SPARK PLUG hex broken

nGtim · Postby **nGtim** » Fri Dec 14, 2012 10:36 pm

Hi guys after I took ownership of my mx5
I hurried to get everything serviced and to make sure it was running alright.
One of the major issues I found was that 1 out of 4 of the spark plugs had the hex section broken off.
Now the other three were quite tight on as well.
Theres nothing to get a socket onto the spark plug. And there was signs of someone stressing about trying to remove it as well. ( Some silicone? NO idea why..)

Has anyone ever had this happen to their car?
What method was used to get it out?

So far a few people have advised that I may have to remove my head in order to get it out and even then risk damaging the thread in the cylinder. I'm hoping theres a much more efficient and cost effect method.

If anyone has anyone they can recommend or can share any experiences that would be much appreciated.
Moreover the engine is a 1.6L and has cams and some 'head work' supposedly.

Cheers
Tim.

Hjt · Postby **Hjt** » Fri Dec 14, 2012 10:42 pm

Theres nothing to get a socket onto the spark plug. And there was signs of someone stressing about trying to remove it as well. ( Some silicone? NO idea why..)

Are you using spark plug sockets to begin with?

nGtim · Postby **nGtim** » Fri Dec 14, 2012 11:00 pm

A spark plug socket was used yes for the other three spark plugs and all came out successfully..
However that specific cylinder had the spark plug hex section missing.
Might add that I didn't break the plug nor could I find any remains of the hex section.
Someone prior must have over tightened the spark plug causing it to break then removed all remains and hoped the car to never 'misfire'.

I really want to sort this out with the minimal (uni student) funds I have,
as I have drive the car around a lot and hope to taking the car out to the track more regularly.
Cheers.

manga_blue · Postby **manga_blue** » Fri Dec 14, 2012 11:17 pm

Clean out the hole and the plugs really well with throttle body cleaner. Blow it all dry. Pack a long spark plug socket with just enough araldite mix. Slide it over the plug and let it set for a day ....

It's easier if you remove the cam cover.

Steampunk · Postby **Steampunk** » Fri Dec 14, 2012 11:22 pm

It's difficult to imagine the hex sheared off leaving the rest of the plug in place. If anything I would think that the whole top half of the plug to snap off.
Off the top of my head, get different size socket that is the closest fit around where the hex was (try imperial sizes too), either use a blow-torch and heat up the socket and bang it as gently as you can around the hex. Leave it to cool in hopes that it's grabbed the plug as much as it can upon contraction.
You'll probably ruin the socket so use an old/cheap one.

Hopefully this does minimal damage so you can try multiple times.

If that fails, then snap off the insulator somehow, and try to use a set of ezy-out's with the utmost care.

Postby **NitroDann** » Fri Dec 14, 2012 11:49 pm

manga_blue wrote:Clean out the hole and the plugs really well with throttle body cleaner. Blow it all dry. Pack a long spark plug socket with just enough araldite mix. Slide it over the plug and let it set for a day ....

It's easier if you remove the cam cover.

zoomzoom · Postby **zoomzoom** » Sun Dec 16, 2012 9:41 pm

The standard BKR plugs have a very short and low hex section, most spark plug sockets have a bit of a tapered lead on the inside to make it easy to get the socket onto the plug, this often causes a very small engagement on the hex of the plug and especially in the case where the plugs are over tightened to begin with this results in the top of the hex being stripped. When I was using standard plugs I got a plug socket and ground the end of it so there was no lead in left to give the best possible engagement of the hex on the plug, this may be all that is needed. Aside from the longer life I get out of copper plugs in fairly trying conditions, the hex is longer and higher so this is not a problem anymore. For people wanting to look at these the NGK number is BCPR#ES-11 where # is the heat range the same as the BKR plug, na6/8 run different heat range, for for turbo I run BCPR7ES which is colder (in NGK the higher the number the cooler the plug) and without the -11 they come pregaped at 0.8 rather than 1.1.

Pic showing how much lead in there is on a normal plug socket next to the one I ground flat for the purpose.

rsz_p1030248.jpg

I don't have a pic of the std BKR plug but here is the BCPR, compare that to what you took out of the other cylinders you should see what I mean

rsz_p1030252.jpg

Sorry for being long winded, just trying to share some of my experiences to hopefully help others. Best of luck!

Cheers,

Tim