Spark plug stuck / cross-threaded

[gabriel_gs]

Am about to totally lose it.

Bike's been running a bit rough so bought a new set of spark plugs 1150gs twin spark)

Bottom ones changed fine, left main spark changed fine, then went to remove the right main spark and it's obviously been cross threaded - socket is moving at an angle as it rotates.

I can't undo more than 3 or 4 turns... Then 'snap!' - that'll be my screwdriver snapped then, through the top of the spark removal socket.

What the hell do I do now? It's stuck fast.

I'm imagining a VERY expensive engine part-removal to drill the bugger out??? Could cost a small fortune because of a bloody spark plug!?!

Help... Please!

 

[MikeO]

Can you get the snapped screwdriver out? If so, wind it back in a little and then remove the tool. Take off the rocker cover which will give you better access and a better angle...

 

[autogs]

2 options,keep undoing till snaps and then drill and helicoil,remove head and drill mill it out.i have number of a guy who is very very good at mobile removing of snapped diesel injectors etc who would make short work of this i reckon.he works the surrey area as well.ps his number is at work and i cant remember the company name,google thread repair in surrey and it will come up,his name is very unusual,do not use a firm called" crackers"if it comes up.feel free to pm me if you like
ps it may just come out without snapping.

 

[gabriel_gs]

Mike - the screwdriver was only being used as a 'handle' to turn the spark-plug socket (the one that comes in the GS toolkit), and the socket goes in and out freely, so the only issue is the stuck spark plug... and a snapped screwdriver


Autogs - yes please mate if can have his number

The last cross-threaded bolt on my bike ended up costing me nearly £500 to rectify, which is why I'm spitting chips about this.

Thanks chaps.

 

[The Grey One]

If the plug has been cross threaded you should be able to get it out with a good quality plug socket. Once out Würth make the tools for the repair, called Time sert. http://www.wurth.co.uk/hand-tools/thread-repair-and-reinforcement/thread-repair-system-time-sert The kit allows you to cut a new oversized thread and then fit an insert. This is a better option than a Helicoil which , in my opinion would be fine for something like a stud which once refitted dos not need to be undone again The Würth inserts are designed for the job and if fitted correctly will not come out when the plug is next changed. I have fitted literally hundreds into ally heads and have never had to remove the head to do so. Find someone who has this kit and it is a simply job.

John

 

[MikeO]

Mike - the screwdriver was only being used as a 'handle' to turn the spark-plug socket (the one that comes in the GS toolkit), and the socket goes in and out freely, so the only issue is the stuck spark plug... and a snapped screwdriver

Have you taken the rocker cover off to get a better look at it?

 

[Timolgra]

If you can, try getting the engine really hot and give it another go.

 

[gabriel_gs]

If the plug has been cross threaded you should be able to get it out with a good quality plug socket. Once out Würth make the tools for the repair, called Time sert. http://www.wurth.co.uk/hand-tools/thread-repair-and-reinforcement/thread-repair-system-time-sert The kit allows you to cut a new oversized thread and then fit an insert. This is a better option than a Helicoil which , in my opinion would be fine for something like a stud which once refitted dos not need to be undone again The Würth inserts are designed for the job and if fitted correctly will not come out when the plug is next changed. I have fitted literally hundreds into ally heads and have never had to remove the head to do so. Find someone who has this kit and it is a simply job.

John

Cheers John - if/when I get it out, I'll look into it!

 

[gabriel_gs]

Timolgra - Yep, I'll give that a go, hopefully tomorrow.

 

[gabriel_gs]

Mike, yeah already tried that, but it didn't help.

 

[gabriel_gs]

Timolgra.... Tried running the engine to hot... Still won't budge

 

[gabriel_gs]

Am gonna try john's thread guy.

My worry is won't cutting a new thread 'in-situ' risk getting metal shavings in the cylinder?

 

[Timolgra]

Am gonna try john's thread guy.

My worry is won't cutting a new thread 'in-situ' risk getting metal shavings in the cylinder?

Use a very sticky grease and clean the tap regularly

 

[DrFarkoff]

I cant understand how anyone could manage to cross thread one of those in fact any of the boxers

Have you tried a tapping solidly through the plug socket, pullbar bar whilst pulling the bar with a steady force? Also apply loads of something like AC 90 or my favourite "Break Away"

You may need an extra pair of hands

 

[gabriel_gs]

My brother is coming over tomorrow so I might try that.

I tried to use my socket set but it was too 'fat' to get down through the rocker cover - I didn't try my socket at the time, but I assume if I take the rocker cover off again, I should be able to get my socket to the spark plug - then I can get some proper leverage.

I assume a few sharp taps with a hammer on the end of the socket won't hurt either.

 

[gabriel_gs]

I guess if the worst comes to the worst it's a new cylinder head (£180 used from Motorworks) and a trip to Putney to have it all fit

 

[JayC]

Gabriel - do this job once, and do it properly!

I would suggest against thread re-tapping in situ because the thread is already crossed. Whilst a spiral fluted tap will only draw swarf upwards, as opposed to a spiral pointed tap pushing swarf forward, it can't draw upwards the existing damaged alloy where the thread has been crossed. The very fact it has been crossed means there is already loose alloy, either being held temporarily captive by the broken plug, or already dropped down into where you don't want it to live since you've disturbed it.

Don't take the chance, it really isn't worth it. Whip the part off and check for any loose debris and have the thread opened up, as suggest above, and repair with the insert.

Correction vs Consequences

 

[The Grey One]

Am gonna try john's thread guy.

My worry is won't cutting a new thread 'in-situ' risk getting metal shavings in the cylinder?

As has been pointed out use plenty of grease on the tap. Then spin the engine over on the starter with all the plugs out to blow out what might be left behind. Any tiny shavings left wont cause a problem with an alloy head. I never had any problems with fitting these inserts in situ and as I said I fitted hundreds over a 30 year period.

John

 

[warmshed]

My Bet is you will succeed in getting the plug out once you have a solid socket and direct force from a good size lever.
Use a dab of antiseieze grease in the future and torque up the plug rather than by guesswork.

 

[AdrianS]

Debateable if antiseize grease should be used on plugs.
NGK released a technical leaflet saying specifically that anti seize must not be used with new plugs with a shiny silver coating as this coating is designed to prevent
the plug from seizing. They also said the use of any lubricant would result in the plugs being torqued up to a higher value than specified with the potential for thread damage.