broken stud, then extractor...can't remove reminisce

[scartail]

Hi,

 

I orginally posted in another subforum, but did not get any response. Figure I was posted in the wrong subforum.

 

There was a broken exhaust stud in the head. The break was recessed. I attempted to remove it with an extractor, and ended up breaking the extractor. I found website that described using a dremel and griding bit to grind through the extractor. I was able to do much of this. However, the reminisce of the stud/extractor still remains. To the best I could, I opened up the hole size for tapping M8. Still bits of steel remain. I used a magnet to detect the steel.

 

Then I found a website that reference using battery acid to eat away the steel. I did this over several days. Still no, luck. As you can see, I only get rust.

 

Any advice? I hope not to open up the hole further, then use an insert or helicoil. Someone out there must have a trick.

 

 

 

[rossman]

Pull the head and take it to a machine shop to remove and helicoil it.  Sometimes there's no way to get around it.

[ZHoob2004]

Iron bolts can be dissolved with alum (the spice). Never tried it, but seen it mentioned before for removing bolts from aluminum.

[LLave]

This situation can be a real pain. I have had pretty good luck taking a smaller fastener, grinding a bit of a point on it, then Tig welding it to the remainder of the broken fastener, then grab the new welded on part and twist out. The heat from the tig helps break it loose. 

 

Other than that. Stuck extractors suck big time. In car, without a really rigid drill (IE: milling machine), the drill bit hits the hard piece of extractor and wanders, making an even bigger mess. You may need to pull the head and take it to a pro. 

[scartail]

i bit the bullet and bought a thread repair kit.

 

it was a long shot to see if i could recover it.

 

thanks for the suggestions.

[twofouroh]

Heat helps a lot too, since aluminum expands faster than steel.  Everybody says alum (used for pickling) will dissolve steel w/out harming aluminum.  Dont forget to silicone the hell out of that thermo housing when you put it back on, they leak onto the studs all the time.  I run no gasket and Permatex Grey on mine, never leaks, but the metal has to be clean and flat.