That appears to be the brass threaded insert that is molded into the plastic intake which is used to bolt down things like your fuel rail, throttle body, and other brackets. I have identified those inserts in the picture I posted below with red circles on that PI intake. Your inserts may be positioned differently. Hope this helps, Tommy.
Excellent post Tommy. You have to be careful when screwing bolts into those brass fittings. They are only pressed into the composite manifold, so overtightening will cause the brass fitting to break free...and could also damage the manifold itself. Even if it doesn't damage the manifold, you won't be able to tighten the bolt. I have experience in this situation...I used 5 min epoxy to glue the brass piece into the hole, then gently tighten the bolt.
Yours looks like the manifold is cracked near that brass fitting..? Is that what we are seeing? That would certainly cause a serious vacuum leak!!!
The brass fitting DOES NOT need a bolt in it to seal. With or without a bolt, you should not have any vacuum leaks.
I see what you are talking about in the pic...I did NOT notice that when I took the shot...Hopefully its just a weird glare?? The car runs damn good to have a cracked manifold...let me run outside and check that.
If you think you may have a vacuum leak, what you need to do first is remove one by one, each vacuum line or hose which includes the rubber 90 degree elbows and check each part with a fine tooth comb. After you have removed any one of the parts, bend it to check for cracks. These hoses, elbows and plastic tubes don't last long with the engine heat. When I replaced my son's 2003 GT Mustang 4.6 intake manifold, I found 3 items that were cracked or broken in half, such as the rubber hoses, elbows and hoses. Make sure you check everyone of them, chances are you will find an item that needs to be replaced. Other than that, if your intake does indeed have a crack in it, or is leaking coolant somewhere, than that has to be checked out as well. Good luck, Tommy.
thank you for the suggestions, as there are no doubt a mess load of vaccum lines under there... good news, it is NOT a crack in the manifold, just a weird shot i guess...