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Author: Subject: Snapped spark plug in head
T66

posted on 30/5/13 at 09:20 AM Reply With Quote
Snapped spark plug in head

I knew the plugs were tight on the engine, and had just left it as another job to do eventually. Over the last few weeks I've been dosing them with releasing oil, so yesterday took them out.

3 were ok , but threads on 2 of them are shagged. No2 was tight all the way out. Once out it has parted company with the electrode and a portion of the plug thread tip, which remains in the head.

I had anticipated doing inserts on the 2 damaged threads, will the snapped plug end drill out ? My concern is getting it out then it not accepting a coil.

This is in the long term list of jobs to do...



Cheers.








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r1_pete

posted on 30/5/13 at 09:29 AM Reply With Quote
being hollow, it should drill out nicely, as you have a centre to work with.

If you are careful and increase the drill size in small increments, you can get to a stage where you can 'flake' the last bits away and save the thread.

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T66

posted on 30/5/13 at 09:41 AM Reply With Quote
quote:
Originally posted by r1_pete
being hollow, it should drill out nicely, as you have a centre to work with.

If you are careful and increase the drill size in small increments, you can get to a stage where you can 'flake' the last bits away and save the thread.





I like that, at least I can have a go myself without spending money. If I chose to coil insert them what is the job for ensuring they don't fall out. I've read about the wurth inserts, but they would need fitted from the spark plug entry hole side ? and access is hopeless.






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Aaron_n_Sim

posted on 30/5/13 at 09:44 AM Reply With Quote
Is the engine stripped? The part that's come away is not threaded is it and looks narrower than the thread part, I'd be more concerned it could be sat in the engine!





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T66

posted on 30/5/13 at 10:02 AM Reply With Quote
quote:
Originally posted by Aaron_n_Sim
Is the engine stripped? The part that's come away is not threaded is it and looks narrower than the thread part, I'd be more concerned it could be sat in the engine!




Not stripped, with careful angling of the head torch I can see the electrode still in the hole .. It's coming to bits anyway by the look of it lol.






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Aaron_n_Sim

posted on 30/5/13 at 10:07 AM Reply With Quote
quote:
Originally posted by T66
quote:
Originally posted by Aaron_n_Sim
Is the engine stripped? The part that's come away is not threaded is it and looks narrower than the thread part, I'd be more concerned it could be sat in the engine!




Not stripped, with careful angling of the head torch I can see the electrode still in the hole .. It's coming to bits anyway by the look of it lol.


You're gonna have to take the head off anyway, if you drill it you won't want the metal remnants in your cylinders.

Aaron





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Wheels244

posted on 30/5/13 at 10:13 AM Reply With Quote
Hi Ivan

If you get stuck I think my brother may be able to help - he owns a precision engineering company.

http://www.lowtonengineering.co.uk/default.html

He won't be able to do it for free, but I'm sure I could sort mates rates.

(p.s. this not a trade advert - just trying to help a forum member out - the link is just to show his machines )

We've made some quality one offs over the years for bikes and cars using his machines.

Rob

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britishtrident

posted on 30/5/13 at 10:29 AM Reply With Quote
Off with the head it will have to come off anyway.
It depends on the head design but is just possible it broken bit might come out by screwing it inwards.

Try carefully putting a drill through the same size as the root diameter of the male thread might remove the broken bit. If you get the bit out all you may need to do is run a thread chaser down it. A plug thread chaser can repair quite badly damaged threads because it pushes the threads back into shape more than a cutting action.


This is reminder to us all if we encounter any trouble removing or replacing plugs to run a plug thread chaser down the threads before replacing the plug.

The golden rule is if the plug won't screw in all the way by using just your fingers -- take the plug back out and chase the thread in the hole.

The two main causes of damaged threads are cross threading and the plug not sealing properly ie not tightened enough.

[Edited on 30/5/13 by britishtrident]





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T66

posted on 30/5/13 at 01:01 PM Reply With Quote
quote:
Originally posted by Wheels244
Hi Ivan

If you get stuck I think my brother may be able to help - he owns a precision engineering company.

http://www.lowtonengineering.co.uk/default.html

He won't be able to do it for free, but I'm sure I could sort mates rates.

(p.s. this not a trade advert - just trying to help a forum member out - the link is just to show his machines )

We've made some quality one offs over the years for bikes and cars using his machines.

Rob





Good replies thank you all.

The plan is to finish off the ancillary stuff, oil fuel brakes panelling then get the chassis powder coated, the engine & axle will then get some tlc while they are out.



Thanks Rob appreciate the assistance, will see how I get on first (knack it totally) and then seek the help of experts






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