[s-cars] Loose spark plug disaster

[Trevor Frank]

I dislike Helicoils in general and really hate them for a spark plug
hole.  They have a tendency to eat away at the cylinder head after a
while and they also tend to back out.  They also do a poor job of
conducting the heat away from the plug and tend to run the plug hotter.
My general rule is only use them if you have to. The one thing they do
have is they are cheap and easy to install.  If you have to do lots and
it is labor and cost sensitive then you might be forced to.  But why
install a 10 cent part when your cost of labor is 10 fold and you only
have one to do.  Stepping down off of the horse now.

Keenserts and Timeserts are what I like to use.  For a cylinder head
spark plug hole I would use a timesert.  I have on other cars in the
past done this job at the track in under 30min.  The best way is to pull
the head.  You can however very carefully do this with ought.  You will
want to try to vacuum the cylinder out after and or very carefully use
some chewing gum or silicone on the end of a piece of wire, that is
after you drill, counter bore and tap.  Also make sure you are at TDC.
You don't want to put any more partials on the cylinder then you have
to.  This also ensures the you will not get anything in the intake and
exhaust tracks.  If you have a boroscope or you can borrow one, you can
use it to ensure everything is clean when you are done.  Also make sure
that the insert doesn't extend past the cylinder walls.  If you do this
it will not have enough contact with the cylinder, it will not be able
to cool itself and will end up heating up and melting it's self away and
possibly take the cylinder head with it.

http://www.timesert.com/sprksert.html

Good luck,
Trevor.

-----Original Message-----
From: colin gans [mailto:cgans at shaw.ca]
Sent: Saturday, March 29, 2003 10:35 AM
To: s-car-list at audifans.com
Subject: [s-cars] Loose spark plug disaster


Yes, it happened.

Last week while my wife was driving our 93 S4 the plug from #5 cylinder
completely unthreaded destroying the spark plug boot and damaging the
threads in the cylinder head to the point where a new plug can find no
purchase.

Any BTDT? Can the cylinder head be tapped (?) so that a new plug will be
secure?

Thanks,

Colin Gans



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