Exhaust cover stud broken into the head

pierodn · May 1, 2015

Hi All,
I have tight too much the right exhaust valve cover lower stud (n. 067582) and it is broken into the head!
How do I remove it?
That method is used in this case given that I do not want to disassemble the head?
If I have to re-thread the attachment which is the correct thread?
What is the tap to use?.
Thank you.
Piero

Danno · May 1, 2015

You need a stud extractor of the corect size. You chuck it up in a reversible drill and punch a starter dent in the broken stud. Put the drill in reverse and start drilling. At some point, the drill par of the extractor bit will bind and unthread the broken porton of the stud. No idea where to tell you to get the extractor, but over here any Sears hardware has them.

http://www.toolstop.co.uk/sealey-ak7228 ... 5pc-p56691

L.A.B. · May 1, 2015

pierodn said:
If I have to re-thread the attachment which is the correct thread?
What is the tap to use?.

= 1/4 - 20 Whitworth (BSW).

(This BSW stud/thread was never changed to 1/4 - 20 UNC as far as I know).

pierodn said:
How do I remove it?
That method is used in this case given that I do not want to disassemble the head?

http://blog.gieselman.com/post/Broken-b ... moval.aspx

xbacksideslider · May 1, 2015

May be difficult to get a drill motor and left hand drill to the correct angle.

Is there even a slight nub left?

If so, a propane torch applied to the head might expand it enough to free the stud, if there is anything to grab.

If that doesn't work easily, then a second idea is to spot weld any protrusion that might be left of the stud to the inside center of a nut.

Danno · May 1, 2015

xbacksideslider said:
May be difficult to get a drill motor and left hand drill to the correct angle.

For tight spaces, one of these is handy:

Hobot · May 1, 2015

I have used a reverse twist drill bit that bored in enough to grab and drill unscrewed it. I had welder stick a rod to the stud below surface and hold it heating a second or so in a mower, waited 10-20 seconds for stud heat to swell surrounds then backed it right out. If rust swollen stud or normal methods fail then can use Strong Inorganic acid like Nitric or Hydrochloric or Sulfuric to turns enough of the threads to mush to release and back out. Alu is untouched by this. Area is damned off for surrounds by melted candle wax and masking tape form.

EZouts are common brand of bolt extractors.
https://www.google.com/?gws_rd=ssl#q=ez+out

aceaceca · May 1, 2015

Before drilling the thing and ruining the hole try taking a sharp pointed punch and get close to the outer rim of the stud and tap ,tap ,tap at an angle of course. If you get lucky she will unwind and cme out.

john robert bould · May 2, 2015

The big problem is getting the extractor hole central down the the broken stud, this may help.......turn on a lathe a small sleeve approx 5/16 Od with an 3/16 hole ,the sleeve/bush should be a good fit in the cover hole. Pin the cover back onto the head with the other pin/nut and a bit of sealant [this helps to maintain the position],ensure the sleeved end is central to the old broken stud, This is now your drilling guide ,drill down with a 3/16 drill ,make sure the cover is not pushed to one side by the drill trying to wonder ,keep the drill central . use a left hand extractor after a little heat....its never failed for me. Hope you under stood that. and good luck.

pierodn · May 2, 2015

aceaceca said:
Before drilling the thing and ruining the hole try taking a sharp pointed punch and get close to the outer rim of the stud and tap ,tap ,tap at an angle of course. If you get lucky she will unwind and cme out.

Done as you said.
I was very lucky and the stud unscrewed and came out.
Ciao
Piero

pierodn · May 2, 2015

L.A.B. said:
pierodn said:

If I have to re-thread the attachment which is the correct thread?
What is the tap to use?.

Click to expand...

= 1/4 - 20 Whitworth (BSW).

(This BSW stud/thread was never changed to 1/4 - 20 UNC as far as I know).

pierodn said:

How do I remove it?
That method is used in this case given that I do not want to disassemble the head?

Click to expand...

http://blog.gieselman.com/post/Broken-b ... moval.aspx

Hi Les,
Very Good idea in the video, i will use to put out the unscrewed stud into the lower early triple tree.
Thank you.
Piero

Hobot · May 2, 2015

this thread got me looking at engine builder sites on stud tigthening to find they all reccomend only finger tight stud seating as long as its fully threaded in w/o bottoming out first, so unless locktited in they should all come out seemingly too easy. Does this finger tight stud advise apply to Commandos?

splatt · May 2, 2015

Hi Les,
Very Good idea in the video, i will use to put out the unscrewed stud into the lower early triple tree.
Thank you.
Piero[/quote]

Don't do the welding thing on studs in alloy unless you want the thread to melt in the aluminium locking the stud in

L.A.B. · May 2, 2015

splatt said:
Don't do the welding thing on studs in alloy unless you want the thread to melt in the aluminium locking the stud in

I've successfully used this method to remove broken studs and bolts from aluminium castings before, and the aluminium was completely unaffected.

Exhaust cover stud broken into the head

pierodn

Danno

L.A.B.

Moderator

xbacksideslider

Danno

Hobot

aceaceca

john robert bould

pierodn

pierodn

Hobot

splatt

L.A.B.

Moderator

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