Use some valve grinding compound on the hex bit, it will help it bite into the bolt.
I use my breaker bar and a 6in extention all 1/2 in drive with the hex socket.
give it a quick pull, and it should snapp free. usually using steady pressure will make it slip. this has worked for me.

make sure the bolt head is cleaned out so the hex bottoms out in the head.

Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works