Originally Posted by ah-kay

I resurrected a 190D OM601 engine with low compression in cyl 1, also < 100psi, by doing the following.

1) removed head.
2) removed oil pan and pushed all pistons out from below.
3) honed cylinder 1, cleaned ring grooves, load of carbon, replaced rings.
4) It bought the compression back to > 300psi ( cold ).
5) The compression on the other 3 cyl are OK but I cleaned the ring grooves anyway.
6) Now the engine runs like a champ.

I am not sure how easy to do it with a OM616 but you may be in luck as it is cyl 1. It may be possible to push the cyl 1 piston out by removing the lower oil pan only.

Good luck.