Bought a beater '99 with a 3.0. Driver exhaust manifold gasket has a "port" that will not seal....what is this thing for and who has figured out how to keep this thing from leaking? Its the silver flap....pain in the butt

 

Haven't come across that before
I assume its not threaded under the "flap", like an EGR tube connection
Can you thread it?
And screw a plug into it

There are High Temp sealants made for exhaust manifold temps
Make sure "flap" is flat, pound it flat if not
If it has been over tightened it will bend so can't seal at the end away from the bolt

 

can't screw anything into it....not threaded.....time to get creative.