I have a marinized OM636 in my yacht and in the process of rebuilding the engine I have discovered there is no ball pins in any of the pre-combustion chambers.
Does anyone know what type of pre-combustion chamber should be put into the head #636 016 1301 and the likelihood of the ball pins burning out in all 4 chambers?

If you have one of the service manuals for the OM636/621, this information and the differences between several types of MO621 engines is available there.. Often the specific p[art numbers for variations will be found in there as well.
Good luck! You can find these manuals on Ebay, I have. Expect to pay between 25-75 for the factory service manual, often with many useful TSBs in there as well.

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Strelnik
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We do have a Service manual for the OM 636/621 engines. Its a very early copy. It states there we 5 different versions of pre-combustion chambers up until the time the manual was printed. I have found a number of changes with parts on the engine that are not in the manual.
I was wondering if there were more versions that did away with the ball pin as there are none in any of the chambers. I was hoping to prove it was not due to pin burn up!