Broken spark plug

[vmaximus]

Evening chaps, I have a bit of a dilemma, I have broken a spark plug in a spare motor bike engine. The engine has been stood for quite a few years and I was removing the plugs to turn the engine by hand. 3 plugs came out although a bit tight but the forth one had seized and would not move at all, after several attempts trying back and forth it eventually sheared flush with the head, is there a way of getting this plug out without having to take the head of which I prefer not to do, I have tried drilling a small hole so I can try to get a bit of heat on it but my bits don't seem to touch the centre of the plug. I do have some thread chasers so I can clean the remaining thread out when its removed. Thanks in advance for any info.

 

[Eric the chicken]

I understand your reluctance to take the head off. I'd feel the same, but even if you do manage to remove the broken plug without removing the head you'll almost certainly end up with all sorts of swarf etc in the cylinder. I think you'll have to bite the bullet and remove the head. Also depends how much you need the spare engine to be ready for use.

Eric

 

[Ruffian]

Is it anything special or not.
I would fill the bore right to the top with a releasing agent and break the electrode/ceramic into the bore, and risk a torx or multi spline in to release the rest,
(Even if needs a slit with a hacksaw blade)

Done previously with a yamaha fazer.
Got most of the metal out with a magnet and then
Let the rest bounce the electrode round for a minute until it fired out the exhaust though.

 

[vmaximus]

thanks for the reply's, I've knocked some of the ceramic out and filled round the plug with ATF/acetone mix, I'm going to leave it till tomorrow then have another look, Eric I don't need the engine yet but I was just doing a bit cleaning and messing when I broke the plug but I must say that it was/is very tight, never mind always another day.

 

[Robotstar5]

There's a good chance if you get it moving it will strip the thread in the head been there, done that.

 

[Ruffian]

There's a good chance if you get it moving it will strip the thread in the head been there, done that.

And that's why time serts are brilliant.
Makes even the worst sort of repairable.

 

[mcostello]

Is this small enough to work on it upside down, gravity might help?

 

[winchman]

I assume its a steel spark plug in an alloy head?
I have heard this is excellent
https://www.amazon.co.uk/Mouse-Milk-Penetrating-Oil/dp/B0049C7170
Have you a photo?
I wonder if these would be of use?
https://www.ridgid.com/my/en/pipe-extractors
Mine have been a life saver on a few occasions

 

[MattF]

At that price, the stuff ought be performng miracles.

 

[The_Yellow_Ardvark]

If your atf mix does not work try this.

This is bit dangerous, but does work.

You will need a cooker.
Old source pan.
Old engine oil 75%.
Diesel.15%.
Paraffin. 10%.


Heat up and pour down the hole. Walk away then come back in a day and try again.

 

[slim_boy_fat]

I wasn't sure whether to like that or not. Sounds full of potential as TYA says, but needs must......

Hands up anyone who has never done anything with potential for death or injury....

 

[angellonewolf]

I wasn't sure whether to like that or not. Sounds full of potential as TYA says, but needs must......

Hands up anyone who has never done anything with potential for death or injury....

me no never, never had to clean a mower fuel tank out before welding empyed the fuel tank did not realise ther is a lip around the filling hole add when i tiped it out i was throwing it around so the fuel was all over the fuel tank and lit it poped went up in flames and did defo not burn my eye brows and face hair

 

[vmaximus]

Thank you all for your reply's, I managed to put a hole through the centre of the broken plug with a bit of a sharp pointy thing then drill successively larger holes to the point where I can try to cut new threads with a 12mm thread chaser. This idea started to work but the chaser isn't quite hard enough to cut clean threads, I did try to get small amount of s/plug out with a easy out but it wouldn't budge, what I'm going to have to do is run through with a M12 x 1.25 tap (I hope this is the correct size), please correct me if I am wrong then it should be ok. Next will be getting the crap out of the cylinder. Thanks all.

 

[Robotstar5]

M12 plugs use a 1.25mm pitch so you're good to go

 

[vmaximus]

Thank you, just ordered one.