number six cylinder launched spark plug


New Member
May 26, 2008
Greensboro NC
i am wondering if anyone has had the same problem that just recently happened to me, if so what was the outcome. i drive a 2003 mustang GT and the other day i was riding along and i heard a noise. a small bang under the hood so i pull over to check it out. upon investagation i discovered that the number six cylinder spark plug had launched out of the head and got stuck in the corresponding coil pack. i thought i might have droped and valve but i pulled the valve cover to check and the valves where fine. i was wondering if anyone has any answers for me before i put my mind to ripping the head off and checking it out. thanks for any information you can give me.
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Feb 19, 2007
Sacramento CA
this is a pretty common thing on our engines. it usually happens after people change there plugs and dont properly torque them down (13ftlbs). i have also been told that it happens when people dont put anti seeze on the threads. if you do a search you will find a butt load of threads on this subject. but from what i gather the best thing for you is to take it to a shop and have them install a timesert (do a google search to see what iam talking about) its the easiest way to fix the problem and its pretty quick. if your really worried about it have them bore scope that cylinder.


New Member
Apr 25, 2008
Okay i just had this problem a week ago after buying my GT and i just got it back. Same thing happened so i took it to this guy who put a timesert in cost me about 250.00 for him to do it and it worked pretty good not to mention the spark plug hole had already been cut once. Towed it home and heard a loud knock me pissed off!!! Got it towed to the nearest dealer say i had some bottem end problems and i prob spun a bearing. Harassed the Ford dealer that sold it to me for like two weeks and the finally decided to take a look at it. Sure enough the piston had something hitting the top for awhile and the bore was all f**ed up. So good news is that i had 84,000 on motor and now i got a motor with 55,000 miles. In ur case dont drive that bitch till its fixed. It sucks bad man!!


May 29, 2007
Stanford University
As stated above, its common in our engines, we were discussing this in another thread, and someone pointed out that our heads only have a little over 4 threads, while a park plug has at least 3 times as many threads lol :nonono:

so yeah options:
1. do a timesert kit, or a heli coil kit (google :p, but not as successful as the timesert)

2. get some used PI heads (be very wary, you get what you pay for)

3. Look into some Patriot heads or Fox Lake now that you might be in the market for new heads :D

Hopefully, you didn't get any more damage to the engine besides the blow out, but i'm sure you'll find out when you pull the heads.


Apr 30, 2006
Clarksville, TN
Common yes. Common in an 03 no. Ford had fixed the problem in 03 and added threads to the spark plug holes. You or who ever was last to change the plugs did not do it right and didn't torque them down.


10 Year Member
Aug 23, 2003
Rhode Island
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Not all 03's are "fixed". My '03 ejected its first plug at 4900 miles. The plugs had never been touched (8 miles on the odometer when I bought it). Timesert repair has held for 4+ years, though only 16K miles on it now.