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Blown Spark Plug

1953 Views 3 Replies 3 Participants Last post by  jimskater
Earl K (10851CS over on North American Motoring) was on his way to Vegas for AMVIV this morning and had a problem. He blew a spark plug out of the head, frying the wire & possibly damaging the head. The sparkplug itself seems fine.

Earl's asking me to pose the following questions:

Anyone else had this problem?

Any ideas of the cause?

What's the fix & how much will it cost?
1 - 4 of 4 Posts
There have been previous reports, including these on Webb Motorsports' forum (in the US):
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.
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