Broken spark plug advice

[GraemeVW]

Get a lot of this on saws and stationary engines, its normally corrosion between the plug and head, other times its carbon buildup on the exposed thread inside the cylinder head. Either way you tend lose the thread when undoing the spark plug, op`s head has the plug seized to the point the thing has sheared off completely, I wouldn't be holding out much hope on that one. As with all this stuff the remedy is quicker than beating the ideas about.

Bob

Installing inserts is as easy as this

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I've not seen those before, what a great idea!

 

[Pete.]

I've got one for 10mm plug threads. Have posted it out to people before now to get them out of bother. Some people see helicoiling in situ as risky heresy but as I have said before, most people drop more debris into the cylinder just by not blowing the plug wells out than you lose cutting a helicoil thread, and nastier stuff too. You can get most of the debris out with a hoover and small pipe as it will just sit on the piston crown right below the hole. Apart from that, aluminium melts a couple of hundred degrees below engine running temperature.

 

[DAPPH]

Lower the piston to 1/2 way & try a diamond point chisel ground on the side edges so it bites in if unscrewing , so if it's tapped into the hole /sleeve it bites enough for you to use a ring spanner to carefully & steadily apply pressure down the axis to turn the chisel and unscrew the threaded bit . Vacuum out any crud on a thinnish tube that goes down the hole easily .

 

[premmington]

@8ob

I have used the thread inserts - you were talking about - they a good solution.

Odd car plug that has gone south on me - on cars the plugs are so deep now - you got very little choice but to drill and fit a "timesert" type thing.

Ebay is full of these kits with taps - in all the sizes you could ever want!

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C90 plug port is facing the elements - a bit of anti sieze grease is a good idea! Never had an issue with plugs on them myself - it is the exhaust studs that I end fighting to the death!

 

[Keithmac]

For trying to extract it I would knock a splined tool into the head, the easy-outs expand the plug thread as you are going further in making it harder to remove.

Spline bit and some heat.

 

[winchman]

I have the splined tools the rigid set still won't move it

 

[Keithmac]

You could fit the other head in 1/2 an hour, there's not much to it.

 

[winchman]

I don't want to touch the exhaust studs

 

[cocker]

Had the same on my gsxr .
Plus gas , heat and the biggest easy out I could get in the hole .
And a good bit of luck !
I've kept the bits - they still make sweat every time I see them .

 

[Agroshield]

If you know the spark plug thread, you know the tapping drill size for that thread.

I am guessing the inside of the plug is concentric with the outside. Drill the plug out with a tapping drill if you feel lucky, 0.1mm smaller than a tapping drill if you do not. The rest should unravel. Magnet on a stick to hoover up the swarf.

 

[winchman]

Thanks for al your ideas, luckily I found a very good solution, some one made me a good offer so I sold it!