snapped plug

[audi90]

Was removing spark plug from a 1956 convertible thats not seen the road since 1968,it has a factory replacement gold seal engine,anyhow the plug snapped and i tried to remove the rest with a torx bit but it too snapped,does anybody know what type of drill bit will drill out the torx bit,thanks Stevie

[bmcecosse]

Pretty much NOTHING will 'drill out' the torx bit! It will be very hard. When you say the plug snapped - you mean the metal part of the plug has sheared off - leaving part of it still in the head ? Not heard of that before - but it does sound like head off job to get access. Good soaking with Plus-Gas - and maybe some heat will help. But if there is nothing left to grip - it may have to be tackled from the combustion chamber side - or just fit another head!

[alzax3]

It might not work in this case, (and as already mentioned, you'll almost certainly have to take the head off as you'll never get all the fragments out of the cylinder) but they used to sell 'Freih Drills' (spelling was something like that) round all the shows - there'd be a guy with a pillar drill happily making holes if files, big engineering drills, bearing casings etc all day. They were some sort of titanium/cobalt tipped construction. (I've got a set in a cupboard and have never used them.... ) At a pinch (I discovered before I bought the set of genuine ones at a car boot) you can drill out most stupidly hard things with a standard masonary drill: you need to put a keen edge on the tip with a grinder (or with a diamond file/diamond stone) use a slow to moderate speed and fair amount of pressure - and keep it from overheating while you're running it (squirt of oil now and then) I've drilled through high speed steel metal-cutting saw blades quite happily with this trick!

[simmitc]

I expect that there are many intrigued people watching this, it's not something I've heard of before. Could you please post a picture of the offending plug. Thanks,

[alanworland]

I once sheared off a bolt in a suspension casting, took it to a toolmakers that I used to deal with and had the offending part 'spark eroded' a process carried out under oil where a tungsten electrode is fed automatically into the offending part which gradually erodes!
Parts can be saved with no need for re-tapping. Worth a try?

[bmcecosse]

But very expensive - and really not justified for a basic 948 engine cylinder head! These heads - and similar 998 Mini engine heads - are often given away free!

[alanworland]

But worth knowing - for future disasters!

[audi90]

well guys got the broken plug out using a combination of hammering in snap on torx bits to punch the broken bit in and then cleaned the remainder of the plug out with a snap on die grinder and then gently screwed a new plug in and out till the threads were clean,still going to have to take the head off to get the filings out of the chamber and whats left of the broken torx bits

[audi90]

well guys got the broken plug out using a combination of hammering in snap on torx bits to punch the broken bit in and then cleaned the remainder of the plug out with a snap on die grinder and then gently screwed a new plug in and out till the threads were clean,still going to have to take the head off to get the filings out of the chamber and whats left of the broken torx bits

[Mogwai]

You may be able to fish the bits out of the cylinder with one of those telescopic magnets they can be bent quite a lot before they snap. but for Peace of mind may be best to remove the head

[bmcecosse]

Yes -well - be sure to get ALL the little bits out - and the grindings! Better pull the piston on that bore - and clean the rings and grooves out properly. Would have been much easier to lift the head before all the 'butchery'! But - well done for perseverance!