I have a 98 f150 with the 4.6 in and am in the process of replacing my exhaust manifold gasket. Of coarse 2 of the studs snapped flush with the engine and i am having trouble removing them. I have tried drilling them out and have gotten nowhere. I tried drilling with titanium bits, cobalt, cheap bits,reverse bits, you name it and have been at it all day with no success. Is there any special drill bit to use? I have been drilling and drilling with each type of bit and even tried sharpening the bits and cant get the stud to drill out enough to use an extractor. Any suggestions would be greatly appreciated.

 

I had 4 broken when I pulled my manifolds off. I let the truck sit for a couple days and sprayed AeroKroil and gave them a shock with a punch and hammer. When I started the job the studs that weren't broken came out easy and the broken ones once I drilled them out a bit came out pretty easy with a extractor.
You got to be patient and let the penetrating oil work. You don't have to hammer hard either just enough to shock the stud to break the corrosion. The Aerokroil does the rest.

Good Luck.