[s-cars] The "myth" of plugs blowing out of 20vt heads.

[Wayne Dohnal]

When I bought the S4 many years ago a few of the plugs were worse than 
finger tight.  They were backed out of the holes a couple of turns.  I've 
replaced them once and check the torque occasionally.  My experience is that 
the first time I checked they took about a quarter turn to retorque.  The 
2nd time they took less turning.  The 3rd time, just a little bit.  Ever 
since then they've stayed tight.

I'm skeptical of the dissimilar metals explanation because I also had a 
Plymouth Voyager with a Mitsubishi aluminum head engine.  On that one, if 
you didn't use anti-sieze when the plugs went in, you were in big trouble 
trying to get them out, expecially the difficult to reach ones.  It took so 
much to break them loose that I was honestly afraid of snapping them off in 
the head.  And they had a pretty light torque value, too.  I've stripped too 
many aluminum threads to do it by feel.

It was ironic that I had 2 aluminum-headed engines where one you couldn't 
get the plugs out, and the other you couldn't keep the plugs in.

Wayne Dohnal
1994 S4