Tips on broken bolt removal

[DFWtechie]

I had a bolt that was broke on Motorhomes exhaust manifold causing and exhaust leak. I removed the manifold and when I drilled it out the damn bit broke off inside the bolt. I had to do this to 2 others as well but didn't have the bit break off.
Any tips on how to get it out now since the bit is in there? Any special bit that can drill that out?

[Sean88gt]

You could try a reverse bit, but I'm not sure how they work with existing drill bits.

http://www.jalopyjournal.com/forum/showthread.php?t=644083

Read through that.

[JimD]

Tool steel is a motherfucker to drill out, how far down it broke off?

[RuStYpNuS]

You MIGHT be able to break the bit with a center punch and hammer. Typically the harder the metal the more brittle it becomes. I highly doubt that easy out is made of tool steel. I'd bet more on cobalt or HSS. Tool steel is typically used for cutting tools like whats used on lathes isn't it??

Regardless try to hit center on it and worse case buy a few cobalt drill bits. Drill slow and steady and keep the bit cool and youll get through it.

[dee]

A welder with some surface harding rods work really well.

[DFWtechie]

the bit is about 1/2 inch down in the hole. I was drilling thru the bolt to get lube in behind it to try and loosen the rusted bolt. as soon as it broke thru the bottom it snapped off. It was brand new Milwaukee drill bit. I am gonna try the reverse bit thing and see where that gets me.

If I could weld it I would but the bit is to deep in the hole.

[dee]

Why can't you weld the broken bolt and remove it all together?

[DFWtechie]

it was broke off flush with the head.

[dee]

All you have to do is build it up a little then weld a nut or washer and nut to thr built up part.

[shumpertdavid]

dee's idea sounds pretty promising if you have good clearance. Aside from that, the ONLY thing I've managed to cut on a decent drill bit with is the diamond tip cutters from dremel tool. They come in a 2 pack, one will be a little ball ended cutter, the other a long round barrel type cutter. It could take you several of the ball style to eat enough away to do any good. I usually try and cut around the bit of easy out as the bolt material will be softer. I've been in your same situation a couple times and it's very frustrating.

http://www.homedepot.com/p/t/203362662?catalogId=10053&langId=-1&keyword=dremel+diamond&storeId=10051&N=5yc1v&R=203362662

[jyro]

x2

Why can't you weld the broken bolt and remove it all together?

thats sometimes the best way to remove a broken bolt, weld a nut too it. Ive found on those motorhome exhaust manifolds( I've had 3 now), you get the motor hot from running it and break the bolts loose with the motor hot. I've been lucky and never broken one yet. as for the replacement gasket, do not use anything but felpro blue ones, they run about 30.00 for 2 but you won't be redoing it.

[DFWtechie]

Jyro, that's how this started, the bolt I am working on the reason I had to remove the manifold. I ran the motor for about 30 mins and go all the bolts with the thread extensions on them out no problem. The only 2 that had regular bolt heads broke off. I got those out but then when I went to get the initial bolt out this happed.
All I know is I have been tackling this for 3 days. And this did not have a gasket on it which had me a little confused. But it is was only leaking where the bolt was broke.

[jyro]

from the factory, no gaskets, normal. the lack of air in the engine compartment causes the exhaust to overheat and warp. there is a mod that uses sheetmetal to redirect air from below to the engine exhaust but i looked for it online and found nothing. If you can lay a nut over the hole with the broken bolt in it ( and now drill bit), fill the hole with weld starting from the broken bolt to the nut, it may take a few trys to get it to break loose, let the metal where it's welded cool before you try to turn it.(there is special rod for this also) last resort is a dremel with a carbide or dimond bit and a helicoil likely. I know it's not a fun place to work up in that wheel well

[UserX]

All you have to do is build it up a little then weld a nut or washer and nut to thr built up part.

This is your best shot, at least for removing it without any thread repair needed.

[jayjohnson600]

A couple ideas that have worked in various situations, when I didn't have a bolt extractor.

Sometimes a busted bolt will come out easy, some light taps with a tool, see if it will come out with pliers, only moderate force. Spray some penetrating lubricant on the threads, wait a couple minutes, try the pliers again.

For tighter bolts
Use a small drill bit, drill 3 holes in a line across the bolt close as you can.
It can be important to get the first hole centered well. You may need to plane the surface flatter, use a punch marker to make the initial dent for drilling.

Now you get to use experience and judgement.
You can tap a flat head screwdriver into the 3 holes. Spray some penetrating lube on the threads and unscrew the bolt out.

Or, you can use the 3holes as a good grip edge for welding the bolt to a nut.
Wait until it cools most of the way, spray some penetrating lubricant into the threads, then put a piece of ice on the nut to help shrink the nut and bolt while the block/boss is still warm.
Unscrew the nut and bolt.

Lastly, you can center drill it, short of the threads(check size by inserting bit into another bolt hole), then use a flat head to tap one side of the bolt threads into the center, insert a screwdriver so it's wedged against the edge of the threads and lightly tap out. Little, if any, thread damage if done carefully.

Good luck.