If it's all the way through you definitely need to fix it. Remove it and clean it up (a dremel-type tool will help) and then patch it with some JB weld, both inside and out.
At least you'll have resealed it to the valve cover when you're finished so that won't need to be done for a while.
Good luck.
At least you'll have resealed it to the valve cover when you're finished so that won't need to be done for a while.
Good luck.