[Vwdiesel] more TDI head questions

[LBaird119 at aol.com]

In a message dated 6/24/2004 9:31:07 PM Pacific Standard Time, 
sshourds at flash.net writes:

> A couple of 
> questions, the "service consultant" indicated that they just sort of 
> smooth out the top of mildly damaged pistions.  Is that kosher?


  Doesn't seem unreasonable.  Most of us have done it.  The damage is 
usually minimal, which is when they said they'd do it.  :)

> 
> Second question:  he also began talking about the damage that bent 
> valves can cause.  Said essentially that due to the silicon ( he wasn't 
> exactly sure) alloy the guides are made of, if a valve bends, the head 
> is destroyed and essentially unrebuildable.  Said you can try, but the 
> head will leak at the guides forever more.  Anyone know anything about 
> that?  He was a little light on specifics and then disappeared to answer 
> a phone. 


  Silicon Bronze valve guides.  The only other types I know of are cast iron 
and Phosphorous Bronze.  Automotion really brags about the latter for 
the Porsches but a regional rebuilder ended up redoing a bunch of V-8 
heads back to cast, after using the phosphorous alloy guides.
  If I'm not mistaken, we're all running silicon bronze valves in our 
1.6 and 1.5 engines.  You'd really have to bend a valve badly to deform 
through the guide and deform the bore in the head badly enough to 
make a leak.  I've seen some pretty bent valves and they didn't deform 
the head.  If they were to, it'd be the bottom little bit since it couldn't 
go 
up any further.
  Of course lifter buckets and cam lobes are at risk from heavy, valve 
bending collisions.

> 
> I appreciate all the support.  Sort of a bleak time when all you really 
> want is an Andy Griffith world....
> 

  I can sympathize.  I grew up when/where it really wasn't too far off 
from the community that show had.  Not sure I'd really want Goober 
doing a valve job on a TDI though.  ;-)
     Loren