Removing a broken exhaust stud

Started by denise 20352, March 26, 2006, 03:48:27 PM

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Eric # 21241

Ive had a similar problem with a head bolt broken flush with  block surface. I remember it well it was Saturday and I needed the engine fixed ASAP to drive the following day. Being a blacksmith /welder I knew cast iron (the block) doesnt burn with oxy acetylene yet the steel bolt) does,so I covered all the surrounding cylinders and torched it out! It was amazing all the threads were in perfect condition after running a tap throught them. I took a chance and it worked great!
The advantage to drilling is when drilling a hole it is next to impossible to drill straight and to get it absolutly centered therefore some of the threads a bound to (be dammaged. with a torch only the bolt melts out.

JIM CLC # 15000

04-06-06
ERIC, When I was tearing-down my FLAT-HEAD I rounded the head of a rod bolt. An older genterman came by one day to see what I was cussing-at, eh,doing. He told me to drill a hole thru the rod bolt and for some reason the bolt can be removed. Damn, eh, he was right. The bolt came-out and I was able to use the SOCKET that rounded-off the head.
Good Luck, Jim

Bruce Reynolds # 18992

Jim,

By drilling the hole through the bolt, you actually turned the bolt into as tube, and as you drilled it, the clamping tension relieved as the "tube" was able to stretch and this released the tension on the thread.   The hollow bolt was relieved of most of its in-built tension.

As you undo the head with the spanner, the tube can lengthen as it twists, thereby releasing the "shoulder" binding that can really hold a bolt from turning.

Bruce,
The Tassie Devil(le),
60 CDV

denise 20352


  You mean cast iron has a higher melting point than steel?

Eric 21241

Hi Jim,
Thats a good trick, maybe the heat from drilling loosens it up.
Thanks, Eric

Eric 21241

Hi Denise,
Its not the melting point difference, I think its since there is no carbon in iron and steel has carbon the steel cuts with oxygen  and cast iron doesnt.
Eric