I have posted on a several threads during the past few months as I went through the various steps of diagnosing the problem (engine failed to start after reconditioned head fitted)

The title includes the OM606 as the 605 is the same less one pot.

I am glad to say that it appears I have finally found the cause of the issue after exploring many options and now need advice on how to proceed.

There's quite a bit missed out as its on assorted threads but in essence stuck rings were suspected so head pulled followed by sump to gain access big end journals.

Ok, first piston is out - needed a small tap from underneath to get past carbon residue - as I did this and the piston released I felt something drop on my head, it looks like a piece of the oil scraper?

It was quite a gentle tap and unless these rings are very fragile its been like it for some time, I suspect this is what has caused the scoring on number two cylinder (this is number four).




Ignore the scoring on the middle of the crown, this is very light and my last attempt at jiggling the piston back and forth to free the rings.





Bore looks good;



Here's the main problem (apart from the above) the top two rings are completely flush with the side of the piston, no wonder she wouldn't start!




This looks to be where the ring joins, as can be seen it's fully compressed;



My plans were to hone the bores and replace the piston rings with a standard set but I would be interested to hear any other suggestions before going ahead.

If anyone has a OM605/6 and needs a bit of help I have taken a few photos along the way.

__________________
David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)