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Old 03-27-2011, 10:17 AM   #1
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Default stripped 3rd spark plug

yeah so the title explains it, the third spark plug is stripped in the head, i was replacing my plugs and came to the third one and it was tight backing it off and when i did about 2 turns i knew that it couldn't be right so i stopped loosening it and sorta snugged it up, enough that i dont think ill lose pressure threw it but i am just a little frazzled on what to do now i dont want to touch it and **** the threads more so i cant even replace my plug, i mean the car is running on all 4 but with 3 Bosh Platinum plugs and 1 NGK BKR6E, i didnt even consider if that would be bad or not??? so my car as 148x on it should i just say eff it and find a 1.8 long block to replace my 1.6? oh and my valve cover is leaking again, on top of the 4th plug, i should probably replace it with OEM seal right? or its there another seal company you'd recommend, sorry about the 6 questions on 1 thread
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Old 03-27-2011, 10:23 AM   #2
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For the repair, you can helicoil it. Sucks but it's a solution. http://www.popularmechanics.com/cars...repair/4212608

For the oil leak, get a new VC gasket set and make sure everything's in place when you lower the VC onto the head. That should take care of it.

If you're planning on a 1.8 swap, at least still do the repairs so you can sell your 1.6 as a running engine, but disclose that the repairs happened of course.

Good luck.
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Old 03-27-2011, 11:35 AM   #3
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FYI, I know some VC seals have separate rings for the spark plug holes. Miata gaskets have them built in. I've had great luck with any of the NAPA/O'rilley's/Auto Zone gaskets I've bought. Don't forget a tube of gasket sealer on both sides.

Koto's right, heli-coil is your only option I know of before you replace the head.

Solutions, from cheapest to most expensive:
1. Do nothing
2. With good luck, take it out and it's fine.
3. With bad luck, take it out and heli-coil.
4. Replace head with used 1.6 unit.
5. Rebuild block with minimal machining and gasket/ring kit.
6. Used 1.6 engine.
7. Used 1.8 engine and swap kit

The built 1.6 or 1.8 option is in there somewhere. Personally, I'd back it out and see if I can fix the threads, you could possibly be okay with just chasing the threads, but I'm not sure how you'll clean out any chips. You'll have to figure that out anyways if you heli coil.

Then again my Miata isn't a DD, so if it's down a bit while I figure out my options, it doesn't matter.
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Old 03-27-2011, 02:42 PM   #4
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hey curly....cant he just pull the head...tap the threads for the spark plug, get a new head gasket and put it back together? well thats what i would do
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Old 03-27-2011, 02:57 PM   #5
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Quote:
Originally Posted by Rusty323 View Post
hey curly....cant he just pull the head...tap the threads for the spark plug,
If the existing threads are mangled, then it's quite likely he won't be able to simply run a tap through them and be good as new.

He needs to take the head off and bring it to a machine shop. They will be able to re-drill the hole slightly oversize, re-thread it, and install a heli-coil, which is a sort of wire-spring device which is intended for repairing this sort of problem.

Info on heli-coils, for those not familiar with them: http://www.emhart.com/brands/heli-coil

They actually sell DIY kits for these as well at auto-parts store. Honestly, this is one job I'd be slightly nervous about doing in the garage with a hand-held drill, though. It's not that expensive to have a shop do it, and if you screw it up the first time, you need a new head. I've only ever done one (on the head from a VW Beetle) and while it worked, I didn't get it just perfect and the plug was always angled a bit oddly after that.
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Old 03-27-2011, 03:06 PM   #6
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ok got ya
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Old 03-27-2011, 03:21 PM   #7
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Joe is right, but I would defiantly try to heli-coil it myself before taking it to a machine shop. It will save you a bunch of money. But I would only go that route if you are comfortable with the task, familiar with the tools, or even have the tools. And you can get the heli-coil in just the thread you need. I have two of their "Master Kits" but you would only need the one for what your looking for. The Master Kits get pricey.
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Old 03-27-2011, 03:45 PM   #8
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I did this (helicoil) on an old Pinto Iron Duke 4 banger. Used a drill press to get it straight. You HAVE to remove the head to keep the chips out of the cylinder, but that's the worst part of the job. Since you need to replace the VC gasket anyway, might as well do it right. Semi stripped threads may blow out.

