I've recently had OM617 head problems too - mine was a broken valve guide:-

http://www.peachparts.com/shopforum/showthread.php?t=276144

I also asked about seat grinding and got several responses here:-

http://www.peachparts.com/shopforum/showthread.php?t=283999

I hope these threads help.

A summary of the advice:-

If you don't have access to machining equipment - farm it out to those that do. A pity really as I was itching to get some new toys...

EDIT:-

I forgot to say - before you decide to dismantle your head it might be worth your while doing a leak down test - or at the very least a compression test. It might throw some light on your problem

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!