help! - snapped bolt stuck in aluminium casting

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kashurst

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Help - bit of a disaster, I have managed to snap the head off a bolt whilst trying to undo it from an aluminium alloy cylinder head. Most of the bolt is still sticking out, Tried molegrips and heat but no luck. I don't want to take the head off and have it machined out unless absolutely necessary. Any suggestions gratefully received.
 
kashurst said:
Help - bit of a disaster, I have managed to snap the head off a bolt whilst trying to undo it from an aluminium alloy cylinder head. Most of the bolt is still sticking out, Tried molegrips and heat but no luck. I don't want to take the head off and have it machined out unless absolutely necessary. Any suggestions gratefully received.
Click to expand...

First off.
DON'T TRY EASYOUTS!!:(

Dunno the exact picture.
But I would have the 'bit' whats left cut, or whatever method 'flush'

If the bolt is ordinary mild steel (ie, not stainless or high tensile) one method is to drill a pilot hole into said stuck bit.
Then to increase the hole little by little very carefully until the remainder can be 'picked' out.

What size bolt are we talking about Kas?
 
Once steel and aluminium get married it does tend to be for life! However, you say you have a bit sticking out - can you get a lump of metal welded onto it and use that to undo the broken bit?

Easy-outs are a waste of time, in a stubborn bolt they either break or expand the bolt making things worse. Drilling out and re-tapping is the final resort if welding a lump of metal on does not work. It's all down to corrosion and the distance apart of these two different metals on the galvanic series table I'm afraid.
 
The bolt is an M8 thread. dont know if its high tensile steel - it holds the thermostat housing on (probably not in theory). Is an easyout the same as a thread extractor (left handed spiral thingy - usually snap off in an annoying hardened tool steel kind of way).

As the bolt isn't under a great load and not safety critical, I have wondered about welding a new bolt onto the end so have a stud instead of a bolt. what do you think ?
 
SIMPLY!! place a well fitting washer around the bit that is left then weld the washer to the broken stud(the washer prevents the surrounding metal from being damaged) and weld a bolt onto that. Then (whilst hot) gently work the thing loose. I don't know if you can get your hands on a welder but I have used this method a few times on bolts from M8 to M12 and it has not failed yet. It even gets them out when they are snapped off a few mill below the surface, but it is always a last resort. Oh and don't forget to unplug any ECU's or eletronics first.
 
if accessible.. file down two sides of the round stud flat and use a spanner to turn the stud... or if surround metal isn't going to crack, hammer on a socket head that has a slightly smaller diameter of the stud that's sticking out, heat up the socket and use a wrench to undo it
 
As the bolt isn't under a great load and not safety critical, I have wondered about welding a new bolt onto the end so have a stud instead of a bolt. what do you think ?

...........................................................................
Nowt wrong with that idea, but FCS dont melt the aluminium.
 
Had one snap removing the water pump in an outboard last week.
After removing the pump there was about half an inch still sticking out, plenty of heat from a blowlamp and a pair of stillsons did the trick.
 
Hi The welding route is a good one.If you have some of the bolt sticking out,you can get a snapped bolt removing kit (not easy out) it makes sure you drill it dead centre,so no mistakes running off centre. Try MachineMart
 
kashurst said:
The bolt is an M8 thread. dont know if its high tensile steel - it holds the thermostat housing on (probably not in theory). Is an easyout the same as a thread extractor (left handed spiral thingy - usually snap off in an annoying hardened tool steel kind of way).

As the bolt isn't under a great load and not safety critical, I have wondered about welding a new bolt onto the end so have a stud instead of a bolt. what do you think ?
Click to expand...

An easyout is a thread extracor yes, tapered, hardened, left handed thread jams in hole in broken bolt (in theory) to extract it. Works on studs/bolts snapped or sheared due to over torquing, not due to seizing caused by corrosion. Weld a new bolt to the old (use a washer to protect around the area) anbd get the old bolt out if you can. Due to the welding heat it may well loosen enough to extract it. Then get an M8 tap and clean the thread out. Converting to a stud could work if you could guarantee the weld would hold up - lazy sod! Take out the broken bit, I'm the only bodge-up artist allowed round here!
 
aquatom said:
SIMPLY!! place a well fitting washer around the bit that is left then weld the washer to the broken stud(the washer prevents the surrounding metal from being damaged) and weld a bolt onto that. Then (whilst hot) gently work the thing loose. I don't know if you can get your hands on a welder but I have used this method a few times on bolts from M8 to M12 and it has not failed yet. It even gets them out when they are snapped off a few mill below the surface, but it is always a last resort. Oh and don't forget to unplug any ECU's or eletronics first.
Click to expand...

As above but i weld a nut instead of a bolt. You can fill the centre of the nut with weld and you will find the heat alone will be enough without undue force on the spanner. The steel weld will not be hot enough to melt the ally.
 
I have been faced with this same problem many times and use a variation of some of the above:

1 clean the remains of the broken bolt with a wire brush
2 slip a washer over the busted bolt
3 weld the washer to the busted bolt
4 weld a nut to the washer
5 whilst hot beat a tight fitting socket onto the nut
6 work back and forth whilst hot

* welding the washer to the busted bolt increases the surface area and increases the amount of weld holding the nut to the busted bolt hence its less likely to spin off and snap the weld.

i probably have an 80% success rate using this method over the last 25 years so it well tried and tested !
 
Not knocking anyone else's method, but (unless it's impossible to get them on the bolt) using stillsons seems a lot easier and faster than all this welding.
 
Had a similar situation a few years ago with a Jag V12 engine and I tried all sorts of things. In the end I phoned a chap in Jaguar manaufacturing dept at Browns Lane and he gave me a dead easy way of doing it that'll cost you nothing.

Make a dam around the bolt using plasticine or Play Doh or something similar. Fill it with Wonder Wheels alloy wheel cleaner and leave it over night. Next day it'll come out dead easy. I thought exactly what you're thinking - yeah and my cocksakipper, but I tried it and it worked. He also said you can use Coca Cola instead of the WW, but it's not quite as good. But it has to be Coke, not Pepsi or any other brand. Dunno about that, but the WW worked a treat.

Go on, try it, what have you got to lose?
 
thanks for all the ideas. I welded a length of threaded stud onto the broken bolt. it all tightened up OK so fingers crossed. I will try the wonder wheels trick in future
 
kashurst said:
Help - bit of a disaster, I have managed to snap the head off a bolt whilst trying to undo it from an aluminium alloy cylinder head. Most of the bolt is still sticking out, Tried molegrips and heat but no luck. I don't want to take the head off and have it machined out unless absolutely necessary. Any suggestions gratefully received.
Click to expand...

My method with the nut above works even if the stud has broken on flush with the ally.
 
kashurst said:
Help - bit of a disaster, I have managed to snap the head off a bolt whilst trying to undo it from an aluminium alloy cylinder head. Most of the bolt is still sticking out, Tried molegrips and heat but no luck. I don't want to take the head off and have it machined out unless absolutely necessary. Any suggestions gratefully received.
Click to expand...

My method using a nut works even if the stud is snapped off flush.
 
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