[s-cars] Lets get Dave a new motor, was: S-car Head Repair

[Tom Mullane]

Serge,

According to the dealer's account of what happened, the valves were bent
when the crank bolt was being removed, with the belt off.  When the belt is
off, the cam does not turn; the cam must turn for more than two valves to
contact the pistons, regardless of how far the crank is turned.

Finally, the bolt was removed, the belt changed, and the engine started.
Assuming that the belt was put back on properly, there would have been no
further piston/valve contact except possibly some additional contact between
the two bent (and now possibly stuck part way open) valves.  But even the
valves that where bent during the crank bolt removal should not be able to
cause significant damage to the pistons at this point; with the cam back in
time, there would be nothing holding them open from the cam end.  Piston
contact would just push then shut.

My contention would be that the valves where not bent by the force of the
engine running, but by the monkey lad with the big bar.  IME, damage to the
piston *should* not be much more that a "clean spot " or small nick.  I
would not recommend rebuilding an otherwise good running engine for such
minor damage.

The truth is, without actually seeing the damage, we can only speculate.
But I have replaced valves on cars that have seen broken belts, and I have
seen few pistons that gave me any reason to do more than change a few
valves.  Think about how the damage occurred; it would have been a totally
different situation if the belt let go on the interstate.

Tom

----- Original Message -----
From: "serge" <serge411 at speakeasy.org>
To: "Tom Mullane" <tmullane at snet.net>; <s-car-list at audifans.com>
Sent: Wednesday, December 18, 2002 2:08 PM
Subject: Re: [s-cars] Re: S-CAR-List digest, Vol 1 #851 - 15 msgs


> Tom Mullane wrote:
>
> > Take the offer, fix the car, and get on with your life.  The last thing
I
> > would want, if I were you, is to have them start removing pistons.  This
is
> > not a race car; a couple of marks on the top of a piston or two should
not
> > affect the drivability or life of the car.
>
> Ok, I was gong to pass on comment, but suddenly I find myself overfunded
by
> about $.02.
>
> I think the offer to replace the two valves is a nice starting point, but
> not nearly adequate fix. If the car was started and allowed to run for ANY
> length of time, I don't see how ALL the valves did not come in some
contact
> with ALL the pistons. Pistons are designed to withstand
> compression/expansion force, not being smacked in the middle of the crown
by
> sharp metal objects (valves). ALL engine parts that were not designed to
> come into contact with one another should be replaced. Remanufactured head
> assembly seems to be a wise move, since parts, measurements, tests and
> possible machining are time consuming and expensive.
>
> WRT marks on a piston, this is really troubling to me. What force is
> required to bend the two valves? I would think it is something like the
> force of taking a big F hammer and striking a cold steel chisel to the top
> of the piston a couple times (hence the score marks). Would anyone be
> comfortable with building a 9.4:1 compression engine that regularly sees
20
> psi of boost, using that same piston?  I would not be. I have seen an EM
and
> turbo glowing cherry red (name withheld to protect....oh hell, we all know
> it was Pizzo) from a spirited drive. That's a lot of heat, imagine what
was
> going on inside the combustion chamber to cause that. Still ok with using
> that piston?
>
> On the service side, umm, not much there. Aside from a neat little dealer
> dance to try to dodge some bullets. David has not had his car for how many
> weeks? If the dealer has offered a remedy, is that not an admission of
> wrongdoing? Therefore, are they not liable for any necessary repair work
but
> also rental car, attorney fees...
>
> To the state AG: Please make Hoffman provide a new engine for David's
wife's
> car, and make it an RS2 spec, just for the grief and time spent dealing
with
> them. Please fire the technician responsible, and place the dealership on
> some kind of probation, during which they are not allowed to scrap any
good
> running engines.
> <end rant>
>
>
> Serge Filanovsky
>
> 95 S6 Avant
>
>
>
>
>