Blown Spark Plug

There have been previous reports, including these on Webb Motorsports' forum (in the US):
http://www.webbmotorsports.com/forums/viewtopic.php?t=305&start=0

Blown sparkplugs are of two types:

a) someone forgot to properly tighten one and it unscrewed itself (easy to tell as the thread is intact)

b) the piston blew it out, thread and all. Happens mostly on race cars or cars that have been modified by silly persons......


In the case of a) new wire, same plug (if alive), cost zero and some embarassment for SOMEONE!

In the case of b) and have an honest mechanic, they can install a thread insert in about a half an hour and get you going. That won't solve the WHY??? The why lies in either a silly mod (like shaving the head to increase compression ratio without proper measuring of clearances) or using to much boost or "funny fuel".
Hope this helps

It's been fixed, using a helicoil insert. Checked at dealer service, owner was assured sparkplugs were torqued correctly & the three other cylinders were "fine". Owner then took car on a trailer to reliable mechanic, remaining sparkplugs were way loose.

From what I've seen, 02/early 03's might have a tendency towards this sort of problem.

Thanks for your help.