The super safe method is to install an oz or two of Mystic Mystery oil into the cylinder, leave overnight, rotate the engine WITH A HAND wrench.... two revolutions ... then some of these other methods will be super safe... as the chance a ring is stuck the bore has been eliminated...

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html