Stripped Spark Plug ?

We went to change the spark plugs on my son's 1996 Sentra 1.6L (116k miles) and ran into a problem. Three of the plugs came out fine and we replaced them with NGK platinum plugs. The first plug (drivers side) seems to turn but not break loose. Suspecting that maybe when it was last changed by previous owner that it may have stripped going in we decided to leave well enough alone and not mess with it. We don't know when the plugs were changed last. The ones coming out were the NGK copper V's. They actually didn't look too bad.

If the plug is indeed stripped will turning it eventually get it out? How are the threads repaired to put in a new plug? For now we are just leaving it and it may never pose a problem. I'm curious now though if it ever does need to be pulled, what that's going to mean. Nothing is ever easy.

hmmm, if its stripped you may be losing compression in that cylinder which will eventually, and i use that word very generously, cause some problems, no real method for repairing spark plug holes on an aluminum head that im aware of

They sell inserts for repairing stripped heads at the parts store, but I'm not sure they work with AL heads.

I'm not thinking there's a compression problem. The car runs well and the plug is torqued to at least 18 ft lbs. Spec is 14 - 22 ft-lbs I think. The previous owners always had Nissan do the maintenance. Looking at the 3 plugs we got out, the gap was almost to spec (maybe a mil) and v groove still evident so I'm guessing plugs maybe have 1/2 their useful life and have been in the car for at least 2-3 years. They certainly are not the originals. I really don't know what the situation is with the first plug. I'm guessing it was over torqued, but find it hard to believe Nissan would do that. We decided not to mess with the plug since the car is running fine. My son just noticed that it was torqued pretty good and he gave it 1/4 to 1/2 turn and torque stayed the same. The plug didn't break like the other 3. At that point since plugs we took out didn't look too bad we left it for fear of stripping it.
My son puts maybe 5-6k miles per year so it's possible that the remaining plug may last the life of the car that he will have it. If some time in the future it does start being a problem, he'll have to deal with it at that time.

I have read tons of info on using helio coils to fix 14 mm plugs in aluminum block.

Hi.I agree with you.If the engine is running good,don't mess with the possible stripped spark plug.If in the future you(or your Son) have to remove the plug,I would spray some P.B Blaster around the spark plug and try to carefully remove it.It may have been cross theraded when the plug was installed. Have a Happy New Year!! Diesel 1962....

a machine shop may be able to rethread it if your worried about doing it yourself. call and ask