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BF 130 - how to extract this broken bolt?

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stan101

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This bolt is one of two that attaches the zinc on the bottom of the frame. This is a hex bolt (6x40) with the head broken off and only about 1/4" protruding out of the bolt hole. Any suggestions on how to tackle this problem will be greatly appreciated. Thanks.
Stan
 

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If you have a propane torch, heat the bolt, trying to aim the heat away from the aluminum frame. You want to get the very end of the bolt hot and let the heat "flow" upwards. You don't need to get it cherry red or anything, just good and hot. Then, let it SLOWLY cool. After it is COMPLETELY cooled off, use a pair of VICE-GRIP pliers and grab the protruding bolt AS HARD AS YOU CAN get a "squeeze" lock on it and try and turn it out. DO NOT FORCE IT! If it doesn't come out with moderate force, try heating the bolt again but this time spray it with PB-BLASTER while it is still hot. Then try the VICE-GRIPS again. It should come.

The SECRET here is to not break the bolt off flush in the hole. You are very fortunate that you have the thing protruding from the hole to get the VICE-GRIPS on. DO NOT lose that advantage by forcing it and breaking it off flush. Fishermen do well at stuff like this because they have patience.

Good luck and let us know how it goes.
 
Thanks jgmo.

Now I have confliciting information, in that the local Honda mechanic said to heat the surrounding area around the bolt, but never the bolt. He said they use an acetylene torch. So what about their advice? Maybe I should first try the vicegrips with PB Blaster and tap, tap, before any heat? Or if I can get two nuts to lock on the piece and use a wrench instead of the vice grips?
 
Aluminum expands with heat and at twice the rate of steel.-----0.000012" / inch / per degree F.---------The white stuff you see is aluminum oxide and oxygen has joined with the aluminum and by nature this " white rust " so to speak has jammed up the works.-----So heating the surrounding aluminum may expand it enuff to loosen the grip on the threads.----Patience is key here as heat travels very quickly from the area that you are heating.---------With the oxy torch you get a much hotter heat scource and the part around the bolt heats up quicker.
 
The idea behind heat is that the two metals expand and contract at different rates. If you heat the steel of the bolt, the heat will transfer to the aluminum with no danger of damaging the casting or the finish but effectively heating both objects. Therefore,....... I DISAGREE ENTIRELY with heating the cast aluminum.

The separation actually takes place as the two differing metals cool. This "heat n beat" technique is most effective if the parts are allowed to cool. I would use an oxy/acetylene torch to do this myself but most guys don't have those so I suggested propane. Either will work.

I do like both of your ideas and either of those are also likely to work.
 
You are going to use a torch on a part of your engine that is attached directly to a Plastic boat.

Find someone with a mig welder, get a hand full of nuts that will fit over the remains of the bolt and weld one on. Then loosen the bolt. The mig will apply the heat needed with out flames. Have a bunch of nuts handy as you will be twisting them off as the bolt comes out.
 
Thanks for all the quick replies and good advice. You guys are great! The job has started slowly due to other distractions in life (tis the season), but soaking with penetrating oil is under way until I can get to it. Jumping ahead to the day its done, I want to apply Tef Gel, or something, to the threads of the new bolt(s) in order to prevent "frozen bolts" in the future. However, the purpose of the zincs might be comprimised, ya' think?

Also, the bolt holes should be cleaned out before inserting new bolts? Thanks for your interest and input. Stan
 
Always use a tap to clean out the " aluminum oxide "-------Use a sealer to keep water out.------Electrical contact will still be there even with the sealer used, has no effect on zincs.
 
Thanks for all your help on this.
The end result is that one of two stuck bolts came out after lots of patient work: propane heat, PB Blaster, tap-taps, more penetrating fluid with ATF and acetone mixed 1:1, slowly turning taking "no more that it gives you", but one broke off flush with the frame anyway. So, now I don't believe there is any possibility to drill it out, because the boat is on a lift and I have to work on a float. Since the zinc is located on the bottom of the frame, that would mean working on a floating platform trying to drill it upside down! I have no tow vehicle or a catamaran trailer.

One possible solution is to replace the bar zinc that was originally attached with two bolts with a different type zinc attached to the one good hole. However, this solution might result in inadequate zinc protection; I don't know how much it actually takes to do the job. Any thoughts on this or other suggestions? Thanks, Stan
 
If you opt to drill out make extremely sure you are in the center and use LEFT handed twist drill bits! Plenty of cutting oil, don't let drill bit get too hot, don't drill too fast use high grade carbon drill bits. Another course of action is to use weld techniques but the small the bolt the harder it will be. Look at YouTube videos!!!!

I was able to get a broken bolt from lower unit using cheap harbor freight 90 amp welder, took 3 failed tries with bolt, finally welded washer on and vise grips. Worked it back n forth small increments with pb blaster finally got out.
 
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