Sam, I'd use a nut rather than a bolt. Then, see what will fit on there (nut AND socket) before you weld. You'll have to use a high heat setting on the MIG, and pull away before you melt thru the outside hex. But this is also great directed heat in the bolt.

I wish MB made less use of the allen bolts. I disassembled 2 transmissions this summer and made 1 good one. The B1 reaction pin retainer has a M12 allen hex in it. I had a huge struggle with BOTH of them. The only thing that worked was striking the periphery of the bolt head with a cold chisel sharp enough to catch, but dull enough to not cut easily until it bit in, then continue to strike until that part of the retainer was nearly cut through.

Good luck!

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

I don't think its physically possible to get in there and do this, but, I offer it as a possibility:

If you can use the Dremel and put a notch on the O.D. of the cap screw and then setup with a cold chisel and a 5 lb. sledge, the combination of shock from the sledge and the instantaneous massive torque developed will probably break the screw loose.

I recently had the displeasure of doing the exact same thing on one of the nuts that secured the stabilizer bar bushing. When looking at the nut, there were no flats whatsoever. In fact, at the top of the nut, the threads of the bolt were poking through.

But, I managed to get a chisel on the side of the nut and got it to bite. I heated the nut as hot as I could get with Mapp gas and then started pounding. Took about 30 shots with the hammer...........additional heat.............and some Kroil..............but..................by the grace of the Mercedes gods..............it broke loose. This was really dangerous because the head of the stud is inside the frame rail and I have absolutely no idea how to replace such a thing.

A photo of this nut is below. The tiny land for the chisel is on the right.

Attached Thumbnails

 

i needed to replace the solonoid in my sedan and of course i couldn't get
any of the three phillips screws to move or the top bolt out of the starter.
i took an air grinder and mirror and ground out the solonoid screws. messy and ugly what it did to the aluminum housing, but it worked. then i put the new
solonoid on with socket bolts. if i have to go at it again, cutting a hole
in the fire wall makes sense. there was one in my 300 w115.

when i put a new engine in my coupe, i used hex bolts for the starter and
socket for the solonoid.

don

Only one way to remove that cap bolt after all this.....
Acetylene torch. #7 welding nozzel and a small flame.
Keep both regulators at 5 to 8 psi.
Heat the cap head ( Cherry red.) this will make it longer and it will undo a lot easier.

Replace with new bolt.



.

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

Sam,
You asked if a mechanic would get po'd about a labor only job - the mechanic I usually go to probably would do it. Their shop rate is very reasonable as well. The shop is European Performance Auto. They are located on Mark Sharon Court off of Bayless. They are Rumanian (sp?) brothers who immigrated here - they know Benzes like the back of their hand. Tell them that Amy with the crazy 240D engine conversion project sent you. They did a few labor-only tweaks after I finished my engine swap that got everything tip-top.
BTW - does your silver wagon have a large Biodiesel sticker in the passenger side rear window? If so I think I passed by you earlier this week. Good to know more alt powered benzes are in the STL area. I looked at your web page - I am a friend of Maud as well... St. Louis is such a small town.

FYI, there are tools to remove stripped bolts - sears has them too. they look like a regular socket except inside is a twisting tooth design that cuts into the metal while getting tighter. They work on anything really- great for studs, bolts, allen heads. etc. They have saved me many times. If you get the Craftsman set, be sure it is the set designed for 3/8 drive, not wrench.
I just used one to take out the bottom bolt on my starter since a previous mech had fully stripped it.
worked like a charm.

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00952160000&subcat=Taps+%26+Dies

__________________
Feelstranger
My Wheels
1991 Audi 200 20V Avant
1991 VW Westfalia Syncro/Audi I5
1983 Mercedes 300D turbo
1972 Kawasaki H1 500 Mach III
1970's Limongi/Campy road racing bike
1942 Old Town sailing canoe

i have never found a bolt that I couldnt get off with a chisel and a hammer. hammer the chisel into the bolt head to make a notch. Then hammer away at the chisel till the bolt turns. Heat it up with a blow torch first. these ideas might not be possible due to lack of access to bolt. sorry if I spelled chisel wrong.

I just took out the transmission of one of my '80 300 TDs to make room for a rebuilt. I had better luck than you had; I got that bolt out with two 10" extensions with a universal joint between them.

Heat can be a great friend in breaking things loose, but it pays to apply the heat in the best place. The best thing to heat is not the bolt, but the part it's threaded into. This is because heated parts expand. We don't want the bolt to expand. The ideal would be to cool the bolt and heat the aluminum it's threaded into. This is probably impossible in the space you're working in. So I would try to heat the front quickly and apply torque quickly while the aluminum is hot but before the bolt expands. In your situation I think I might grind away the stripped head.

For working from above with battery, tray and heat sheilds removed, transmission dip tube loosened and moved out of the way.:
Get a new nice hard allen wrench and cut off a piece about 1 1/2 inch long. put the best end in the allen bolt and slide a six point wrench over it so that the head of the wrench is right up against the bolt. Put a pipe on the end of the wrench. Use another wrench or whatever works as a lever to apply pressure to the back of the allen stub to keep it fully seated in the bolt. Curse as needed and loosen the bolt. If this didn't work, I would probably come straight at the bolt from the end (since you have a hole in the floor board) with a drill bit slightly larger than the head of the bolt. Maybe drill larger and larger pilot holes first to be sure it is centered. All you need to do is remove the bolt head. At least you can get the starter out that way. Much easier to remove bolt from starter when starter is in a vise on the bench.

