Anyone ever break a head stud?, Looking for ideas, tools success stories, horror stories, what cha got Options

[rick 918-S]

I'm building a 928 hybrid engine which is comprised of a 5.0L 32 valve short block with 16 valve euro spec "S" heads, spyder and CIS from the 4.7L "S" engine.

I stole some time from my busy work schedule to prep my 928 block for the machine shop. The head studs need to be removed for the boring process.

Now I've pulled studs before without incedent. But as Murphy would have it, this time I broke one of the studs flush at the start of the threads.

So I have the threaded section ( 1 1/4"long ) hardened head bolt stuck in the block. Normally this wouldn't be a problem, but the stud is free standing in a 3 1/2" deep hole in the block!

Here's a crude drawing of the problem I'm faced with.



Here's the stud.



Here's the stark reality of the stud in and out of the block. The stud slides down a 3 1/2" deep hole in the block before it starts to thread in.




I'm going to make a drill collet as a guide for a pilot bit. The problem is I need a long, reverse twist drill bit.

Most drill bits are approx 5" long. the hole is 3 1/2", the threaded section is 1 1/4" for a total of 4 3/4". See the problem?

Then, what the #$!! do you drill a hardened bolt with?

Anyone know of a good tool source? This is beyond most Mac and Snap on stuff I would think.

[Wilhelm]

I've had luck getting a stud out of a deep hole by slipping a tube down the hole with its bore roughly the same size of the stud. Then I feed down a 7014 rod and then arc weld the tube to the bolt letting it all cool. Fill the hole around the pipe with diesel for a few days so it can penetrate the thread. Heat the block in the area where the threads are locked and now try to wind out this mess.
Good luck!!!

[rick 918-S]

I've had luck getting a stud out of a deep hole by slipping a tube down the hole with its bore roughly the same size of the stud. Then I feed down a 7014 rod and then arc weld the tube to the bolt letting it all cool. Fill the hole around the pipe with diesel for a few days so it can penetrate the thread. Heat the block in the area where the threads are locked and now try to wind out this mess.
Good luck!!!

That's a great suggestion! (IMG:style_emoticons/default/aktion035.gif) That's the first doable idea I've heard for a stud in a deep hole. I've welded washers to flush broken bolts before, then welded a nut to the washer and backed out the bolt, but I've never seen a broken stud in a deep hole before. I may need to try this one.