Dented pistons!

[Charlie Smith]

Earlier, David Vander Schaaf wrote:
>
> Hey all,
>
> We've been tearing into the motor on my newly acquired '93 90s V6 12v.  We
> have one cylinder head off and sure enough the exhaust valves are bent.
> Further more, the poor valves left big 'ol dents in the pistons.  Does
> anyone think the dented pistons will pose any long term problems if we don't
> replace them?

Frequently this type of damage will cause cracks in the pistons.

Pull the pistons out of the block, and I almost guarantee that you
will find the top ring is tight or stuck solid in the ring groove
right near the exhaust valve recess in the top.

Check the connecting rods for straightness.  I have seen connecting
rods bent "S" shaped after the piston has hit something in the combustion
chamber.  This may not have happened from light contact with the valves,
but if the impact was enough to leave big dents in the piston tops, I'd
sure have a good machine shop check them.



> Anyone have a pair of 12v heads laying around with good
> exhaust valves that you would like to sell?

It might be cheaper to find a low mileage engine in a junk yard.

    - Charlie


  Charlie Smith   charlie at elektro.cmhnet.org  614-471-1418
  http://www.elektro.com/~charlie      Columbus Ohio   USA
  http://www.elektro.com/~audi     photos & technical info

  95 S6 Quattro  -  24 PSI, RS2 6 speed, and other features
  96 Dodge Ram   -  30 PSI, w/Cummins turbo diesel