Anybody out there experienced burn-through on their exhaust valves?

Car: 2012 Justa (N16)
Owner states:
Only premium top-tier fuel
Never overheated

Leakdown test showed 95% leakdown in cylinder 4, and adding oil to the cylinder didn't reduce the reading; at first I thought it had dropped a valve seat, but the valves were not stuck open and they were moving normally when I turned the engine over manually. I used a borescope in the exhaust port to find the problem.

 

That's great that you found the culprit.

 

I had that happened on two different heads it's pretty much a known issue.

 

Known to whom? This was a first for me. Did you find out what caused it on your valves?

 

When I went to the machinist he said it's a very common issue for this to happen. When I
purchased the vehicle it wasn't running the compression was vey suspect on #3 cylinder.
After taking up the head I decided to get it checked out and the valve replaced. The previous owners
did absolutely nothing to this vehicle Maintenance wise.

 

My partner just bought a clean 2008 mini cooper clubman s with 49,000 original miles this exceptionally clean car
had a burnt exhaust valve. We was looking to see if the gasket was blown everything was intact. So this one is also in
the shop getting checked out.