RE: sparkplugs coming loose

["Smeins, Larry" <lsmeins@ball.com>]

This reminds me of an experience I had with my 87 5kcst before discovering
this group.  I had replaced the plugs with a set of NGK tri-electrodes and
couldn't find a torque spec so I used my calibrated hand that had put many
plugs in aluminum heads on Porsches and VWs. A couple months later I noted
an ignition miss on acceleration while driving to work one morning.  The
farther I drove the worse it got and by the time I got to work I was running
on 4.  I had a friend take me in to buy cap, rotor, and wires at lunch time
and proceeded to attempt to fix the problem.  I noticed one plug was loose
so I tightened it and replaced the parts I had purchased.  It wasn't fixed
so I drove home slowly on 4.  At home I pulled the plug that had been loose
and to my astonishment and dismay I found the center electrode was missing.
I had visions of plug electrode embedded in the piston or head.  I sent off
a nasty letter to the US VP of NGK and borrowed a bore scope to inspect for
damage.  I found nothing with the bore scope and NGK promptly replied asking
for more detail.  A new plug brought the engine back to its normal self.  A
few days of thinking and I realized the loose plug had lost its heat sinking
and probably got very hot.  I must have melted the electrode out of it.  I
still haven't found a torque spec for the plugs in my engine but I have been
much more careful to keep the plugs snugly tightened.  Is that spec in
Bentley someplace?  I sent another letter to NGK explaining that the problem
was my fault and thanked them for their prompt reply.

Larry  

Date: Thu, 20 May 1999 01:18:23 -0400
From: Phil Rose <pjrose@servtech.com>
Subject: sparkplugs coming loose


>Speaking of the need to _retorque_ brings to mind my experience with
>sparkplugs a couple of weeks ago. When I bought my '91 200q a year ago, I
>soon got to checking the condition of the sparkplugs. I posted about the
>fact that some *^!#$^% so-and-so had installed several of the plugs so
>loosely that they were removed with little or no effort. So when I
>reinstalled the old plugs I made certain they were done to the factory
>spec.

>Fast-forward about a year, and I've decided it's time to treat my car to a
>new set of F5DPOR plugs, thanks to a nice sale price at TPC. So, off come
>the wires and...damned if nearly every plug didn't come out every _bit_ as
>easily as I had complained of last time. Probably didn't even really need
>to use a ratchet handle! Although the insulators looked great, a lot of
>gummy gunk was covering the plug threads and gaskets, although these had
>been well cleaned up at the last installation (10k miles).

>So, what gives? Something special about the aluminum head and narrow dia.
>plugs? BTW, the old plugs had been installed on a cold engine and were
>removed when cold.


Phil Rose				Rochester, NY
'91 200q				mailto:pjrose@servtech.com
'89 100