Wish I wasn't posting this but it happened. I would say that I carefully drain it each winter but obviously I didn't do something right. I have fond memories with the family on this boat. I always drain the two plastic plugs under the risers, both block drains, and the water pump. I also run a zip tie in and out of the drains to make sure all water comes out. The crack is T shaped just below the dipstick tube where yo see the water stains. Any chance of a JB weld or something, or is it toast?