercury Marine part 8M