I have posted in the archives my description of cleaning my 123 1980 tank... taking it out and to the car wash to pressure clean it.....
I discovered that it had enough large holes placed to where I could spray easily and I would not take it out again to clean it... but do in the car.... I do not know about your model though..

__________________
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