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Posted by Up North on May 14, 2007, 12:13 pm
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>> > > We just acquired a VW diesel rabbit for $400. The intake manifold
>> > > fell off after all four of its mounting bolts broke.
>>
>> > > One of these broke off sufficiently above the machined side of the
>> > > head that we were able to turn it out by striking the burr with a
>> > > chisel.
>>
>> > > However, the other three are broken slightly beneath the surface.
>>
>> > > Ideally, we'd like to remove these without having to remove the
>> > > Indian .. er.. engine...
>>
>> > > I am wondering about the possibility of striking an arc on the end of
>> > > each bolt and building this up until it's above the surface and then
>> > > turning 'em out with a chisel as we did the first one.
>>
>> > > Some time ago I read about a trick like this where the guy strick the
>> > > arc inside a small piece of copper tubing placed into the hole.
>> > > However, I presume that in his case he was working with a steel bolt
>> > > inside a steel head and that the purpose of the copper tubing was to
>> > > keep from welding the stud to the head.
>>
>> > > So the plan is to use some reasonably small rod at a suitably low
>> > > amperage WITHOUT the copper tubing. As I perceive things the
>> > > aluminum
>> > > will not melt because it is a better conductor of heat than the
>> > > steel.
>>
>> > CAUTION, I think this is FALSE, very false, if the arc contacts the
>> > aluminum
>> > I think you will find it melts easily and may make your problem worse.
>>
>> > > However, in my mind everything is easy. It's at the "reality
>> > > interface" that things start to go wrong.
>>
>> > > So, is this a viable plan? And if so, what rod flavor and diameter
>> > > would YOU recommend.
>>
>> > I like 3/32 (or maybe 5/64) - 6010, YMMV
>>
>> > > All answers appreciated. Correct answers REALLY appreciated. Plan
>> > > "b" is to remove the engine and drill 'em out.
>>
>> > > There is just enough room between the work area and the firewall to
>> > > make this doable if I bend the rod into an "L" shape.
>>
>> > Note comments below regarding welding by sound.
>>
>> > > Thanks!
>>
>> > > Vernon
>>
>> > This is a question that comes up frequently.
>>
>> > The standard answer is to weld a nut on the end of the broken stud or
>> > bolt.
>> > This is not always an easy job as it is difficult to align the nut to
>> > the
>> > broken stud and to make a good weld inside. The more experienced
>> > answer is
>> > to first weld on a washer with a hole slightly smaller than the broken
>> > bolt.
>> > I always keep a selection of thicker washers of various sizes on my rig
>> > for
>> > this purpose. Let the weld cool and clean the flux, THEN weld a nut to
>> > the
>> > washer, the nut can now be a lot larger and is easier to weld inside
>> > (or
>> > outside) and there is less danger of welding to the part you are trying
>> > to
>> > save. The shrinkage resulting from the cooling of the welds will help
>> > to
>> > loosen the stud, always allow to cool completely before torquing on it
>> > .
>> > This technique works well when the stud is not broken too far below the
>> > surface. It may require more than one attempt.
>>
>> > The following is from an earlier thread, subject 'here's a tough one,
>> > trying
>> > to remove a countersunk bolt'
>>
>> > > My suggestion is to make a piece of sheet metal and hammer it to a
>> > > little
>> > > cone shape with a hole at the apex of the cone large enough for the
>> > > bolt
>> > > fragment to stick through, and drop this cone, apex down, over the
>> > > bolt
>> > > fragment inside the recess. Then weld the bolt to the sheet metal,
>> > > then
>> > > take a nut and weld it to the sheet metal and turn the nut. This
>> > > trick is
>> > > what the old truck guys do, and it's what everyone should try BEFORE
>> > > you
>> > > go get the Vise-Grips and break off the end of the bolt fragment.
>>
>> > > GWE
>>
>> > also from the earlier thread, subject 'here's a tough one, trying to
>> > remove
>> > a countersunk bolt'
>>
>> > > Private wrote:
>> > >> For a small bolt like this I would suggest that the reverse drills
>> > >> would
>> > >> be a good first thing to try.
>>
>> > >> A similar technique to the sheet metal cone that I have had some
>> > >> success
>> > >> with is to take a piece of pipe that will fit inside the hole and to
>> > >> grind the end to be a good fit to the contour of the broken bolt.
>>
>> > Note that this is a steel NOT copper pipe.
>>
>> > >>You
>> > >> can then use a small stick electrode to reach down inside the pipe
>> > >> and
>> > >> weld the pipe to the broken bolt. You will not be able to see much
>> > >> and
>> > >> need to make the weld by sound, it helps to turn up the heat to
>> > >> avoid
>> > >> sticking. Don't burn through the side of the pipe. You should try
>> > >> a few
>> > >> practice welds inside a similar pipe. This technique is definitely
>> > >> easier on larger sizes but I has worked for me on some very deep
>> > >> problems.
>>
>> > When this works properly it is great, but use CAUTION, a failure can
>> > make
>> > the problem a LOT worse, (don't ask, but I do own one very expensive
>> > carbide
>> > drill bit!).
>>
>> > Good luck, YMMV- Hide quoted text -
>>
>> > - Show quoted text -
>>
>> Private,
>>
>> Thanks for elaborating and expanding on the concept. I really like
>> the "pipe trick". But here I'm dealing with the metric equivalent of
>> probably a 1/4" diameter hole. Nevertheless, the washer and/or
>> inverted cone concept definitely resonates.
>>
>> Vernon- Hide quoted text -
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>> - Show quoted text -
>
> This is the best group in the galaxy!
>
> Vernon
>
A reverse rotation drill bit works well in most cases but I have used a
piece of 1/8" X 1" X 2" long strap bent in an L shape with an appropriate
size hole drilled in one end instead of a nut to weld to the stud. It is
fairly easy to align with the broken stud and the L shape allows you to use
a vicegrip or crescent wrench to turn out the stud after welding. I always
use a slight rocking motion with application of penetrating oil to break the
stud loose before attempting turning it out.
Good luck
Steve
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