[T3] Spark plug blown out of #4 cylinder

[Jim Adney]

On 18 Jul 2011 at 21:16, crash 69 wrote:

> In talking with experienced folks, I've been told TimeSerts are better than
> Helicoil.  I've never used them myself.  Any opinions out there?

The one thing that I don't like about the solid inserts is that they 
tend to come out again each time you remove the spark plugs. The 
TimeSerts are better, because the nose gets swaged into the head, 
making backout much less likely. OTOH, this swaging operation puts 
the alum around the chamber side of the head under tension, in a 
place where the heads tend to crack anyway. 

HeliCoils have a couple advantages. One is that they spring outward 
and tend to lock themselves in position, but over their full length 
and not with excessive force. The other is that they leave the 
seating face where the plug comes to rest untouched. Both of these 
minimize changes in the thermal path from the plug to the head.  

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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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