What is a Water Outlet Gasket?
After removing the water neck, you are likely to find a gasket, or parts of a gasket, stuck to its mating surfaces. Old gasket material may be stuck to the engine as well. This gasket is the water neck gasket. It needs to be replaced every time you remove the water neck, either with a ready to use OEM-style gasket or a sealing product.
Be sure to verify compatibility with your vehicle using a workshop manual before using sealant to replace your water neck gasket. Some sealant-type products are ineffective for making gaskets, depending on the specific application.