6mm hex bolt is hexed
 

I am three weeks into replacing a water pump on my 190e and have removed all but one bolt. The remaining bolt is the top front 6mm hex bolt. I cannot securely place a 6mm key into the bolt and have no idea what the problem is. Therefore, my question is obvious. What is the best approach to remove this bolt if the proper tool is useless? I am so close, yet so far.

thanks,

john

can you fit a ball end Hex in there?

Does it not go in far enough? Or is there slop? I've heard of some people dipping the bit into scouring powder (Ajax,Comet, etc) for extra grip.

Put the other bolts back in and tighten them down. No sense in trying to free the hardest bolt to remove after the other bolts have been removed,,,,

Make 100% certain that ALL THE CRUD is out of the hex head, otherwise you'll strip it,,,

Use my favorite new tool - the Dremel with a grinding bit.

Game, set, and match!
 

I got it off by wedging in a 6mm and praying. The new pump is back on. Tomorrow I put everything back together. Maybe it is not match yet, but it is close. Thanks to all for your help.

jbadgio, recommend that you buy a new 6mm allen bolt from your local MB dealer before you install the new water pump ... to avoid problems the next time around.