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Repairing a stripped Spark Plug hole


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16 replies to this topic

#1 syphon

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Posted 12 November 2003 - 02:34 AM

I was driving home tonight when suddenly my car made a loud popping noise, a small puff of smoke came out, and suddenly ran with a LOUD clacking noise.

A bit of investigation under the hood shows that for some reason, my front drivers side spark plug shot out of the hole.

We tried putting the spark plug back in, but it became apparent that the threads were stripped out.

Has anyone ever repaired these threads? (helicoil?). Is this possible? Who's done it?

#2 Scrub2k

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Posted 12 November 2003 - 02:38 AM

I Have Heard of it being done with a HeliCoil, but fortunatly ive never had to do it, i cant think of any reason that it wouldent work, im sure someone around here has done something to this nature.

#3 Caboobaroo

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Posted 12 November 2003 - 06:34 AM

I had to heli coil my sparkplug hole before. It wasn't that bad. I went to Car Quest and got the right kit for it and in like 30 minutes if that, it was done. Just make sure not to get any metal shavings down the hole or you might be sorry:banghead:

#4 Dr. RX

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Posted 12 November 2003 - 09:07 AM

I think if you bring that piston up to top dead center before you start, you might be able to pull all the metal shavings with a shop vac.

#5 Guest_subu luvr_*

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Posted 12 November 2003 - 10:14 AM

try a "thread chaser" first.

they are made just for spark plug holes, cost about seven bux, and it cleans up the threads.


you probably had that plug working loose for months, and i would
expect that 97% of the threads are fine, except for the top few turns.

#6 syphon

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Posted 12 November 2003 - 01:04 PM

I dont know on the threads.

When we tried putting the spark plug back in... it would get tight for a little bit and then eventually get lose again. It felt like some threads were grabbing but then it slipped loose again.

Is there anyone in the Seattle area who's done this before? Anyone who would be willing to do it for me? (I could pay you of course).

I have bad experiences drilling out bolt-holes. Just ask my thunderbird and its new harmonic balancer :-)

#7 torxxx

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Posted 12 November 2003 - 01:58 PM

sounds like its stripped.. I know people have done it with a helicoil... thats my best advice...
heh or wrap some tinfoil around the threads before you put the plug back in. lol <---- Dont do that one..

#8 Nug

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Posted 12 November 2003 - 07:50 PM

There's a kit called SAV-A-THREAD or something, made by helicoil, That puts a steel sleeve in the s/p hole. Comes with a tap, expander, and three sizes of inserts. Grease the tap up, run it down into the hole, it will cut the hole oversize for the insert. The grease keeps the chips on the tap instead of on the engine. Put the insert on an old s/p. put high temp rtv on the threads, run it down in there, remove s/p, put the expander in the insert and whack it with a hammer. Problem solved.
The kit ain't cheap, but with the availibility of more inserts being pretty good, you can use it many, many times.

#9 syphon

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Posted 12 November 2003 - 10:22 PM

Where can I get this sav-a-thread kit? I didnt know they made them for S/P holes.

#10 Nug

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Posted 12 November 2003 - 10:28 PM

I know the Boys of Pep has it. It's in a yellow package w/red lettering.
All-Pro has it too, and I can't imagine Napa NOT having it.

#11 syphon

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Posted 14 November 2003 - 12:26 AM

Ok, so I bought this kit from schucks.

It's an oversized tap, and then aluminum "sleeves" that you fit the spark plug in.

Basically I just wrench the tap in, then remove the SP washer and insert the plug into the sleeve. I put threadlock on the outside of the sleeve, and put the whole thing in the head. Then, after the threadlock dries, I pull the plug out, put the washer back, and re-insert.

Does this sound good? Anyone have any suggestions before I do this?

#12 Nug

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Posted 14 November 2003 - 07:48 AM

I prefer the steel sleeves, but anything is better than what you have now :)

Make an effort to keep the chips out of the engine. I do this by grasing the flutes of the tap. You can clean the threads with brake cleaner, I guess.

Back the piston off. You don't want the top gouged bt the tap. If you get chips in the cylinder, maybe rototate the engine until the exhaust valve is open (maybe start right here) and you can blow compressed air in there and blow the chips out.

Good luck!

#13 syphon

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Posted 14 November 2003 - 10:05 AM

If metal shavings do get in the engine, they're most likely just going to blow out the exhaust valves, right?

#14 Nug

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Posted 14 November 2003 - 10:19 AM

Theoretically, yes. But generally when something drops down in the cylinder, the piston smashes it into the head, and it becomes part of the head or piston. I have a piston out of a HMMWV with a glow plug tip bashed into it. Shavings, chips, etc. I wouldn't worry too much about, but the less you get in there, the less i'd worry. Got compressed air? i'd blast it in for a while when I was done just to make sure.

#15 desertsubaru

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Posted 16 June 2011 - 11:19 AM

I know this is an old thread but I need to know if the spark plugs are 14 mm thread?



#16 81EA81

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Posted 17 June 2011 - 01:53 PM

Idk about the thread size but when i bought my Brat of course I did a tune up which included spark plugs. when the original ones were on there way out it would get loose then tight then loose again......when i got them out the threads were pretty chewed up, thankfully I was able to get the new plugs to thread in o.k. again loose then tight then loose again then kinda barely tight enough to work. its been about 6000-7000 miles on it since then and I fear every minute my plugs will blow out:eek: Im willing to leave it alone for now but I would like to be prepared for the fix when when the time comes.
any opinions or first hand experience?

#17 kayakertom

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Posted 18 June 2011 - 11:15 AM

Yes, 14mm.


I know this is an old thread but I need to know if the spark plugs are 14 mm thread?






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