Broken Bolt. Help!

ClassyJalopy

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I am in the middle of timing belt job and have managed to break off the lower alternator bolt.
Now I am not sure what's the best way to deal with this. Any suggestions are most welcome.
Also, anyone have the part number for the bolt itself?
20190313_102851.jpg
 

Mike6158

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If your shop (garage) is equipped with a drill press and a decent vise mounted to the press soak it with PB Blaster (or equal), preferably from the back side if the threads are exposed. Then you can center drill the bolt with a small (1/8") drill bit and then use a left hand rotation drill bit, size = whatever you would use for a screw extractor of the appropriate size, and hope that the left hand drill torque backs the broken bolt out. Failing that-If you're very careful and can find the exact center you could drill it out with the appropriate size tap drill (see chart from Bolt Depot below), and then re-tap the threads in the bracket. I'd guess 10mm but I can't know the thread pitch from a photo. Or, a machine shop can probably do the work for you.

How easy it is to fix depends in if you (or the previous mechanic) broke it because you (they) were turning the wrong way or it's really seized up. If it's "just" snapped off it'll probably back right out with vize grips clamped onto the remaining threads or, even better, if you can put a pair of nuts on the threads and then tighten them against each other, then use the inside nut to back the broken piece out.

PS -I always worry about doing this...

PSS - forgot to paste the table

Metric Tap and Drill Bit Size Table
TapMetric DrillUS Drill
10mm x 1.258.9mm11/32"
10mm x 1.09.1mm-
12mm x 1.7510.5mm-
12mm x 1.510.7mm27/64"
 

ClassyJalopy

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If your shop (garage) is equipped with a drill press and a decent vise mounted to the press soak it with PB Blaster (or equal), preferably from the back side if the threads are exposed. Then you can center drill the bolt with a small (1/8") drill bit and then use a left hand rotation drill bit, size = whatever you would use for a screw extractor of the appropriate size, and hope that the left hand drill torque backs the broken bolt out. Failing that-If you're very careful and can find the exact center you could drill it out with the appropriate size tap drill (see chart from Bolt Depot below), and then re-tap the threads in the bracket. I'd guess 10mm but I can't know the thread pitch from a photo. Or, a machine shop can probably do the work for you.

How easy it is to fix depends in if you (or the previous mechanic) broke it because you (they) were turning the wrong way or it's really seized up. If it's "just" snapped off it'll probably back right out with vize grips clamped onto the remaining threads or, even better, if you can put a pair of nuts on the threads and then tighten them against each other, then use the inside nut to back the broken piece out.
Thanks for the reply. I broke it off in my garage while removing the bolt. I have soaked it in PB blaster on both sides and have since then put locking pliers on it to move it without any luck. The locking pliers have successfully ruined the threads therefore making the two nut approach impossible :bang:
 

abuck99

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Youre lucky - you have thread to hold on to.

Apply heat gun to warm it, then PB blaster or similar on backside and front side- hit it with PB for 1/2 day. If you have a welder or buddy with a portable welder fuse a nut on there and back it- slightly tigten then loosen. Could try to tap thread and jb weld two nuts together on there, or Nuclear- option drilling with Cobalt bits 90 degree drill
 
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It's been a while since I've been in that area... (thankfully) -- Is there any way you could take the whole bracket out? I always prefer doing this sort of thing on the benchtop rather than on upside-down and sideways. I'm sure that would make a possible bolt extractor or the welding method easier.
 

ClassyJalopy

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It's been a while since I've been in that area... (thankfully) -- Is there any way you could take the whole bracket out? I always prefer doing this sort of thing on the benchtop rather than on upside-down and sideways. I'm sure that would make a possible bolt extractor or the welding method easier.
I don't know if it is just a bracket or part of the block. If I can pull it out that would be the easiest!
 
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heat it up. could be that someone at some point put some locktite on it. heat it up good and hot (the bolt, not the bracket) and try tightening then loosening slowly and with as little force as you can apply so you don't break it off again.
 
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I was in this exact situation a couple of weeks ago on a bolt on the heads during my DT header install, if you can repair the threads I had luck either 1) double nut method 2) cross threading/force threading (rough threads) a nut then reversing it.

Using a welder has some dangers FYI. I was told you could ground something and make an unintended weld somewhere else in the engine or ruin electronics.

Heat/PB Plaster and a lot of patience.

IMG_20190216_171719.jpg


IMG4867596435901133358.jpg
 
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abuck99

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Using a welder has some dangers FYI. I was told you could ground something and make an unintended weld somewhere else in the engine or ruin electronics.
That is a good warning. I first learned about this when I went to have my muffler welded in place. Disconnect the battery and properly ground the welder on the truck.
 

ClassyJalopy

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No better time to get one...or phone a friend who has one.

I've dealt with so many broken bolts on my rusty LX, and the "twist sockets" can work sometimes. The double nut method can work sometimes. The welder works ALWAYS...just my two cents. Take it for what it's worth.
Harbor freighyt has a mig welder for less than $100.
How worried should I be if I have no prior experience or knowledge of welding whatsoever?
 

suprarx7nut

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How worried should I be if I have no prior experience or knowledge of welding whatsoever?
How much time do you have to spend watching welding 101 videos on youtube? This day in age, you can learn anything your heart desires, likely for free. It just takes time.

If the welder isn't an option I think a propane torch (be careful) and locking pliers should do it. If it's still THAT stuck after applying a bunch of heat with a torch then you may need to resort to some careful dremel work. I think that bracket comes off, though, doesn't it? It'd be way easier to deal with that on a bench.
 
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How worried should I be if I have no prior experience or knowledge of welding whatsoever?
Just read the manual and setup the welder properly (flux core probably). You can buy some flatbar at Home Depot / lowes for cheap and weld on the ground if you don't have a table... if you want to practice
 

e9999

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I would think carefully before drilling that thing yourself. It's very easy to drill off center if you don't have the proper equipment. A machinist can do it right. But that will cost a bit. Yes, heat is probably the best solution. Btw, and maybe counterintuitively, I have found many times that with a stuck bolt, tightening it first will often release the stuck...
 
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