Okay, if drilling is your only option then you may as well know how to do it right. The main trick to releasing a stuck bolt with a drill it to make sure you drill all the way through the end of the bolt. This takes some feel and common sense so you don’t go to deep. This will relieve the pressure and allow the penetrating fluid to get at the threads from both ends. Take your time and stay straight and centered as if you wander out of the bolt into the threads your easy out will bite into the block and the bolt at the same time and it will break. The screw extractor should then remove it fairly easy. If not keep soaking it in penetrating fluid and be patient. If the extractor breaks you are only left with the torch method.

That is to take a cutting torch and blow it out of the hole. It takes guts and faith, as too much heat will destroy your project. You just heat the end of the bolt as quick as you can without heating the surrounding metal and hit the oxygen cutting lever and blow out the bolt like blowing dirt out of a hole with an air gun. Once started you can not stop and restart. You have to keep the cutting action going until the whole bolt is gone. You will need some good cutting goggles in order to stay in there and see what is going on. It will leave the whole pretty clean and not damage the threads. Then a tap will clean out the rest pretty easy. This is the last resort and in the hands of an amateur can ruin a lot of stuff. The muffler shop guys use this method all the time rather than have to take a head off to remove broken manifold bolts as they can’t get a drill down there anyway.

Make sure you check the threads before you send that metric tap in there as they should be SAE threads.

Good luck

 

I have the same problem in my bronco '93 with 5.8L EFI Engine.
I've seen different types of bolt extractors like "Spiral flute" , "Flat Flute", "drill-out", "screw-out" etc etc. Any advise which would be the best?.
In my case I found already one screw missing (broke before), I broke one myself and there is another "soon to be broken". The engine is in the car so I have limited access, I'm in the process of reemoving the radiators to gain front access but I would like to hit the nail in the head the first time. I know that the more methods you try and fail, the worst for the block.
If you want to see different extracting tools try:
http://www.bizrate.com and search for "screw extractor" in "hardware & tools"

 

That's the only way to go. You might try a left-handed drill bit. They usually do a good job of extracting bolts, and if it doesn't, well you just tap it when your done.

JJ

 

If it's in the cover and you can take it to some one, try that. You might get a little sympathy from some one who has been there before?? Ask the nearest dealership where they send their stuff they screw-up to? If there is any bolt left at all, you might be able to file some flat areas on it so you can get a wrench on it?? I've screwed up enough of these to know my talents lie somewhere else. I would never put a torch in my hand to try and remove a bolt. I applaud those that can!!
Where you at in TX? Where I am, the heat gets you in the day and the mosquitoes at night!!!!!

Chuck