C230 Kompressor valves burnt
I am looking at purchasing a C230 Kompressor - 1997. I have discoverred that this car had its valves burnt at a milage of about 170,000 kms. How do I determine that it has been fixed properly as I suspect that the only way that the valves can burn is from a too lean mixture. Is there any tests that I can do to confirm that there is no longer an underlying reason which lead to this problem in the first place.