Crusty rusty bolts and nuts

[JPA Cate]

Sune,

Jim and I have also used Kroil with success, and I am unfamiliar with the substitutes you can make up yourself. Soaking them overnight with penetrating oil is a start. However, what we call a " 1/2" drive breaker bar", with a 6 point socket to fit the nut, will help. Put some tension on the nut, and while the tension is on, tap it hard with a hammer. Keep un-doing the nut, if you've got the space in there. You're trying to break the rust joins. Another thing to try is to heat the nut with a propane torch, take advantage of the metal swelling slightly to try to turn it. Jim's had a lot of success with that.

From your photo, I think you're going to win on this one. It really doesn't look too bad.

Ann

[redhead]

Kroil can be bought at any plumbing or refrigeration supply house in the states, I would guess that to be true elsewhere as well.

[sune]

I went and got a nut splitter (Danish is "møtrik knuser" = nut crusher)
Great tool that I never knew about before.

Made a 50/50 of aft oil and acetone that I had on the boat and soaked the nuts in that. There's no Kroil or PB Blaster in the stores here. There's probably some equivalent products but i don't know.

One nut came loose after splitting it with the nut splitter and I could unscrew with the wrench.


Two other nuts were too deformed for the nut splitter to get a hold, and only having a drill and a belt sander, I tried with the belt sander Makita 9031 with a 60 grid belt and it was pretty efficient, so I grinded them right down and could easily remove the bolts. I didn't expect using the sander for this job and other tools might be more appropriate, but what a great tool!


Fourth nut snapped.


Only two left for another day.

Learning a lot and having a wonderful time!


THANKS!

[Mike Banks]

I agree with Soton. Use a nut splitter or a Dremel tool and break free the nut. Replace them as you go with quality stainless nuts and bolts--not 316 but the good one with extra molybdenum--and put nail varnish or enamel paint on the threads before you tighten the new nuts (unless you want to take off the entire rigging and check everything).

[Lepke]

In a pinch, a mild acid like is used on galvanized sheet metal before soldering. The acid dissolves the rust, leaving more room in the threads. In the US available in hardware stores that sell metal rain gutters.

[mholubec]

Kroil
Nut splitter
Hacksaw or sawzall if you have one
Depending on bolt diameter blue knife (cutting torch)
Pretty much in that order

[Cheechako]

Try a 6 point socket and bar, you may be able to break them off. The 6 point wont slip like a 12 point socket... if you can even get one on there. If you can get air to the boat an air wrench like they use for lug nuts on cars works well too.

Oops... I see I'm late to the party.

[SailFastTri]

Originally Posted by boatsrus

Soak it with wd40 for a while and then try an impact wrench.

WD40 is NOT a good penetrating lube. In fact, if you apply it first it will prevent other penetrating lubes form working. I'm not sure what's available in Denmark, but you want some spray fluid made for the job.

That said, I agree with using a small cut-off wheel when all else isn't working.

[boatpoker]

I would take a very hard look at that chainplate. With the corrosion on that longest bolt it is hard to believe you will not have crevice corrosion in the chainplate.

[waterman46]

Originally Posted by Soton

I'm not sure if you could do this in this case but if it is an incompressible joint (steel / steel) we would tighten the nut and shear the bolt. This will work even with quite large bolts with a big spanner and bar. Trying to undo them could limit your options by rounding off the nuts.

Why wouid trying to loosen them with a wrench be any different than tightening them, in terms of rounding off the nuts? If you can apply enough torque to break the bolt without stripping the nut, it doesn't matter which way you are trying to turn them. Might as well go counterclockwise until either it loosens or something breaks, right?

[waterman46]

Originally Posted by SailFastTri

WD40 is NOT a good penetrating lube. In fact, if you apply it first it will prevent other penetrating lubes form working. I'm not sure what's available in Denmark, but you want some spray fluid made for the job.

That said, I agree with using a small cut-off wheel when all else isn't working.

That's strange, I thought WD40 actually was made for the job. Do you have a suggestion for something better?

[sune]

Originally Posted by boatpoker

I would take a very hard look at that chainplate. With the corrosion on that longest bolt it is hard to believe you will not have crevice corrosion in the chainplate.

I'll definitely do that. Take them out, inspect them, replace them if necessary and re-bed them.
And check the other chainplates on the boat while I'm at it.

Cheers

[Soton]

Originally Posted by waterman46

Why wouid trying to loosen them with a wrench be any different than tightening them, in terms of rounding off the nuts? If you can apply enough torque to break the bolt without stripping the nut, it doesn't matter which way you are trying to turn them. Might as well go counterclockwise until either it loosens or something breaks, right?

Just my experience

[SailFastTri]

Originally Posted by waterman46

That's strange, I thought WD40 actually was made for the job. Do you have a suggestion for something better?

PB Blaster penetrant PB B’laster Penetrant | The B'laster Corporation

It’s the best stuff I know about for this job. It has such low viscosity and lack of surface film, if you spray it into a styrofoam cup it will leak through the the microscopic pores of the plastic matrix. Spray it on, wait 24 hours. If you’ve already used WD40 or other lube that blocks the microscopic channels it could prevent Blaster from penetrating as well.

It should be a part of every tool kit, imho.

Edit: WD 40 was developed as a water displacement lube and lubricant coating. It has a much higher viscosity than a penetrating lube. It’s also a great solvent for removing adhesive residue.

Second edit: If you use this tuff, make sure you use chemical resistant gloves, as it will also penetrate skin.

[Soton]

Originally Posted by Soton

Just my experience

Sorry Waterman my answer war a bit glib.

The thread in the tightening direction generally is not corroded and therefore the nut will tighten. Tightening the nut will put the bolt in tension. The thread vee acts as a stress raiser and a shear plane will develop and the bolt will fail by shear due to the tensile load.

Trying to undo the nut places no tensile load on the bolt. The bolt in effect acts like a spring. You have not got the same stress raiser effect as you have in tension and you are relying on the bolt to fail by shear only.

So yes trying to undo the nut may result in snapping the bolt or the shear force required to snap the bolt may be more than the shear force required to round the nut.