Yesterday AM I was trying to align timing marks to check a no-start condition ... forgot to remove breaker bar from crank pulley bolt and turned over engine:



From FAQ:

[Caveat re: Timing Pulley Failure [Tip from Tom Irwin:] Here one problem to watch out for... B230 lower timing pulleys have a little 'nib' extrusion that does the work of a keyway/shaft. It is a cast part and it is delicate. In the old days we used to fix a large socket and breaker bar over the pulley bolt, wedge it against something solid and whap the starter over to break loose the bolt... DON'T DO IT! That little key/nib will break off or weaken so it breaks later and ALL your accessory drives (alt/ps/ac/etc) stops spinning. Oh yah! that little chunk o'metal is special order and about a hundred bucks! Any bolt removal technique that relies on "whapping the starter", jamming the ring gear, or using an air wrench on the center bolt, may cause this key to break off. Get the right tool (Volvo 5284) and restrain the pulley

http://www.brickboard.com/FAQ/700-900/EngineSealsBeltsVent.htm#Changing_Timing_Belt_Bolt_Removal

The good news is the part can be ordered from FCP Groton for $35, as of July 2008.
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Big Swede: 1989 745T 234,000KM