Ughh...snapped timing cover bolt...
 

While resealing my w124 timing cover for the 4th time with the right seals and RTV, I snapped the top right bolt off that holds the top part of the tensioner damper bracket to the cover when putting in back together. The bottom right bolt is doing a good enough job sealing the right side and holding the damper. I have tried every drill bit and hardened tap drill I had and cannot drill a hole into the bolt to get the tap in to twist it out (two drill bits broke). Is there a special, sharper bit, I need to use on these bolts? I went to sears and bought a Micro-Bolt remover set that didn;t do anything. I only have about 1.5 mm of the bolt sticking out when the cover is off...ughh :( I'm thinking about just clamping the top part on somehow.

That's pretty odd. Usually when such a bolt no longer has any pressure on it (from being tightened down) it will just unscrew easily by finger or with pliers on the exposed end.
If I recall, without looking, doesn't that bolt thread into the aluminum head? The torque used on that bolt is only about 25 ft/lbs, how could you have possibly tightened it enough to snap it!? I would think the threads in the head would strip before the steel bolt would snap.

Yes, it does go into the head. I didn't give it that much pressure either...just a wrist tighten with a socket wrench and it twisted right off. I don't have enough end exposed to grab it with anything...

Try a left hand drill bit. If it can grab the shaft it will probably drive it out.

I will. And also, the toughest and sharpest I can find! Thanks

If its broken off flush can you try JBwelding another bolt to it? I've never done it, but it was always a theoretical option if drilling didn't work.

That is an idea John! I can try that but will JB Weld hold onto something like that with such a small joint? I've never tried. Otherwise, maybe I can just get a titanium drill bit or something...It seems to be holding OK for now. I think I will try to clamp it somehow to the head if I can find a clamp that fits and doesn't look too bogus :)

Is there enough left to grab it with needle nosed vice grips? They come in different sizes and can get into a tight area.

I will try but I don't think so. Gotta be a sharp enough drill to get into that bolt somewhere!

Sharp isn't really what you're looking for, HARD (and sharp) is what you need. Try using a very small, pointed grinding stone with a dremmel, foredom, or small drill (a red or white stone rated for glass work or hardened metal) to start the hole.
First, a few important points. You need to have the hole as accurately centered as possible, so grind (or file if possible) a flat on the exposed bolt surface and then use a center punch to mark the drilling spot. Use a left handed drill bit with a reversible drill. Using a standard direction drill can tighten the bolt even further. Use as small a drill as practical to start and enlarge the hole as necessary with successively larger bits. And lastly a slow speed high toque drill is best, A fast drill in hard metal will overheat a bit quickly.
Once you get a hole started with a stone, switch to a hardened metal rated drill bit (perhaps even a diamond tipped or encrusted bit may help). Use a machinists lubricant with the drill bits and pause often to cool the bit (maybe even have a cold cup of water t dip the bit in). If the bit discolors (turns straw to blue) it's been overheated and will quickly dull.
Be VERY careful not to break the bit or extractor off in the hole, then you really have problems.
Don't forget to protect the opening into your motor at the lower cover from grit, debris and metal shavings. When you get a deep enough hole, tap in a slightly over sized easy-out. Then, with a standard tap handle attached try to turn it out by hand. If it feels like the extractor is going to snap, stop! The hole may need to be enlarged for a bigger extractor (hence the importance of starting out as centered as possible). I don't recommend using it with a reversed drill.

You can also try a very small diameter, very thin carbide disc in a dremmel or drill, to cut a slot in the end of the bolt to turn it out with a screw driver. This will probably cut a corresponding slot on the head as well. If done carefully, with a small enough radius of a disc, and judiciously positioned so the marring to the head is minimal and oriented to pose the least potential detriment, the marks on the surrounding aluminum mating surface shouldn't cause and problems. This would be a last resort proposition, but I have done it before in other circumstances. Also, this would really only be effective if you expect that the problem with broken stud is mainly just getting a firm grip on it and that from there it should turn out somewhat easily (as opposed to being lodged very tightly, cross threaded or rusted in place).

If all that doesn't work, using a wire welder, the method is to weld a washer (with a smaller hole than the diameter of the stud) to the end of the bolt. If the bolt is slightly below the metal surface, the washer should be peened in the center to make contact and then welded to it. Next, weld a nut that is smaller than the diameter of the washer to the washer. The bolt can usually be turned out with a wrench. The heat from welding also aids in the process by breaking bonds between the stud and the threads it's stuck in.

Good luck.

!
 

Awesome! I have a dremel and didn't even think of it! I have used it many times to do just that and never even thought of it, I knew someone would have an answer here. Thank you so much long-gone! I will post my update when I get a chance to go for it with the dremel.

Steve

Suddenly, I am not feeling confident about doing this job on my car.

Its not that hard. I just tightened the damn bolt to much and snapped it on my third reinstall:( Just use some oil on the bottom u shaped gasket with a cut out plastic slide and it will be a breeze. It was only an hour job that I made into three days by taking it back on and off because I didn't get the gasket on right the first time and damaged the cam seal without realizing it. It is now perfect after reading all of this advice. Just did my fan bearing pulley pracket today. 2 hours and car is now much more quiet than before! You can do it Eric!

Sptt! read the advice again, don't use any oil on the gasket. If you could do that you wouldn't need the plastic piece!

Very specifically, all the surfaces where the gasket will lay must be thoroughly cleaned and the wiped down with a solvent to remove all traces of lubricants.
This is a DRY job with sealant used only in corners, top and bottom, of just the ends of the gasket.
The only lubricant I could recommend, would be some spit or a light swipe of water on top of the gasket to help the plastic slide out. The spit will quickly dry. Even this is only if needed, which is why I suggested a dry run to see what to expect. I didn't have to use anything when did them.

This is a notorious point of oil leakage on these motors and from all I've read, if they aren't done right (procedure and materials) they'll be leaking again soon. Well over a year on one of them and it's still dry.

Also, the dremmel with a stone is just to get a hole started for a drill bit, don't try to bore a deep enough hole for an extractor with the dremmel alone. Also make sure you protect the opening to the crankcase with some clean rags. if you drop any broken bits of stones or a small drill bit, even metal shavings, it could be bad news.
If you're even thinking about cutting a small slot with a carbide disc, it must be done very carefully as not to deface the head! you could easily mar the surface with a slip, so decide to do this with good consideration. The disc is a very small (about 1" to 1.5" diam), somewhat brittle wafer, half as thick as a worn dime. They'll be in the dremmel bit rack at the hardware or hobby store. They want to track away while in use and must be held very still while cutting as they can break apart pretty easy and go flying (wear goggles).