912S low compression 1 cylinder

We pulled the cylinder this morning and found a cracked exhaust valve.  (pic attached).   I would advise anyone with compressions below the recommended specs to fully investigate the cause prior to further flight.  

With an occasional borescope inspection it is possible to see valve damages coming up and act before a valve fails (completely). Did you find any damage on the cylinder wall or is it on the head and valve “only”? You have done the right thing for sure, Jim!

Now that you come so far, are you not tempted to replace the valve yourself?

interesting that it’s the intake valve that failed…

Folks, I am not suggesting that everyone must own his own borescope but sharing one in a group of 4 or 5 seems to make some sense to me and inspection a lot easier and more efficient.

Peter Kl. wrote:

With an occasional borescope inspection it is possible to see valve damages coming up and act before a valve fails (completely). Did you find any damage on the cylinder wall or is it on the head and valve “only”? You have done the right thing for sure, Jim!

Now that you come so far, are you not tempted to replace the valve yourself?

interesting that it’s the intake valve that failed…

Folks, I am not suggesting that everyone must own his own borescope but sharing one in a group of 4 or 5 seems to make some sense to me and inspection a lot easier and more efficient.

To clarify, it was the exhaust valve.  Cracking it open and replacing the valve is above my pay grade.  The entire cylinder head was sent to Lockwood today.  We'll see what they recommend in a day or two.  I'll keep the group posted.  

As it turns out, the valve seats were damaged.  Lockwood recommended a new head.  It was in stock and will be sent out today.

Hi Jim,

I'd want to know how the valve seats got damaged. This isn't normal.