You might want to post this in the Vintage section. The answer is no, you don't need to pull the engine. If you are going to pull it anyway, it certainly would be easier to do... Some of the other guys might be able to help you out, I had mine done right after I got the car - now I'd probably do it myself. It might take a few days to get an answer, as last weekend was the International 190SL Convention in Leadville CO, and many folks haven't arrived home yet! You might also try posting a note on the 190SL formum (
www.190slgroup.com).