Not on the OM601 engine I overhauled but on a OM603. There was a lot of coking around the rings and the the same got stuck in the grooves. I do not believe MMO will help with heavy coking. If it is only 100psi then you need to take a look at the cylinder wall. It is loo low to be caused by coking alone. The cylinder wall may have been scored by a broken ring or oval'ed.

Changing the sleeve is a big endeavor with engine out of the car. I left the short block in the car. You only need to hone it slightly to take out minor scoring and imperfection and compression can be restored. This has been my experience on 3 engines, 1 OM601 and 2 OM603.

Good luck.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

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