Sam,

You have a PM.

Tom

__________________
1993 300TE
1984 300D
1984 300SD
1976 BMW R90S

Thanks for the reference. I've never actually taken my Benz to a mechanic, and eventually it may be necessary, and its good to know where a good one is! I've also heard good things about GLB Motorworks, on Big Bend, but I've also heard they are expen$ive (every time I drive by I see a bunch of Jaguars, BMWs and shiny Mercedes in their lot).

And yes, that is my wagon! St. Louis is a pretty small town, I'm getting to know quite a few mercedes owners. I've only seen one wagon in town that belongs to someone I don't know, and there is now a 240D in my neighborhood that I need to meet. What does yours look like, maybe I'll recognize it?

peace,
sam

__________________
"That f***in' biodiesel is makin' me hungry."

1982 300TD Astral Silver w/ 250k (BIO BNZ)
2001 Aprilia SR50 Corsa Red w/ 5.5k (>100 MPG)

This problem is solved!

I just wanted to post a conclusion to this for the curious/searchers out there.

A forum member in Illinois (I'll let him reveal himself if he wants) heard my tale of woe and offered to help me out. His workshop is great, with a big mechanical lift, a good set of tools, and a urinal right there in the workshop. Handy!

We tried conventional methods of removing the bolt, heating with a torch, etc. After those methods failed, we removed the air cleaner, battery and tray, the heat shield, and the transmission dipstick.

From there, we were able to get in from the top with a 3" pneumatic cut-off grinder. We used the grinder to chop off most of the bolt head, as much as we could get off without nicking up the bell housing too badly, and then we used a chisel to wack the rest of the head off. After cleaning up the remaining metal a bit with the grinder again, we fed a long punch through a hole in the firewall up against the remaining bit of metal on the bolt head, and give it a solid WHACK, which broke it free, and allowed us to remove the starter.

With the car on the lift, we were able to turn the steering wheel to the hard right, allowing us to remove the starter without disconnecting any suspension components. You have to pull the starter forward, invert it, and then it can be brought forward and angled to the right as you remove it. Assembly is the reverse of disassembly.

Interestingly, when removed, the stud of the top bolt could be unscrewed from the old starter by hand. The fusion was all galvanic corrosion between the unthreaded shaft of the bolt and the bell housing. Whoever installed the starter neglected to use anti-sieze compound, apparently.

The old bottom bolt was reused as the top bolt, since it was in good condition, and we used a basic 12mm hex bolt as the bottom bolt. Its not the perfect bolt, but it'll work. Yes, we used copious quantities of anti-sieze compound on both bolts!

Removing the old wiring actually cracked the cover of the old solenoid as well, so that old thing was really taking a beating, between the punch and so on.

The reassembly went well, and after a while, we had it all put back together without major incident. Upon testing, the new starter turned the engine over faster than I thought possible, and it was started before I could even listen for an entire crank cycle.

I had originally intended to install a good used starter I bought cheap, but after realizing how difficult this project was, I went ahead and bought a new/remanufactured unit. I found a new Beck/Arnley starter on ebay for 65$, so I picked it up for install. I'm glad I did, I do NOT want to do this job again for a long long time.

The lift made things vastly simpler, and I'll be buying one soon (oh wait, I don't have a garage, nor do I own property... Well, maybe someday). Plus, I can't emphasize how valuable the help was. This forum is filled with great people, the kind of people who offer to spend 4.5 hours with a complete stranger helping them fix their car, and that is something to be proud of. I couldn't have done it without his help, and we've even got some ideas for more projects for the future (boost controllers for both of our cars, for instance).

peace,
sam

__________________
"That f***in' biodiesel is makin' me hungry."

1982 300TD Astral Silver w/ 250k (BIO BNZ)
2001 Aprilia SR50 Corsa Red w/ 5.5k (>100 MPG)

That's great news Sam.

Nothing like a proper lift for a problem like this. I can't fathom trying that solution while laying on your back.

Glad it's all back together.

As of this posting I am on my millionth try to get that top 10mm bolt out. I will forego any replication of frustrated attempts, but the following technique worked fine for the bottom bolt and tomorrow if it doesn't rain again I shall attempt the top bolt.

After securing a 10mm Allen wrench with a fitting and extension, I interfaced it with a 6 ton hydraulic jack between the ground and the extension. From a fairly safe distance I began to apply pressure and the bolt loosened immediately. Hopefully I won't have to drill a large whole in the chassis ( hadn't thought of that , but the idea has merit) and I hope to retain the necessary patience to not resolve to heavy artillery, but I am determined to get that top bolt loose.

More later, Leon

Folks, while reading the starter R&R threads and the amount of torque required to break the bolts, I reckoned that the factory used some sort of thread lock. No way you would TQ bolts that size to over 100 ft lbs. Anyway, I hit the starter housing with a bit of heat where the bolts thread into and SHAZZAM they came out without an extended breaker bar, only a "S" shaped 17mm wrench.

This on a '96.