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Help! Rounded spark plug!


New Member
July 6, 2011
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96 Explorer XLT 240k mile
Hi Serious Exploration People. Please help.

I have commited a sin, serious mistake, or bone-headed move. In an attempt to change a spark plug I have totally rounded the the thing. I didn't realize how rusted-on and siezed the thing was when I first gave it a try and now I'm in this situation.

I have been drenching the spark plug with PB Blaster.
I tried using a rubber band around the plug to fill the gap and make it sticky.
I have chipped away a good amount of rust that had fused to the spark plug, but still can't see a gap all the way around it.
The porcelain is broken, most all of it gone now.
I can't just drill it through the center like some silly 'ol bolt, can I?

ANY ideas will be welcome.
Please help.
Thanks, Ken

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It seems like it could work. You must make sure you do not leave and pieces parts in the cylinder or you may have bigger problem down the road.

It is something I would try.

If you can get at it with a hammer, try hammering the "next size smaller" metric socket onto what's left of the plug.

You could also try an ez-out.

IMO, drilling would be a last resort - if any chunks are left in the cylinder it could be a big problem. I'd think long and hard about pulling the head first.

Before you go drilling anything with the possibility of getting metal & porcelin bits into the cylinder, try a better fitting 6-point socket with a breaker bar. Since the plug is shorter now you can get a regular socket on there. Tap it in place with a hammer to get it good and tight. The tapping will also help with the rust. Get lined up straight and it should turn out. Most of the broken ones I've seen are from having a socket not completely seated on the plug and slipping sideways. Depending on which cylinder it is, I would suggest you get the tire and splashguard out of the way and work from the wheelwell so you can apply the torque straight.

Edit: BubbaFL beat me to it!

Check this page of posts out...


Do not drill them out, unless you have the head off. Even then, you will have to clean the threads. A delicate job on aluminium heads. Easy out is the way to go if the porcelin is already broke. If the "nut" isn't completely rounded the above ideas are good too. You might also try a gator driver. Whatever you try, make sure you can get on the plug straight. Deffinatly remove the tire and splash gaurd as needed.

I have never tried this on a plug but on other "stubborn" bolts. Take a plug out from another cylinder.... no reason but this is your "check nut size". With that plug out, take a good look at your socket and spark plug "nut" to see how well (or not) the thing fits. Next grab the next size down socket. Check it on your "check plug". Look at it carefully to see how much it doesn't fit. Next, try a different standard (ie. metric versus standard). Again, check against the "check plug". What are you looking for???? You are looking for a socket that is "just barely smaller" than the plug. Finally when you are "good and ready". Take a torch and heat up the "small socket" (what ever you have selected).... get it hot... almost "red hot". As you know the socket will expand with the heating. Now grab the thing.... "not with your hands" ... but with pliers or something. Check the "heat socket" on your "check plug" to see if it now "fits"... or how close you are to making it fit... hopefully it will be "snug fit".... don't leave it on there too long as it cools and you will have to re-heat. Again, once you are "happy" with your "test", take the heated socket and place it on the "stripped / stubborn" plug... take a hammer/or such and tap it in place to make sure of a good fit. Leave it there til it cools. You get the benefit that the heat will help break the rust of the existing plug plus now the socket shrinks to tightly grab the plug nut. Once everything is "set", try unwrenching the plug. IF you are lucky, it will likely come out/off. Good luck.

how about seeing as the ceramic has gone, why not use a wheel nut remover the type they use with the left handed head inside, it will tighten onto the plug and should wind it out. I have never tried this but have thought about doing it before.

Even bigger problem now

OK. The saga continues for the Exploder and the siezed/stuck spark plug.
Thank you guys for your help and advice, especially Joe Dirt for the link to the helpful thread.

Here's what I did:

First of all I sprayed the stubborn spark plug generously and often with PB Blaster.
Second, I pulled out the metal electrode thing that goes down the center of the plug and chipped down the ceramic so that I could fit a slightly smaller and not-so-deep socket over the rounded plug.
IT WORKED! The smaller socket grabbed hold and with a long breaker bar I turned slowly until it broke.
IT BROKE! Yes, the nut part of the spark plug broke right off and into the socket. the threads of the spark plug remain stuck in the head. AArgh! Thankfully no bits fell inside.
Next I found my appropriate sized EZ Out to pull out the stuck threads. (Thanks to JoeDirt for the link to a thread about doing just this.)
As advised I warmed up the plug part in the head and twisted in the EZ Out.
I got a good-fitting socket over the EZ Out an extension and my breaker-bar.
Sadly it was not a straight shot. The top of the shock absorber bolt was just in the way and my breaker was at just enough of an angle to...
SNAP the EZ Out! Leaving part of it stuck inside the plug in the head. AArgh!

So, now I ask you good people... How do I get the stupid broken EZ Out out of the plug? How about using some JB Weld to get the EZ Out back together and remove it? I've not used JB Weld in decades and don't have any right now, but does it sound reasonable?

Thanks again for your advice.

Yea, with those EZ Outs, you have to be STRAIGHT ON, if not then use an angled socket/extension..
Im sure someone will have an idea....I cant really think of much right now, I doubt JB weld would work, it would probably just break off wherever you put it.

I would probably cry, then seriously consider removing the head, then cry some more as thats a lot of work.

As for the JB Weld, I don't expect it to hold well enough to get the stubborn spark part out, but perhaps it would hold enough to the the EZ-Out out.

Then I would get another, better EZ Out and try again. My thought is to use a cutoff disk on my drill to take off the top of the strut bolt to get it out of the way. Should be easier to get at.

Whaddaya think?

Just take the shock off- the truck won't drop at all.

PS. I seriously considered removing the exhaust manifold to get at the plugs better. Of course I would then want to replace the nasty old manifold with something better than that bent up and squeezed up OEM junk. Then I discovered the cost of those pretty chrome ones from the dude in Michigan. NICE, but...must...focus... one problem at a time. Once I get that plug replaced I have to track down a failure-to-start issue.


1. Remove the head
2. Use a punch to push the ez-out out.
3. Use a tap or thread chaser to remove the remaining spark plug material.

An ez-out is made from hardend tool steel. In a sophisticated and well equiped shop, ez-outs (&drills and taps) can be burned out with an EDM (electronic discharge machine) but it would still require removing the head as well.

I would probably cry, then seriously consider removing the head, then cry some more as thats a lot of work.

This or consider this job "an adventure".......Down the road, you'll have stories to share

I'm open to all suggestions. Especially those that don't involve removing the head. It looks like a major pain and time that my wife doesn't want me to take. But, it is what it is. Forum thread links and video tutorials welcome.


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I broke a tap in a flywheel once. I used a dozen dremel bits . . . . the stone type, to reduce the tap to dust. It took a while.

Then I re-drilled and tapped the hole. It worked.

Spend the $10 or so on the carbide cutter dremel bit. It works fawesome. I bought one to do some porting on my nitro r/c engine and it's come in very handy for other stuff.