Twisted off bolt head -- now what?

ward cleaver

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This is the extension piece for a 1970 33hp Evinrude. I was lucky that the broken off bolt head did not prevent me from taking off the extension. Now that I have it accessible for further surgery to remove the remaining piece of the bolt, I am concerned that if I just grab a hold of it with my vice grips, it may just break off again. I'm sure this situation has come up before. What is the recommendation? The paint job is decent on this motor, so I don't want to ruin it by burning off the paint with a flame. So I assume plenty of WD-40 is the best course of action? BTW all the other bolts came off fairly easily.

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1946Zephyr

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Re: Twisted off bolt head -- now what?

I would get an oxy/celylene torch and concentrate the heat on the bolt only. Use a small fusing tip, so it doesn't hit the aluminum. Get that baby glowing hot, then let it cool down. Once it's cool, you should be able to get a vice grip on the stud and remove it. You'll be able to tell, whether it's going to come out or twist off. If it feels like it isn't going to come out, then repeat the heat up process.
 

tpenfield

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Re: Twisted off bolt head -- now what?

I remember those 33 hp Evinrudes. Popular engine back in the day.

If that where mine to fix (i.e. extract the remains of the bolt), I would . . .

- Soak some PB Blaster or Liquid Wrench into it for a day or so.
- Heat the surrounding material with a propane torch while I tried to back the bolt out with Vice Grips.

You may want to try a couple of heating/cooling cycles on the surrounding material before you go with the vice grips.
 

boobie

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Re: Twisted off bolt head -- now what?

By heating the bolt you're only expanding it. Heat the area around it. Mix up a 50/50 solution of acetone and atf and try that on it also. Get Mapp gas rather than propane as it gets hotter.
 

ward cleaver

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Re: Twisted off bolt head -- now what?

I have propane but no oxy. I'd really prefer not to heat it anyway. I guess I'll just keep spraying on penetrating oil each day until it's time to put it back together (which could easily stretch into many days or even weeks at my pace). Then give it a turn and see what happens.
 

ward cleaver

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Re: Twisted off bolt head -- now what?

Just thought of a great idea: cut a slot with my dremmel in the top of the bolt head and then hit it with my impact driver. I'll give it at least a few days of WD-40 first though.
 

JDusza

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Re: Twisted off bolt head -- now what?

Concur with PB Blaster and DO NOT HEAT the bolt. Heating the bolt, as explained, will expand it and make it tighter. You want to expand the hole around the bolt.
Slotting is a great idea. Been successful in the past.
Worst case, you may need a carbide drill and an EZ-out.
J
 

boobie

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Re: Twisted off bolt head -- now what?

WD-40 is one of the most ineffective products you can use to break a stuck bolt loose. It has a lot of good uses but not for this job. But, it's your bolt.
 

laderwell

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Re: Twisted off bolt head -- now what?

get a stud extractor first, after pb blast soak. Also as last resort use a left hand drill bit, you have a good stem on the stud for a extractor to grab. 5.99 at Harbor Freight or better ones around
 

sschefer

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Re: Twisted off bolt head -- now what?

I've done my share of this and many of the recommendations are good ones, some are not. That's cast aluminum, heat the casting not the bolt.. Good idea=yes. Smack it with your impact driver, Good idea=no.. You'll probably just crack the casting. Use map gas or O/A Good idea=yes. Use PB Blaster Good idea=yes. Left hand drill bit. Good idea=no unless you own stock in the drill bit company it won't get enough bite to turn the bolt. That works on wood screws but not frozen corroded stainless steel bolts in aluminum. Use a bolt extrator or easy out. Good idea=no, if you break it off you can't drill it again.

My best luck has been with repeatedly soaking it down with PB blaster for two or three days then heating the casting to about 500 degrees and putting a pair of vice grips on the bolt and working it back and forth just a little at a time until it finally comes free. Go to your local welding supplier to get a heat crayon. Infrared thermometers don't work very well on aluminum. If you can't get vice grips on it then take it to welding shop and have them tack weld a nut on it.
 

boobie

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Re: Twisted off bolt head -- now what?

Agreed X 2. Especially about the bolt extractors.
 

samo_ott

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Re: Twisted off bolt head -- now what?

I heat the housing with propane whenever I have to remove head bolts and they're sticky and it works all the time. Also if one does break I use propane also... It almost always works.
 

1946Zephyr

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Re: Twisted off bolt head -- now what?

Reguardless of how good you soak it, it won't come out, unless you heat it up. When these bolts get siezed up in the threaded holes, they are in there for good. LOL Even with propane, I usually end up drilling them out. So far, the only heat that has prevented me from drilling them out, has been oxy/celylene, because it's the only thing that can get the bolt red hot enough.
 

jimbo_jwc

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Re: Twisted off bolt head -- now what?

Find a stainlless nut and thread on or drill out so it goes on stud and arc weld it on .Wait till it cools some while applying penatrating oil not red hot . Work back and forth .
 

tpenfield

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Re: Twisted off bolt head -- now what?

Hey, I have an idea . . .

How about soaking some PB Blaster and heating the surrounding material?
 

Cofe

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Re: Twisted off bolt head -- now what?

I would get an oxy/celylene torch and concentrate the heat on the bolt only. Use a small fusing tip, so it doesn't hit the aluminum. Get that baby glowing hot, then let it cool down. Once it's cool, you should be able to get a vice grip on the stud and remove it. You'll be able to tell, whether it's going to come out or twist off. If it feels like it isn't going to come out, then repeat the heat up process.

I agree^^^^^^
Heating just the bolt red hot, will expand just the bolt and help burn corrosion off the bolt threads. I then like to spray PB blaster on the bolt to cool it, and the heated bolt will wick some PB blaster into the threads. "It will smoke like crazy"..... Let it cool "shrink" then use vice grips to remove the bolt.
Welding a nut on the broken stud also works well also using the above method.

Lots and lots of experience has taught me this from years in the industrial trades.
 

ward cleaver

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Re: Twisted off bolt head -- now what?

Hit it with WD40 for a few days. Then got it out in only a couple of minutes with two applications of propane heat and a shot or two of WD40. I don't know how badly stuck this bolt was. The others came out with no problem. So I was thinking this one really wasn't that bad. I just didn't want to risk grabbing it with vise grips and twisting off the part I could easily grab hold of.

Thanks for all the suggestions.
 

1946Zephyr

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Re: Twisted off bolt head -- now what?

That's great! Sometimes we get that lucky. Sometimes not. Many times, I had to go as far as drilling these buggers out and pulling the threads of the bolt out in little pieces. Fortunately, I did this with very minimal damage to the threaded hole and was able to chase the threads and clean them out. I typically use a longer bolt when I do this and catch all the threads I can without bottoming the bolt out.
 
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