Spark plug threaded section sheared, left in head

Buick Lacrosse 2006 with the GM 3800 engine. Told my dad I’d do some work on his hunk-o-junk and the #1 spark plug sheared where the hex flats are connected to the threaded section. Is there any hope of getting the threaded section out of the head without removing the head? Trying to review some YouTube videos now.

Bad start to the Saturday. I got the #5 and #3 plugs out okay before this one and was not using excessive torque on a standard 3/8" ratchet, not even using the full leverage offered by the handle length. I suppose I could have sprayed some P’Blaster in there first but really don’t think I did anything wrong besides mess with an old rusty car that was running before I got my hands on it :-/ I’m pretty sure these are the original plugs and wires from a Michigan car with 185,000 miles.

You might try a large easy-out. Google that if you don’t know what it is.

Pb Blaster the remnent several times over a few days. You might get lucky.


Thank you, I am familiar with it. I just saw a guy use a square shaped one that looked pretty realistic. Hopefully I am overreacting. Thankful I took a minute to stop and not make things worse yet!

Success! I forgot that I had this set of extractors until I started a web search for one specifically for spark plugs. D’oh!
I first cut apart one of the other plugs to see what I was dealing with and to choose the best size.


Go buy a lottery ticket before the luck fades! :money_mouth_face:


Yeah I am gonna think hard before I decide if I am gonna try the rear trio of plugs LoL

Smart guy. Edit

This is the warning Motorcraft states on their spark plugs.

Caution: Do not remove plugs when the engine is warm or hot. The engine must be at room temperature when performing spark plug service. Removing the spark plugs from a warm/hot engine increases the chance the threads could be damaged.


I don’t don’t think this problem is b/c of an error on your part. Parts that refuse to budge is pretty common occurrence in auto repair, diy’er or pro. Me, I’ve never had a spark plug stick like that. To prevent it from happening what I do is coat the spark plug threads with a very thin layer of moly-grease before installing them. I don’t use thread penetrant before removing them, but I do vacuum out the bottom of the plug area to prevent any debris there from falling into cylinder during removal process.

Just listening to recent Car Talk podcast this AM. Caller said wheels on his Euro-car stuck on, couldn’t get lug bolts out. Shop got them off using torch. Reinstalled wheels. Then caller later had flat, found he couldn’t remove the wheels again … lol … Ray suggested to prevent wheels from continuing to have this problem, lube the bolt threads before putting the wheels back on. More common w/ lug-bolts than lug-nuts apparently. I should point out that some say lug nuts/bolts should never be lubed, as it can make them come loose. Never had that happen myself.

That photo looks like there’s head metal in the threads, which will require a helicoil type repair. Is that the case?

I expanded the image, and I don’t see any head material on the threads.

You’re good to go.


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Do not follow George’s advice.

All spark plugs manufacturers warn not to do this.


But when is the last time you’ve changed plugs on an engine with aluminum heads that can go 100,000+ miles between changes ?

Plugs now I’m told have anti seize on them already. A car that old though with close to 200k with the original plugs, likely had none.

To quote my late Uncle Ben, who taught me how to fix cars amongst lots of other things “don’t fix what isn’t broken”.

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When I bought my '99 Monte Carlo brand new (3.8 V6) it came with “100,000 mile” plugs. Working on my own stuff since the early 70’s, I knew the pain of trying to remove rusted bolts/nuts that had been in place for years.

At around 70,000 miles I thought I’d remove the front plugs to check them. One of the plugs really gave me a fight, I thought it might break. In went 6 new plugs (The rear cylinders are a pain to access!). Sometimes “don’t fix what isn’t broken” will lead to worse trouble down the road.

NGK and Denso have been used coated plugs for over 20 years.

This was a Buick though likely using ac plugs not ngk. It’s not clear whether the failure of the plug was due to not using anti seize or just a failed plug coming apart.

Haven’t done that experiment. Seems problematic. Don’t think I ever will … lol …

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There seems to be some difference of opinion out there especially among folks that have to remove them. Might be different for iridium and platinum plugs versus the standard. For ac anyway the engineers seem to say it reduces the ground of the plug. Installers seem to say big deal, it prevents seizing in the head. Takes your pick.

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