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Discussion Starter #1
So recently i had a plug come completely out of the head. the threads didn't appear to be damaged at the time but upon further inspection it wasn't fully threaded into the hole. when i tried to tighten it back down it wouldn't go all the way with out a lot of force. i did this slowly in several attempts, in and out, and think it's seated back right. Is there any cause for this other than being cross threaded to begin with and is there a fix that doesn't require removing the head to re-tap the hole again?
 

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Doesn't sound good. The best bet is pulling the head (to prevent shavings getting in) and tapping the hole. If it's smurfed you can Heli-coil it.
 

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More than likely if it wasn't tightened all the way and backed out then carbon has gotten into the threads. Hopefully you haven't galled them up by running the plug back in.

I would say to fix without pulling the head to bring that piston up to TDC, coat your tap liberally with grease to hold any shavings, run the tap into the hole, then use a shop vac with a piece of vacuum hose small enough to get into the hole in case any shavings did get in the bore. Then I would blow the hole out with compressed air. Reinstall your plug, hopefully it is not loose going in or you may have to go to the helicoil. Good luck.
 

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Discussion Starter #4
alky would you happen to know what size tap they use. Still don't know if i'm comfortable tapping with the head on but i'll check the plug again this weekend. I'm thinking it was just carbon build up too.

thanks for the insights.
 

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14 mm thread but not sure of the pitch. And you are not really taking any material out (hopefully) and like I said be sure to pack the open flutes of the tap with axle grease to hold any material you do take out.

Take a plug to the hardware store or more likely a NAPA or O'riely's and match it up with the tap. Good luck!
 
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