Drill out broken exhaust manifold stud- water/antifreeze!

Posted by Stephen Templeton On 2019/4/18 17:38:55

Per a previous post, I am re-porcelainizing my intake and exhaust manifolds. Unfortunately, one of the exhaust manifold studs was corroded and broke about 1/2 inch above the flush surface. I used lots of penetrating oil and heat but when I tried to remove it, it broke again about 1/4 inch inside the drilled stud hole. Today, I decided I would have to drill it out, so I started with a very narrow 1/16 bit and to my surprise, it drilled very easily and before I know it I was through the stud, but when I pulled the bit out antifreeze came shooting out through the hole I had drilled through the broken stud! I had noticed that the freeze plugs were located on the same horizontal level as the studs, so I guess it makes sense that the water channels communicate completely with the drilled exhaust stud holes. I've drained the water to a level below the holes, and I suppose I will continue to drill out the broken stud or try an easy out. Does anyone have any experience or words of wisdom with this. I don't think I can do any harm continuing to drill out the broken stud, but I'd appreciate any feedback from anyone who has more knowledge.

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