sl6 sages in the forum may excommunicate me for working on a 99 kia sephia 4cyl. engine but here is my peculiar question. a scope plugged into this badly misfiring engine indicated bad sparkplugs. 3 of the plugs came out easily. #2 plug is very hard to unscrew. i did get it about 2 turns, but am concerned the excessive torque required tomove it will damage the head. will have to use a breaker bar or a larger ratchet. the plugs are bosch and the head is an aluminum dohc. are you aware of any strange condition with this engine concerning plug removal and does anyone know of a technique tosafely remove this apparently(at least partly) seized plug.never saw this condition before . what could cause a plug to seize? over heating? uncle moe says prior replacement may have stripped the plug hole thread necessitating a helicoil installation and these are verytight. never did that repair, but the excessive tightness doesnt seem right to me. if any have insight or experience with this problem will certainly appreciate it. bob fisher

Somebody did not put any lubricant on the plug threads when installing them in this aluminum head, and/or spark plugs with cut rather than rolled threads (such as Champions) were installed. If it's tight to come out, the head threads are almost certainly already damaged and you should plan on installing a spark plug thread insert. You may want to warm up the engine and then try turning-out the plug again; aluminum expands at a greater rate than steel and this might cause it to let go of the tight plug.

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Too many people who were born on third base actually believe they've hit a triple.

Having the engine hot as Dan suggested is about the best thing to try. Ofcourse soaking the threads with PB Blaster or WD40 will help. Also after reaching the piont the plug locks up, reverse and retighten the plug before trying to back it out farther. Everytime it tightens up when trying to remove, turn it back in then back try to gain a few more turns out.


Take it easy and slow, work the plug in & out and let it come out at its own pace. Force it very little, but some. Engine hot, and respray the lube after every few try's. It should come out a little more each time you try.

Dont worry, the worste thing that can happen is you have to remove the head



Jess