Be sure to read the threads about that reaming...

many people assume that you can just use the engine to blow out any carbon which might not have been captured on your heavy greased threads or vanes of the reamer...
but that is not the case.... since half the time your piston is sucking. and if you do not pull the precombustion chamber in this process ... then the potential for where that loose carbon will GET STUCK is the precombustion chamber holes... radial tiny holes which are the essence of your whole diesel physics.... I think there are 7 of them on most of our engines... like many things they did change some things about them....like the size on the ' uprated' engines...
And if you take out the precombustion chambers remember this part is critical...
take out the glow plugs,
take out the precombustion chambers,
put the precombustion chambers back in,
put the glow plugs back in.

VERY IMPORTANT CONCEPT.... otherwise you cause real damage when you shear off the end of the glow plug while moving the precombustion chamber.... LOL

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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/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

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