I was changing out my starter on my 1983 240D. Everything was going smoothly until the last, top 10mm allen-head bolt. It would not budge. I used a 10 mm allen head socket with a cheater bar and it would not budge and began to strip out. It actually felt like the socket would snap if I tried any harder. I soaked the area with penetrating oil and was working with a cool enginge. Would it be better with a hot engine? Would hitting the bolt with a torch help or cause more damage? I saw the idea of valve lapping compound but I think I am beyond that stage. There is some room between the fire wall and the bolt, but the room is limited. HELP?

Darryn

Try forcing a 12pt(metric) socket over the outside diameter of the allen bolt. Use the starter bolts that you have already removed as a guage. The 12pt (metric) socket MUST be forced / made to fit over the allen. Use a good quality socket (snap on / craftman) that will withstand this "hopefully" one time abuse. Get new bolts all around and Voila!

__________________
Regards,

Albert
aldedmon@yahoo.com

I had a similar problem with the allen bolts on my vacuum pump. I was able to get a set of vice-grips in there and by using max closing force, I made the bolt turn. Properly secured, a set of vice-grips can apply a great deal of torque.

Nic
'85 300CD

Cover the allen key/socket with a paper towel and then stick it into the allen head. The papertowel provides just enough fill to take out any slack that could lead to stripping.

I did this with the filler to my differential that hadn't been moved in 20 years. With just the allen socket, it would have stripped, using the paper towel, I used a 2 foot breaker bar and pushed it with both feet and it came loose without stripping.

Good luck,

JCD

Dlduchon,

Heat works miracles on stuck bolts. If getting the engine hot doesn't work, try a torch on the bolt head. Try to get it red hot and apply torque quickly with the allen wrench.

If that and the other suggestions don't work, you might have to cut off the bolt head with the torch. Have a fire extinguisher or lots of water handy in case of a fire.

If you cut off the bolt head, arc weld another bolt to the remainder of the stuck bolt. The heat from the welding should get the bolt hot enough to come out.

One other possibility is to arc weld your allen wrench to the stuck bolt. The heat should allow the bolt to break free but you will have sacrificed your allen wrench but they aren that expensive

That's what I would try to get it loose.

P E H

PEH, you are sure right about heat, on bolts the size of starter bolt you can do pretty good job with simple torch from hardware store if you dont have a welding torch. I often strike a frozen bolt on the side of it's head with a cold chisel after heating sometimes a bolt that will break a socket will come off with a with ease after heat.be real carefull not to start fire...........

William Rogers........

Had the top bolt on mine start to strip out when I did the starter last year. Here's what I did:
1.Remove air cleaner, battery and tray, anything else in the way. This bolt is easier to remove from the top.
2.Loosen dip-stick tube and push it out of the way.
3.Use a very small screwdriver and make sure there is nothing in the allen hole of the bolt.
4.Take a good hardened 10 mm allen wrench and hacksaw off a piece about 1 1/2 to 2 inches long. Do a nice square job or dress it up on a grinder. You are going to want those nice, sharp edges on the cut off end.
5. If you can get to it, bang on the side of the bolt head with a hammer or such. May help break it loose.
6. Hold a long handle 10mm wrench in front of the bolt head and slide thecut off allen piece thru the wrench and into the bolt. Do whatever you have to to force it ALL the way into the bolt and make sure it is straight in. If need be, you can slide a pipe over the end of the wrench for more leverage and perhaps use a prybar to push against the end of the allen to keep it in the bolt.
7. now you should be able to pull up on the wrench and with luck the sharp edges of the cut off piece will hold against the remaining good metal of the bolt. just remember to keep the wrench tight up against the bolt head. This really helps to keep the allen from tilting and rounding.
8. Good luck and let us know how it turns out.

Dlduchon,

Did you ever get the stuck bolt loose? If so, tell us how.

P E H

I have not had time to try to get to the bolt. Thanks for all the help, I have been using all the ideas given to formulate a strategy for my weekend bolt removal project. I have been unable to find an extractor that will work. I have been drenching it daily with liquid wrench. I also noticed that the other end of the bolt is visible under the aircleaner and manifold. I am going to give it a few good whacks from the back end. Last resort will be to take it to a welding shop and have them weld the 10 MM allen head socket to the bolt and when I get it loose cut it off so I can pull it the rest of the way out.

Darryn

Don't hit it too hard from the opposite end. You will damage the threads and then damage the internal threads when you screw out the bolt.

Try heating from the opposite end if you can. Even a Bernz-o-matic torch may work. Heat works wonders on stuck bolts.

P E H

I got the bolt out. It was fairly stripped, but if inserted a 10mm allen socket all the way it had some decent grip, enough to move the engine on the mounts. Pounding a socket over the top was going to be nearly impossible, no room. I tried heating the starter with an acetylyne torch, since it is the only part that the bolt screws in to. I thought it would expand and release the bolt. I tried it about five times with a friend on the torch and me on the bolt. It did nothing, would not budge. I tried pounding it. Nothing. I tried liquid wrench, no movement. We heated the bolt head with the torch for about a minute, my friend advised against it thinking it would expand the bolt and make it worse. However it popped right out with minimal effort on the first try. Amazing. My advice is if it does not come loose with some reasonable effort on the first or second try stop until you can heat the bolt head with a good torch. By the way, it was much easier to remove the starter from the top than the bottom. There is practically no way on a 240D-auto to get it out from below without removing a lot of steering parts. I just loosened the brace to the manifold and the bracket for the heater hose after taking of the air cleaner and pulled it right out. Contrary to the manuals, you must also remove the back bracket to get room to pull it out. Don't forget to take the rubber plugs out of the screw holes in the back! I did and had to remove the bracket again. I, of course, replaced the bolts and the washers (with mercedes parts) for a few dollars.

Darryn,

See, I told you heating the bolt would work. Somehow it breaks the solid state diffusion between the bolt threads and the threads its screwed into.

I know it seems logical that the bolt would expand and get tighter but thru experience I learned that heating works to free stuck bolts. It works even better on stuck nuts where they do expand.

P E H

When you heat the bolt it does expand,,,and crushes the corrosion between it and the nut... but I usually let it cool... and then use penetrating oil... with more space it can get in easier..old tractors left outside with huge bolts and nuts need these types of physics regularly...

Remember that should any other attempt fail you can still weld on another bolt, or a piece of steel on the bolt and have it removed this way, always worked when everything else failed. No acetylene torch needed, CO2 works great.

Impact tools are the cat's meow when it comes to removing stuck and even stripped bolts. Use one along with any of the other suggestions.

--any except Jassper's C02 suggestion. I'm not sure how you can use carbon dioxide (mehbe dry ice??) Care to elaborate Jasper?! (keep in mind I live under a rock) Also there is the risk that Gore will charter a 747 from his mining facility and then chase you down in a convoy of SUV's and ask you not to emit so much C02 if you try this technique


...I'm going to exhale on all my stuck bolts-nope, that didnt work. oh wait! my breath has desolved a bolt! oh sh-t! here comes gore! I better put my breath in a 'lahhhhck bahhhx.'