I just went to replace my valve cover gasket on my 2005 Ford Mustang and there was no rubber gasket on there.
Hey there. There is no known Ford Mustang engine I know of that does not have a gasket for the valve cover. Some engines will use a bead of silicone all the way around. You will need to clean out the groove on the valve cover and install with a new gasket. So depending on the engine you have in your Mustang, you will need to install a gasket or rubber seal when installing the valve cover.
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