Stripped Allen Bolt - PeachParts Mercedes-Benz Forum

jayhawk · #1 03-09-2006, 03:07 PM

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?

Bruno_300TE · #2 03-09-2006, 03:17 PM

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

A264172 · #3 03-09-2006, 03:17 PM

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!

Ron in SC · #4 03-09-2006, 03:20 PM

Quote:

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

That would be my vote.

jayhawk · #5 03-09-2006, 03:32 PM

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.

Kestas · #6 03-09-2006, 04:45 PM

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.

MrCjames · #7 03-09-2006, 05:31 PM

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.....!!

jayhawk · #8 03-10-2006, 10:52 AM

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.

Bruno_300TE · #9 03-10-2006, 11:12 AM

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

jayhawk · #10 03-10-2006, 03:58 PM

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

Bruno_300TE · #11 03-10-2006, 04:13 PM

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

Rob Pruijt · #12 03-10-2006, 04:21 PM

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.

jayhawk · #13 03-10-2006, 05:03 PM

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

cudaspaz · #14 03-10-2006, 09:28 PM

I have ran into this many times.

Thats why you replace the bolts with compatible 13mm hex head bolts for the next guy when the water pump seal goes bad again.

I use a spline drive socket on a 1/2 inch drive long(wobble type) extension (not universal )type and pound that sucker in there with a Big hammer. (Power steering pump unbolted and moved back away, lines still attached.)
I also apply a little bit of valve grinding compound on the end of the spline drive socket, that keeps it gripping and not slipping.

It works every time, just make sure you use the right size spline that will fit into the hole snug,and don't be afraid to whack that sucker in tight with a hammer.

Remember, auto parts stores let you borrow tools.

make sure you replace all the bolts with the right length metric thread bolts with a 13mm hex head and use wavy type lock washers.

That's how the old man taught me how to do it.- Works every time.

jayhawk · #15 03-11-2006, 08:16 PM

Thanks guys. I ended up getting it out with an oversized torx bit today. I already had the new 6mm bolt so unfortunately I did not get to put in 13mm. It was tight but I tapped in the torx bit and it broke the bolt out. When it broke, I thought it had just stripped further but I looked down at it and the bolt was turning. I had to remove the PS pump and move it to the side. I probably should have done this to begin with. But last post is right, after looking at the other bolts I wish I had replaced all of them because they are all a little rounded on top.