Steve is right - something caused them to break. Before you get too much "exploratory" money tied up in it you may be better off picking something like this up. Probably not a bad price.
Check it out.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33615&item=2450838254
Do contact them before you bid to confirm the correct engine. The one pictured IS NOT a 1983 240D engine but that may just be an error in putting it on ebay.