Mercury - Quicksilver Engine Gasket 4-Stroke 8-9.9HP Outboards 802699002. Overview. A good gasket might not look like much, but it's one of the unsung heroes inside your outboard. The Mercury Marine 802699002 Quicksilver Engine Gasket keeps your Mercury 8-9.9HP FourStroke carbureted (209cc) engine sealed tight so it runs smooth and clean. Built from heat-resistant, fuel-safe materials, this OEM gasket handles the constant pressure and vibration of marine use without shrinking or breaking down. I