So to make a long story short.. the top left valve cover bolt hole somehow stripped out. I started to see it seep a little bit from the top of the bolt, (not from the valve cover gasket). It was loose and it will not tighten up. When I popped the bolt and shank out I can see some of the threads are pulled out. I currently have the right helicoil kit at my house. In theory could I drill and put the thread insert in without removing the valve cover? I can fit the tap, insert tool, and drill bit in there just fine. I figured if I put a bunch of grease or antiseize on the drill bit it will help hold the shavings to it if I drill in small increments and wipe it off. I'm very strapped for cash so I can't afford the new parts it would require to remove the cover..