Replacing the water pump in 95 s320. I got three of the four bolts out but rounded out the bottom front allen bolt. So, I am contemplating how to extract the bolt, its pretty tight in there with the PS pump still attached.

My first thought is to drive an oversized torx or allen bit into the head of the bolt. Maybe paste some jb weld around the bit and bolt.

Second thought would be to remove the PS pump and see if I can get a Sears easy out bolt extractor on the bolt.

Third, would be to get someone to actually weld the allen wrench into the bolt.

Fourth, would be to use a dremmel to slot out the head of the bold and see if I can turn it with an oversized screw driver, or grind off the head of the bold alltogather, remove the water pump and get some vice grips on the shaft of the bolt.

Anyone have any other ideas or suggestions on which of these I should try first?

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jayhawk

Hi
Same happened to me, although on a M103 waterpump, and it was the lower rear one. I was successful using a left hand spiral, tapered flute. See also the following link.
http://www.peachparts.com/shopforum/showthread.php?t=144856
Good luck, Bruno

I tried JB Weld on the fan clutch bolt... didn't work.

Don't know how much room you have or can make but... drill it out till it falls off... it should be easy after that.

Oh and don't forget to order your new bolt now!

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-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14

That would be my vote.

OK - I'm pretty sure I can get a drill bit on it. I just picked up the new $5 bolt today, it took a week to get.

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jayhawk

Another method to consider.... try grinding the head off the bolt with a dremel. Once the water pump slips off you can perhaps deal with the stuck bolt a little better since there's some length to work with.

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95 E320 Cabriolet, 169K

If you can pound a 12 point 12mm socket onto the head of the stripped out allen bolt you will be able to loosen it, it will grab the outside of the head goodentight JA.

A 3/8 drive would be best...............

IF that does not work, try prying the water pump away from the block and rotate it at the same time, this action will loosen the bolt.....!!

Bruno - How do you use the screw extractor. Do just drill it reverse direction into the hex bolt? Or do you drill it in and then put a wrench on it? I can't picture it breaking the bolt loose with just a drill.

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jayhawk

jayhawk
I put a 1/4 inch hex socket on it - but the other way around: with the square female on the square male of the extractor (which, obviously, happened to be 1/4 inch too). Then I put an allen socket in the hex socket. Then you can put anything you like (universals, extensions, ratchets etc.). I do not know whether there may be square sockets available that would directly fit. I did not use a drill at all.
Bruno

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1992 300TE 160 kmiles

OK - So the extractor bit just bites into the stripped bolt with enough grip to break it loose with the torque of a rachet?

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jayhawk

Ideally they do. Especially allen heads are suitable because they already have a hole in the center where the extractor can catch.

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1992 300TE 160 kmiles

If you can access it from the side you can try to tap it loose with a long thin chisel and a hammer. First make a dent in it from the front then put the chisel in the dent from the side (or front/side) and hit it with the hammer. Try to avoid hitting expensive parts or your hand.

Thanks for ideas. I am going to tear into it this weekend, I'll let you know how it turns out.

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jayhawk