I just went through this on my TR4A. You *can* get the remains of the
stud out without removing the head. You will need:
1. patience
2. dremel tool with small grinder bit (carbide is best)
3. patience
4. heat wrench (propane or MAPP torch)
5. patience
6. reversible drill
7. patience
8. collection of ez-outs and left handed drill bits to match, plus drill stops
9. patience
10. a drilling template
11. patience
12. a properly sized tap
13. patience
14. a little luck
The starting trick is to get a hole drilled into the center of the
stud. This is the point of the drill template - I made mine by copying
the holes in a manifold gasket. Make the hole you're going to drill
just larger than your starting drill bit size - I usually start at 1/8
and work up, but it will depend on what left handed bits you can find.
You can make the template out of plywood; aluminum plate is better. You
want adequate thickness to make sure that the drill bit is at an exact
right angle to the manifold face.
Drill. Use the drill stops! You don't want to drill deeper than the
stud (since it's an MG with a cast iron head, you probably won't be
able to do any damage, but be safe). Chances are that you won't get the
hole dead center, because manifold gaskets aren't made perfectly; do
the best you can. Go up in size until you are in danger of cutting into
the threads in the head; inspect often with a mirror and flashlight
(tip: point the flashlight into the mirror).
Use the EZ out. There are two sorts - straight fluted and twist fluted. I prefer
the straight ones, because all the force is used to turn the broken stud, rather
than twisting the EZout in farther. But the twist ones are more amenable to
weird hole sizes. Chances are that you won't get anywhere with the EZ out, but
try it anyway. Don't break it off, whatver you do.
Heat the area with the heat wrench, spray on some Kroil or WD-40, and wait.
Repeat several times. This might help, it might not. Try the EZout
again. Repeat until you're frustrated and ready to go on to the next
step, or, if you're terribly lucky, the blasted thing comes out.
Using mirror, flashlight and dremel tool, grind outward from the hole you've
drilled. Eventually, you will start to see the ridges of the thread cut into the
head poke through the stud material.
When you have achieved this state, you can start using the tap to remove the
remaining metal. Best is a tap with a tapered start, so you can get some
purchase in the hole you've drilled; once you've removed a bunch of the metal,
you can switch to a plug-style or bottoming tap to clean out the deeper grooves.
Chances are that the trapped material will break off in complete rings, which
you want to remove - pull the tap and use a sharp object to try to clear these
out before tapping more. You want to reverse the tap often in order to clear the
shards.
I spent three or four evenings in the process of removing a broken stud from
Sarah's head. It was not pleasant, but it beat the hassle and expense of
removing the head.
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