Corrosion Stainless vs Aluminum

[alaskaflyfish]

If helplessly frozen into place and battery heat and impact does not dislodge the fastener try drilling a #40 or #30 hole thru the mast directly above the fastener and hose the inside of the threads with penetrating lubricant using a spray nozzle pointed downward. When complete, fill the hole with an aluminum pop rivet. This method increases the lubricating effect and decreases the time of penetration. Although and ugly small hole remains, it beats having a reamed out bolt hole with an ez-out cracked off in it.

[toodleoo]

Originally Posted by Kenomac

Won't the heat gun cause the paint to lift off the mast? Maybe if I understood the heat concept. How and what determines if I heat the bolt or the mast? By heating the mast, does this draw in the penetrating oil, or am I trying to expand the hole size by heating the aluminum?

The object is to heat the aluminum which will expand faster than the stainless steel bolts. In any case use a hand impact driver sparingly. Once a turn or 2 loosened you should be able to get some penetrating oil on the threads from the top of the fitting/mast interface.

[a64pilot]

Originally Posted by magellanyachts

What ratio ATF & Acetone please?

50/50

[UNCIVILIZED]

I know I've said it before, but... tighten, then loosen, then tighten, repeat.

Things may not move at first, but with some luck...

[JPA Cate]

And when you've finally got them out, since people haven't used anti-seize mounting things on your mast and boom, you will want to struggle every other screw out, and use anti-seize ALWAYS, when putting s/s into aluminum.

We always used to use the silver anti-seize that tries to spread itself everywhere if you're not careful, but riggers down here are using anhydrous lanolin, which is very cheap, and it seems to work well, too.

If that Antal fitting is marelon, be careful about using heat, but the idea of having a welder weld a nut onto the allen screw could work great without damaging anything, then use an impact driver, with fierce blows to it. You have to physically break up the aluminum oxide, which has expanded into the threads of the screw. Then the penetrating oil can really get in there. Your holes may or may not be reusable. Evans' idea is brilliant; and we have just drilled up one size, and introduced the anti-seize, with good results.

The penetrating oil takes a long time, and will be hard to introduce effectively on that vertical surface.

Ann

[Djarraluda]

Originally Posted by Foredeck

Just had this problem. Soak it in white vinegar for a couple of days. Really.

Just as I was thinking that nobody had mentioned this one !

OK, the other issue in my mind is that the "heat" methods work by causing expansion - essentially it can be any old expansion, then wait for it to cool down. That movement may break the corrosion, impact will assist in this because of the movement generated between the surfaces.
Improve the movement by heating just one surface, not the other. Also heat and sudden cool of one material will do the same thing.

So the methods and tools you use will vary depending on the materials and their finish. Choose whatever is appropriate to them and create that differential movement between the surfaces.

If using an open flame, I would be cautious of any recent application of any penetrating fluid. Clean-off the surplus and let it evaporate before bringing a flame too close. Trust me, it can get interesting!

Roger

[s/v Jedi]

I am not very patient with unwilling fasteners. My recipe is having a large collection of them aboard so that I can replace and some left-handed drill bits to drill them out and start turning the fastener the right way

The times that I managed to remove a stuck bolt from the mast with PB Blaster etc. the threads were still damaged more than with the drill bit method.

[senzafine]

recently i had to remove a 1/4 inch stainless bolt holding a damaged part
on an aluminum lower unit.the bolt pointed upward toward the powerhead
and wouldn't move.if it broke off drilling it out would be difficult as the
propeller shaft is in the way.

i sprayed it with pb blaster and applied force back and forth(also tapped on
it with hammer and mandrel).eventually it started to move but not far.had to keep doing this off and on for several days before it came out.

good luck

[Elie]

Galvanic corrosion action between stainless steel and aluminum essentially weld strongly the two metal, in a saline environment. No penetrant oil will do. Heat might some times but drilling the bolts or rivets is the only sure way to do this. It is important to use an antiseize compound when reinstalling any stainless bolt or rivet .

[boatpoker]

Originally Posted by Elie

Galvanic corrosion action between stainless steel and aluminum essentially weld strongly the two metal, in a saline environment. No penetrant oil will do. Heat might some times but drilling the bolts or rivets is the only sure way to do this. It is important to use an antiseize compound when reinstalling any stainless bolt or rivet .

A dielectric grease should always be used with dissimilar metals but I have many times free'd fasteners in this condition with penetrating oil, heat and impact.

[Kenomac]

I picked up an impact driver today which cost me €60, but the guy was the only one in town that had one. Gave the bolts a few good whacks, but still nothing.

Now the problem is I currently havine a working mechanism that I'm trying to improve, unlike two days ago when the hoist wasn't working properly. I don't want to push it one step too far and break off the bolts while trying to improve it. You know... "If it ain't broke, don't fix it." I'm getting very close to messing up a good thing.

So, I'll keep hitting it daily with some penetrating oil and giving it a good stike with the impact driver and try a little heat and just keep my fingers crossed that it'll free up. I don't want to push too far and break it.

[a64pilot]

That is it, just keep worrying the thing, often just one day it will come loose, eventually maybe.
Once you get them out, what is the plan? I use Tefgel I bought, a little tub of it, but in truth don't have enough time with it to recommend it, maybe in five more years I'll know.
Logic would dictate that a wrap or two of teflon tape on the threads of the fastener ought to work too?

You need to get it out if you can, at a convenient time, cause one day it won't be convenient and you will need it out, just now you can schedule when you want to tackle it.
If you end up drilling it out, likely you can install a threaded insert and keep the same size fastener, this can do two things, if the threaded insert is SS then it will seize in the mast but the bolt will be able to be easily removed in the future and of course since the fastener is the same size it won't look odd

[Bubu delaMancha]

Impact driver is the basic idea but i was afraid it simply would not provide enough torque and vibration. It's more like a watch repair tool.

That's why i said hammer gun. Basic principle is that it loads the bolts with constant amount of torque, while applying impact loading too. That makes it combined loading, which is what u are looking for. I had something like this in mind.

https://www.machinemart.co.uk/p/clarke-cat131-professional-heavy-duty-12-air/?da=1&TC=GS-000310131&gclid=CKSzkpCMi9QCFUI6Gwodpg4DjQ

[s/v Jedi]

A big impact driver like that will simply turn the bolt in two. I have a small battery operated Bosch impact driver which will be more than enough to bring fasteners up to 8mm to their breaking point.

If a show of force to deal with this right now is wished, then it is much better to just buy new fasteners of the right size, then drill the old ones out and put everything back with new fasteners.

I see many different products mentioned to prevent galvanic corrosion... many of those are not designed to deal with this, meaning that there are better options than those. TefGel is probably the best product but it does not prevent the fastener from loosening. For hardware bolted onto the mast or boom, I recommend using a "blue" rated thread locker. It isn't the best option for preventing galvanic corrosion, but it helps a lot plus it keeps the fastener tight

[Kenomac]

Regarding this particular mechanism, there really is no bad time to deal with it. If and when the rope breaks or disintegrates, I can feed a replacement through the device. I'll just keep tackling it slowly until my mechanic friend shows up in 9 days. Now the need isn't nearly as urgent as when I started the thread.

Now I own an impact driver.