Stripped ETorx bolt M50 Head

[bd92]

I have been attempting to remove the head of my 95 525i with 298k miles. I suspect a bad headgasket and so I have been removing parts little by little over the past few months.

I haven't had much time, hence I get little by little done at a time. Well I am at the point where I have removed all the head bolts and removed all the torx bolts except for one that is stripped. I stripped it, doubt it's the quality of my socket but the wrong angle in which I attempted to remove it. I am lost at this point. I have attempted an E7 but it's too small to fit. I have tried different E8s and none grab the bolt because of how stripped it is. Just the location of the bolt, it's hard to attempt to remove it. I can't think of anything so I figured I'd ask anybody here if they experienced the same thing and what they did to remove it. It's the last bolt holding the head down.

Any advice I would greatly appreciate! Thanks in advance.

[DrCharles]

You'd have to be careful to avoid damaging the head, but the usual "fix" is to MIG-weld a nut to the top of the bolt, then once it cools use a socket to turn the bolt out...

[dannyzabolotny]

Worst comes to worst you could use a drill bit (with maybe an extension) to drill the bolt out, starting very slowly from a small size and working your way up until there's not much bolt left.

[ross1]

There are special sockets made for extracting rounded bolts but they are generally thick walled and won't fit in that recess so you'll need to be creative.
A 1/4" hex socket fits pretty snug on an undamaged E8. If it is too mangled for that you might be able to bang a 6mm hex on it. I've not seen spline drive heads this small but those same sizes if available on a spline drive might work too. A trick I use with troublesome internal hex(Allen) bolts is a bit of coarse valve grinding paste on the bit. It sometimes provides just that extra little bit of grip you need.
The only good news is this a low torque fastener so you won't need THAT much purchase on it. Good luck.