Recently had the same probem with my '88 240. Tried it, but it was a pain in the butt. My mechanic replaced the timing belt and it was ready in two hours.
Cost = $145.00 USD. I felt that it was worh the money to have it done. AAA+ towed it to the garage for me - part of the membership. Good luck!
I was struggling with removing the bolt for the lower crank on my 1991 740, after doing the head gasket last week, and came across a thread that suggested using a breaker bar lodged against the left side of the water pump. You the tap the starter and voila (or the Swedish translation of voila) the blot is loose. I was concerned about damaging the water pump but I tried it and it worked excellently. I had a cheater bar on the breaker bar to prevent any injuries, and had my son tap the starter. the bolt broke loose immediately and the pully came off with a few taps. Check the location of the crankshaft when reinstalling. There is a thin washer that has a cut in it and that cut is what alignes with the 11:00 mark on the block. Then line up the other 2 pullys and install the belt. Also be sure to pin the spring loaded tensioner with a nail or a drill bit. It will make reinstalling possible. I loaded up the spring (after only loosening the tension bolt) by using a pry bar and then putting in the drill bit in the hole in the shaft. Then you take apart the assembly and R&R the belt.
Hope this helps. I was able to do the job in about 45 minutes after the 3rd or 4th try to get it right.