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Advice on broken thread in block
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traction39



Joined: 19 May 2009
Posts: 344
Location: South Wales

PostPosted: Wed Dec 14, 2016 5:28 pm    Post subject: Advice on broken thread in block Reply with quote

Thought I would ask the experts on this forum the way forward on this one.
My 1936 Light 12 has a broken stud that is firmly corroded into the block. (wet liners) as in the photo. I could attempt to drill out the thread, but what to do with the broken side? If there is enough metal, maybe drill the hole deeper and re-thread and not worry about the break. Get it stitched and re-drilled...what do you think?
Photo 1:
Overall view



Photo 2:
Close-up of broken thread and break at side of chamber.



Thanks for your ideas and suggestions.
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Citroen Light 15 1953, Light 12 1939,
Riley 9 Special 1932
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Farmer John



Joined: 18 Feb 2010
Posts: 126
Location: Manawatu NZ

PostPosted: Wed Dec 14, 2016 11:52 pm    Post subject: Citroen block Reply with quote

Oh dear, that is sad. Best fix is a replacement block. The engine really needs to come out anyway, it needs to go into a machine to drill that stud. The chances of getting it with a handheld drill are about one in a hundred. On a good day.
Toolmakers use a spark eroding machine which is the optimum in this case, there might be an engine machinist with one. That stud is rusted in enough to screw the stud off, that is about as difficult as they get.
Dealing with the missing metal is a whole other problem but only you can decide how to remedy that according to how much you want to spend, and what standard you work to.
The liners seem to be flush with the block, may be the photo, but if they do not protrude at least three thou the head gasket might not seal. Might need to pull the liners and re-shim them.
Whatever happens get some top of the line coolant. Go to a lorry or tractor dealer, they have the best stuff because they deal with motors that will not last without it. Would have prevented your troubles.
Hope you can find a replacement.
John
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47Jag



Joined: 26 Jun 2008
Posts: 1116
Location: Bothwell, Scotland

PostPosted: Thu Dec 15, 2016 12:58 am    Post subject: Reply with quote

This was posted on the Antique Auto Clob of America (AACA.ORG)

http://www.tfoye.com/MTE/brokenheadstud.htm

Might be worth a try.

Art
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peterwpg



Joined: 10 Apr 2008
Posts: 1926
Location: New Brunswick. Canada

PostPosted: Thu Dec 15, 2016 3:34 am    Post subject: Reply with quote

47Jag wrote:
This was posted on the Antique Auto Clob of America (AACA.ORG)
http://www.tfoye.com/MTE/brokenheadstud.htm
Might be worth a try.
Art


I have seen a similar thing done with broken studs on large water pumps. Sometimes a slight leak would cause the stud to rust and erode, so when loosing the nut, or sometimes a bolt, it would shear at the eroded part.

Instead of the washer/nut spanner/wrench, a piece of steel bar about 2ft long (2 x 1/2) or similar, with a hole that fitted tight over the stud (as per the washer), but with a large diameter countersink on the outer side to allow room for the welding rod (arc welding). The idea was to shock the stud via the steel bar bar, one person hitting the top of the stud, not too hard and the same time another hitting the steel bar, first in a tightening direction and then in the other. Heat was often applied to the pump casing a slight distance from the stud. Repeated clockwise and anti clockwise without being too greedy.
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ajlelectronics



Joined: 04 Oct 2010
Posts: 164
Location: Gloucester

PostPosted: Thu Dec 15, 2016 10:25 am    Post subject: Reply with quote

If you can afford it / find it, get it spark eroded. Otherwise I have had success by welding a large nut to the stud and then winding it out. If that fails, you can still fall back to spark erosion.
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winchman



Joined: 21 Feb 2014
Posts: 104
Location: Merseyside

PostPosted: Fri Dec 30, 2016 3:37 pm    Post subject: Reply with quote

ajlelectronics wrote:
If you can afford it / find it, get it spark eroded. Otherwise I have had success by welding a large nut to the stud and then winding it out. If that fails, you can still fall back to spark erosion.


I have had some good results with this set
https://www.ridgid.eu/gb/en/10-screw-extractor-set
I would talk to a local garage or engineering firm first who has had some experience of this sort of work.
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Paul fairall



Joined: 17 Nov 2016
Posts: 212
Location: North west Kent

PostPosted: Wed Feb 01, 2017 3:39 am    Post subject: Reply with quote

I don't see why you would need to use a spark eroder on a soft metal stud when it can be drilled carefully to almost the tapping size. I've only used a spark eroded on broken off taps. It needs clamping on a radial drill table and drilling accurately but looks in a very sorry state.
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16vmini



Joined: 13 Jan 2017
Posts: 9

PostPosted: Wed Feb 01, 2017 4:28 pm    Post subject: Reply with quote

either get it to machine shop and see what they can do ..

if i was doing it in my garage , get a big nut over it , get some really good weld onto it / both ... red hot .. get some heat into it ...

then let cool a bit and then try and undo slowly
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16vmini



Joined: 13 Jan 2017
Posts: 9

PostPosted: Fri Feb 03, 2017 10:12 am    Post subject: Reply with quote

just spoke to my dad , who had very similar problem on his Morris 8 block , luckily he has a big pillar drill , and drilled down stud dead centre , then opened drill hole to exact size of thread, then picked out thread bits with sharp pointer..

slow .. but worked
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52classic



Joined: 02 Oct 2008
Posts: 381
Location: Cardiff.

PostPosted: Thu Apr 27, 2017 5:09 pm    Post subject: Reply with quote

Had a similar problem with a manifold bolt on the Zodiac. Drilled it, tried an easy-out....... Snapped the easy-out!

We went for spark erosion and luckily found a machine shop in Ystrad Mynach.
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Bitumen Boy



Joined: 26 Jan 2012
Posts: 1007
Location: Above the snow line in old Monmouthshire

PostPosted: Thu Apr 27, 2017 8:33 pm    Post subject: Reply with quote

52classic wrote:
Had a similar problem with a manifold bolt on the Zodiac. Drilled it, tried an easy-out....... Snapped the easy-out!

We went for spark erosion and luckily found a machine shop in Ystrad Mynach.


I did that, with one of the downpipe studs on a Herald manifold. Easiest way out was to swap the whole manifold, think I still have the old one somewhere cluttering the place up... Rolling Eyes
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