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Discussion Starter #1
I have at least two broken shroud bolts on my M18 Kohler. These are 1/4-20 bolts and obviously very rusted in. My plan is to drill a hole through them with a left-hand drill bit, partially because of the slim chance that the heat of drilling will break them loose and they'll unscrew, and then try to fill that new hole with PB Blaster and let them sit for a few days. After that I'll attempt to get them out with a screw extractor.
Does that sound like I might have a hope of getting them out of there? How about a better plan?
 

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I would just drill them out starting with a 1/8" bit and work your way up to whatever size drill you'd use to tap a 1/4" hole...then re-tap the hole,if the bolt doesn't come out while your drilling it..

I hate "screw extractors" and "E-Z Outs"..few ever have worked for me on anything that tiny--on bolts 3/8" or larger they might not snap off on you,but anything smaller they almost always break off,and present a larger problem to remove them..

I also use the welder on many smaller bolts--weld a flat washer to the broken bolt,then weld a hex nut to the washer,a MIG works best for this..often the heat from welding loosens the bolt and it'll come out fairly easily..
 

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I'm definitely with tractor-holic on this one. I was able to drill one out well enough that, when I used the tap, it just cleaned out the original threads.
 

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Don't think the PB will do much good in the drilled hole. Some claim heating it up and melting wax into the threads before removal works. I have never tried it.
 

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Automatic transmission fluid and acetone in equal parts works better than most commercial penetrating oils and lots cheaper. Remember to use never seize on the new bolts!
 

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Discussion Starter #9
I've been hearing about ATF and acetone for years, but have never tried it. these things are rusty as can be and broken off flush with the surface, so I might give it a shot.
 

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If you drill, it is critical that you drill very carefully, and be certain the initial drill is centered in the broken off bolt. I think the block is likely aluminum, and those threads can be easily wrecked by a wandering drill.

Can you face the end of the bolt with a file or small grinder to make it as flat as possible, then use a punch to be sure your drill starts in the center? If you get a good starter hole, soak for a day or two with penetrating oil or home brew to increase the odds of it breaking loose if and when you try the easy out.

In all cases, don't be in a rush. Take your time and be very deliberate with the drill.

Good luck.
GB
 

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No love for EZ Outs. I would drill a 1/8 pilot hole. Then work up the diameters to 7/32. At that point, use a dental pick to clean remains of the bolt off the threads. Use a new 1/4 20 for a chasing tap. Takes awhile but I don't have a welder. I would buy a couple 1/8 bits and maybe 6 new bolts. Use lots of oil and go slow. :D
 

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I have never had much success with extractors either. I always start with a sharp punch to center the hole and then use a starter bit, they have 60 degree flutes and a stubby shank so they do not wander. If you notice you are off center after stepping up a few drill sizes, you can drill till you almost see the threads on one side and use a small round file or dremel tool to carefully grind out the other side of the bolt, then pick away at the threads. Also if you use a tap to clean out the threads, after using a regular tap, use a bottom tap ( easily made by cutting off starter / taper threads off with a grinder ) so you get full threads right to the bottom of the hole.
 

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Also if you use a tap to clean out the threads, after using a regular tap, use a bottom tap ( easily made by cutting off starter / taper threads off with a grinder ) so you get full threads right to the bottom of the hole.
I've never had to try it, but I've read that you can make a thread-chasing "tap" (just to clean up threads, not cut them from scratch). You start with a grade 8 bolt, then cut relief grooves lengthwise, with a grinder. The relief grooves provide room for stuff that the tap is scraping loose, so it doesn't just bind up the threads.
 

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I was in the same boat last week. To top things off I broke a small drill bit off when drilling the broken bolt out. Try drilling a hole with a broken bit in it....
 

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The very best way to do this is the method mentioned by TH above. Weld a nut to the broken off bolt and unscrew it. If you don't have welding capability, the next best is to get a good solid center punch right in the middle of the bolt and drill at the tap drill size. If you hit the center well, you'll drill out the middle of the bolt and only leave the helical threads sitting in the grooves, which can be picked out as also mentioned above. Then run a tap (use cutting oil!) through the hole to clean up.

Failing those two methods, use an EZ-Out as a last resort. If the bolt isn't frozen tight in the hole with rust they can be handy, but most are just not as strong as the actual bolt. The Ridgid ones are the best I've used as well. They are strong because they have a large cross section - as large as will fit - and they are solid. The helical ones don't have as much cross sectional area so they are weaker and will break easier.
 

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I was in the same boat last week. To top things off I broke a small drill bit off when drilling the broken bolt out. Try drilling a hole with a broken bit in it....
I've had some success by feeding a light gauge copper wire down through each flute of a broken drill bit and then twisting the two pieces of wire together like a twist tie to wind the drill bit out.

It works often enough that it's always my first attempt for broken drill bit removal.
 

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Discussion Starter #19
Don't think the PB will do much good in the drilled hole. Some claim heating it up and melting wax into the threads before removal works. I have never tried it.
If I can drill all the way through and hit open space underneath, I should be able to put that PB under the bolt, where, hopefully, the rust is less. The PB should then creep up the threads so it'll get into the rust from the top and bottom. I hope.
 

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Discussion Starter #20
I've had some success by feeding a light gauge copper wire down through each flute of a broken drill bit and then twisting the two pieces of wire together like a twist tie to wind the drill bit out.

It works often enough that it's always my first attempt for broken drill bit removal.
I'ne not heard of doing that before, but you can bet that the next time I break a drill bit off I'll give it a try.
 
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