If it's grinding it's probably damaged. So if you're gonna go to the effort of getting the CV boot off to grease it you might as well change the CV joint (or the whole driveshaft) while you're there. That is if it definitely is the CV joint thats grinding. If you've got a split CV gator with grease all over the place then look no further. CV joints tend to be clicking noise when turning so not sure when u say grinding. Another possibility is the disc brake guard has got bent in and is rubbing. That's an easier fix.