you may not have to remove engine,it depends where the crack is,if it is in an accessible position then you could try draining oil overnight,get the area very clean and rough up the crack with emery or a file and try a magic metal repair,some products are very effective nowadays. Not sure if your sump is pressed steel or an alloy and using an appropriate welder for whatever you have is another option.Both could save you a load of time and money depending how bad the crack is of course.
cdc, May 2012