I doubt it will stop cracking.You mite want to try to find the extent of it and drill a small hole at the very end of the crack and put a rubber plug in it to stop the progression of the crack.Sooner rather than later you will need to weld it up.
Drilling a hole stops cracks on supersonic jets. Fill it in with epoxy of choice or silicone goo of choice.
Would by my first course of action, too. Drill and a tiny smear of JB weld.If the crack continues to expand somehow after that, then you can take it to a welder. Even if it holds, you can get it truly welded up next time you have the cover off at a convenient time, if the first fix just bothers you for some reason.