EDIT: Check out McMaster-Carr for Helicoil kits. Hell, they probably have them at your local auto parts store. Don't bother buying the insertion tool, you can do it with needle nose pliers.
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Old 03-27-2011, 04:18 PM   #9
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Are you certain it is stripped? It sounds to me more like it's just galded a little in the head. Be ready for it to be stripped, but you may find that once you remove the plug it was just a little stuck in there.
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Old 03-27-2011, 07:12 PM   #10
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You can totally tap it as it sits. Just vacuum out as much as you can and the rest will simply burn up or get shot out the exhaust on restart. Hardest part would be getting it straight and not going too deep with the heli.
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Old 03-27-2011, 08:20 PM   #11
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ironically i ran into a buddy who works in a machine shop a 1/4 mile from my place, and he blew a loose plug straight out of the head off his mini cooper, and he didnt even take his head off he drilled it out and used a high powered vacum and greese on a stick to pick up the extra heavy shavings off the top of the piston and he heli coiled it he said he'd be comfortable doing mine, but it just makes me alittle nervous because if he F's up then i am F'ed worse, what do you guys think i'd rather not take the head off because i am soo impulsive ill have to do all new high compression pistons and what not
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Old 03-27-2011, 09:12 PM   #12
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You can't replace pistons by simply removing the head. All you do is replace the timing belt if it hasn't been done recently, the valve cover gasket which you said it needs, and the head gasket.
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Old 03-28-2011, 09:31 AM   #13
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I don't know why you guys are messing around with heli coils. Napa sells a thread repair kit with sleeves that have a flange at the top. Essentially you tap the head, and then tighten the sleeve until the top bottoms against the head. The sleeve flange acts as a new seating surface for the spark plug and sets the depth of the sleeve. Then red loc-tite holds it in place. They give you a drill/reamer to open up the head but it dosent work worth a crap. I did this on a 97 v6 Tacoma and needed an adjustable reamer to open up the hole. A ton of grease kept most of the shavings from going in the cylinder.

The biggest problem you are going to run into is finding a long enough drill bit or reamer to reach down in the spark plug hole and still be able to turn it with a drill. The reamer I got had a hex head on the end of it to drive with a ratchet.

If it was my car I would yank the head, drill it from the back side, tap it, sleeve it, and then reinstall. If you are going this far you might as well put it on a mill or take it to a machine shop.
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Old 03-28-2011, 09:54 AM   #14
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Umm maybe because Timeserts are like $80 for the cheaper kit, and self locking heli coils work just fine and are way cheaper.
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Old 03-28-2011, 09:58 AM   #15
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On second thought you might have some carbon gunk on the end of the plug. Try to get some wd40 or pb blaster in there to lube the threads and break down the gunk. Take small 1/4 turns loosening and tightening to get the plug out. Don't he man it all out in one shot - work it back and forth.

I would be prepared though to yank the head. Not having the plug seated will likely result in the plug rattling loose popping the plug out after a couple 10k miles.
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Old 03-28-2011, 10:08 AM   #16
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I would helicoil it and just start shopping for a 1.8.
This way you have a good excuse for the upgrade

I've used different gaskets, both oem and aftermarket (kragen/o'reillys) and like curly, had good luck with both. I think its all a matter of putting it on correctly, putting the silicone beads in the right spots and right amounts, making sure the area is dry/clean and tightening the vc correctly. Doing either one of those wrong will result in a leak whether its oem or aftermarket.

good luck
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Old 03-28-2011, 05:20 PM   #17
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Quote:
Originally Posted by kidrabbit84 View Post
I would be prepared though to yank the head. Not having the plug seated will likely result in the plug rattling loose popping the plug out after a couple 10k miles.
well hell, according to your guess if he has a couple 10k miles, which I'm guessing is 20,000 miles, why even **** with it? I would never drill or tap a spark plug hole with the head still on the engine. Its stupid, why not do it right once and never have to mess with it or worry about shaving that did or didn't get stuck to the grease or sucked out with a vacuum cleaner.

Just like I didn't drill the oil pan in my car. Sure there are plenty of people that do it, and I'm sure some don't have the resources to pull the motor to do that. But if you have the resources and capabilities to pull the cylinder head off, then do it.

And like Curly said, while your in there, change the timing belt. You could also go a step further by putting in a new water pump, since you probably don't know if its ever been changed. Then you buy a new head gasket and you're all set.
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Old 03-28-2011, 08:13 PM   #18
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Umm maybe because Timeserts are like $80 for the cheaper kit, and self locking heli coils work just fine and are way cheaper.
more like $47.89 for the kit. I have had helicoils come out with the plug the next time you are in there. These seem to stay better.

Last edited by kidrabbit84; 03-28-2011 at 08:29 PM.
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