Snapped crank pulley bolt... ideas?

[turabaka]

So I managed to snap off the crank pulley bolt flush with the crank. Nothing left of the head. Any ideas on getting it out of there?

[A18A]

did it happen by trying to loosen it or tightening it? It should be about finger tight if it happened when tightening it (if it threaded in easily).

If it happened trying to loosen it, maybe weld a bolt to it or something? or that thing you can get where you drill a hole into it and wind a left handed thing into it till it starts loosening

[2oodoor]

Couple of ways I'd try: left handed drill bit after heating up the remains and melting some wax in between the thread area, try backing ir out that way. Or weld a grade 8 bolt or nut to it.
If all else fails you can always put a tack on it with the pully on and run it like that
Those are fine threads so clean them out before a new bolt if you get it out.
When tugging on it to break it loose tug it both ways like it was a tap so your sure to keep it from stripping ok that kinda helps relax stretched threads so to speak.

[AccordEpicenter]

make a mark in the center of the remaining bolt with a center punch and drill it to use an extractor. if the extractor snaps off i would try welding a bolt onto the remaining bolt and try backing it out that way

[cygnus x-1]

I think I would try welding the bolt head back onto the bolt. Drill a shallow hole in what's left of the bolt in the crank. Then drill a matching hole through the broken off head of the bolt. Now you can hold the bolt head up to the bolt where it was originally and weld in the hole completely. Use an impact wrench to back the bolt out. Impact wrenches are far less likely to break bolts because they don't apply a constant torque. The vibration also helps to loosen things up.

C|

[turabaka]

I think I would try welding the bolt head back onto the bolt. Drill a shallow hole in what's left of the bolt in the crank. Then drill a matching hole through the broken off head of the bolt. Now you can hold the bolt head up to the bolt where it was originally and weld in the hole completely. Use an impact wrench to back the bolt out. Impact wrenches are far less likely to break bolts because they don't apply a constant torque. The vibration also helps to loosen things up.

C|

I think this is what I'm going to end up trying. Already tried a screw extractor and it just snapped off. Hopefully I can get it out of there this way.

[cygnus x-1]

Every time I've ever tried a screw extractor it has broken off. They're somewhat brittle so you might be able to chip it out (sort of) with a hammer and punch or air chisel. Or just leave it in there and weld over it.

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[turabaka]

Every time I've ever tried a screw extractor it has broken off. They're somewhat brittle so you might be able to chip it out (sort of) with a hammer and punch or air chisel. Or just leave it in there and weld over it.

C|

the screw extractor isn't stuck in there, I just snapped it in half. I have a nice hole drilled a decent way through the bolt, so tomorrow I'm going to try your suggestion of welding the hole up. It can't be in that tight since I was only using it to rotate the crank pulley to tension the timing belt.

[cygnus x-1]

the screw extractor isn't stuck in there, I just snapped it in half. I have a nice hole drilled a decent way through the bolt, so tomorrow I'm going to try your suggestion of welding the hole up. It can't be in that tight since I was only using it to rotate the crank pulley to tension the timing belt.


And it broke? That's bizarre. That bolt is pretty big; it must have been damaged already. Welding up the hole should make the bolt contract and loosen up too.

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[2oodoor]

Why would you drill a hole in the broke bolt head when you could just use a large nut? Just seems like it'd save time.
Ive broken every easy out Too and always more sucessful welding another head on using a nut or what fits the configuration. Probably dont want to heat it up too much unless you have a new crank seal though

[Rendon LX-i]

Weld a nut to it. AN it wont heat the cast or damage it. I have dont this once. Kinda like taking a exhaust stud out of a small block or any type of v8

[lostforawhile]

Why would you drill a hole in the broke bolt head when you could just use a large nut? Just seems like it'd save time.
Ive broken every easy out Too and always more sucessful welding another head on using a nut or what fits the configuration. Probably dont want to heat it up too much unless you have a new crank seal though

you drill a hole in the center to relive pressure on the threads, to do this right you really need to make a drill guide to put a center drill dead on center, if you get it right on, you can keep drilling the bolt threads out in progressively larger sizes until the remains of the bolt just shred out

[2oodoor]

I understand that and somewhat agree but I was responding to drilling a hole in the broken head which woulld be quite difficult and I wouldnt attempt it without a drill press. No big deal it just seems like extra steps.
I agree it would be a way to save the bolt possibly but I am assuming a new bolt will be put back .
All of the suggestions are good and should achieve desired results.

[lostforawhile]

I understand that and somewhat agree but I was responding to drilling a hole in the broken head which woulld be quite difficult and I wouldnt attempt it without a drill press. No big deal it just seems like extra steps.
I agree it would be a way to save the bolt possibly but I am assuming a new bolt will be put back .
All of the suggestions are good and should achieve desired results.

I thought he was trying to get the broken bolt out of the crankshaft snout? this is the safest way to do this. if you have a drill guide that fits over the crank snout, then the hole would be dead centered, you drill with a center drill first,then the regular drill bits will follow that hole

[ecogabriel]

you drill a hole in the center to relive pressure on the threads, to do this right you really need to make a drill guide to put a center drill dead on center, if you get it right on, you can keep drilling the bolt threads out in progressively larger sizes until the remains of the bolt just shred out

My dad did that several times with broken bolts and screws. It works, but you need a steady hand, and patience

[cygnus x-1]

I understand that and somewhat agree but I was responding to drilling a hole in the broken head which woulld be quite difficult and I wouldnt attempt it without a drill press. No big deal it just seems like extra steps.


Maybe some people like to do things the hard way. Did you ever think of that? Huh? Huh?

Ok, yeah. Welding on a nut would be easier. I suppose. But geez, how boring is that? Always doing things the easy way.

I'll stop now.

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[2oodoor]

:cool: Written explanations always are at risk of misinterpretaion.
Im used to having tubs of spare hardware laying around so having a sacrificial nut was assumed lol

Lost that was a brilliant idea for the pilot hole set up.

[lostforawhile]

:cool: Written explanations always are at risk of misinterpretaion.
Im used to having tubs of spare hardware laying around so having a sacrificial nut was assumed lol

Lost that was a brilliant idea for the pilot hole set up.
thats the same way I changed that threaded stud on the antenna base to a threaded hole

[Dr_Snooz]

I bought an Easy Out set with some left-hand drill bits. I've honestly never needed the Easy Outs as the bolt always comes out with the left-hand bit. I admit readily that I am not an expert in these matters and have never had to do a bolt the size of the crankshaft pulley bolt, however. Anyway, I just thought I'd throw that out there FWIW.

[lostforawhile]

I bought an Easy Out set with some left-hand drill bits. I've honestly never needed the Easy Outs as the bolt always comes out with the left-hand bit. I admit readily that I am not an expert in these matters and have never had to do a bolt the size of the crankshaft pulley bolt, however. Anyway, I just thought I'd throw that out there FWIW.

the issue with easy outs, if a bolt removal fails you can dismantle the part and have a machine shop remove it if needed, if you bust off an easy out, you might as well forget it, they are made of extremely hard material and very brittle, they are also almost impossible to remove. There are tap distigraters that some high end shops have, but it would cost so much, unless it's a crank on a Bugatti or something, you might as well buy a used engine. If it looks like an easy out will be needed let a good shop take a look at it first, I spent 4 hours once removing a broken off tap in something using a 30000 rpm pencil grinder, ate up 25 diamond bits, it came out, but if a shop had to do this,you will end up paying out the ass,snooze you are right on the left hand drill bits, you really need an accurate center hole first, then make the hole bigger and bigger then use a left hand bit