How to free SS bolt from corroded aluminum fitting

[Cisco 37c]

Read SLIGHTLY heat. Aluminum heats and expands faster than steel and that’s what you want. Using a propane or map torch, apply only enough heat to make the Kroil sizzle then let it cool. Reapply as necessary. I rebuilt the entire rig using this technique without drilling even once.
This is the recommended technique from professionals and with patience, there is no drilling. But, use your own judgment. For me, I HATE to drill my precious aluminum for no reason.

[Ratty1978]

Originally Posted by coopec43

I am trying to free a stainless steel bolt from the aluminum mast step. I've spent about a week giving the bolt a squirt of WD40 each day but it hasn't made any difference.

Is there a time honored way to do it?

I came across a forum where it was suggested a 50:50 mixture of acetone and ATF (Auto Transmission Fluid?) would free up the bolt. It just so happens I have acetone and ATF fluid so I'm giving it a try. Ill keep squirting it daily for about a week and see what happens.

How to free a steel to Aluminum corrosion bond

Any other suggestions apart from heat?

Set up a jig to keep a drill bit on center. Get cobalt drill bit (not coated, solid). Maybe use a Dremel or die grinder to get the broken part flat. Try drilling carefully, only in the stainless, the jig protecting the aluminum. I've found that the heat from the friction and vibration from the drilling might be enough to get the bolt loose. If not, you're drilling a hole for a EEZE Out. Left hand drill bit ideal, it tends to unscrew the bolt, but I haven't seen them in cobalt.

[Arion]

As it is well known stainless steel is more electropositive than aluminium. Because of moisture at the contact between these two metals a current circulates and creats this electrolytic corrosion of aluminium. By this process aluminium is oxydized and makes this white powder (Alumina Al2O3 chemical formula)clamping the stainless steel inside its aluminium thread.
This powder looks not so strong, so why it clamps so strongly a bolt?
In fact to understand the reason it is necessary to know that Al2O3 is hygroscopic, it traps water and doing so increases very strongly in volume. Such a thin powder in this case is able to actively clamp every thing.
But understanding this process explain why the worst thing to do on a clamped nut is to put WD40 and any kind of liquid as this way, assuming that this liquid diffuses at the jonction, alumina powder increases in volume again and clamp more efficiently the bolt.
So the method, and it dose not works always, is to dry the bolt. I use a hot air blower set at 250°C. It is put 30 minutes above the bolt. It blows also the aluminium surounding to increase the play by thermal dilation of the surounding. If it does not works the only remaining solution is, as explained is the other threads, to break the bolt (not two difficult with SS) or/and drill it.
Aluminium is a perfect material durable and strong but very technical. There is a certain number of goofs to avoid. SS bolts must be mounted with these special anti corrosion coumpounds. And on my boat I continuously check exposed bolts, put a new layer of coumpound about every two years.
Good luck,
François

[skenn_ie]

The chances are that you won't. Get a Cobalt drill bit and some cutting compound and drill the thing. DO your best to get the drill centred, and be very careful not to bend the bit ... Cobalt doesn't bend, It breaks. The alternative is to drill the rivets and remove the plug from the bottom of the mast.
Some years ago, my brother, a commercial fisherman, cut an aluminium bracket off a steel mast because the stainless pinch bolt had fused. he then cut through the stainless/ally interface, and polished the surface. He couldn't see where one metal ended and the other started, they were seriously fused.

[Cheechako]

Originally Posted by skenn_ie

The chances are that you won't. Get a Cobalt drill bit and some cutting compound and drill the thing. DO your best to get the drill centred, and be very careful not to bend the bit ... Cobalt doesn't bend, It breaks. The alternative is to drill the rivets and remove the plug from the bottom of the mast.
Some years ago, my brother, a commercial fisherman, cut an aluminium bracket off a steel mast because the stainless pinch bolt had fused. he then cut through the stainless/ally interface, and polished the surface. He couldn't see where one metal ended and the other started, they were seriously fused.

Again...This ^^^^ But better yet, if the picture I saw earlier is the mast step, with those small bolts sticking up... you need to cut them off or simply drill from the bottom. YOU MUST BE ON DEAD CENTER WITH THE DRILL. A center drill would be great if you know what that is.... to get it started. A center drill has a big shank that doesn't bend. Then a small drill bit, then a big one , bolt size or slightly under, to follow the hole the small drill got you..
But if you just take this to a machine shop they can do that AND put in helicoils!

[abnt1]

Hi as an auto mechanic for several years I have faced the same situation.
My method was to heat the bolt as hot and as quickly as I could this expands both the bolt and the bore hole it is in then using a good quality penetrating oil cool the bolt head quickly while trying to keep the aluminum hot due to expansion rates the aluminum will expand more than the steel bolt. This should break the bond between, them then flood the area with penetrating oil and try to move it. You didn't say the size of the bolt head so It's hard to say if this method is practical ( smaller is harder to do) try not to put too much direct flame on the aluminum if using a torch It will damage the aluminum.. If you have access to a good heat gun you could use that in conjunction with a torch to keep the aluminum hot while cooling the bolt. Steinel makes a very good one ( pricey though ) You can rent them from a tool rental place...
Good luck

[jacktheflyer]

Originally Posted by Boatyarddog

is the step still attached to the deck?
Is it off, but has a stuck bolt stud in it?
The process will vary with other possiabilities.
If the step is off, cut the shank(threaded end) off flush with a die grinder, or grind flush with the base.
Use a punch to dimple the cut end in the middle, the penetrant works even better if you shock the bolt repeatedly, hammer and punch, every day for a week or so, even less.
The vibration will allow the penetrant to creep down the threads, and dissolve the corrosion.
Then try to turn it, a little at a time back and forth if it's moving at all you'll eventually loosen it.
If that doesn't work, you'll have to drill it out, this can be tricky.
Using a small sharp drill bits , titanium bits, progressively drill a bigger hole down the shaft center.
Once you get to the size of the bolt, the side will come away from the hole, and you should be able to pound out the carcass.
It's always a difficult job and one that can be frustrating.
Have any pictures of what your working on so we can see better?
SHOCKING THE BOLT WORKS WELL.
Cheers,
SV Cloud Duster

Agree with this. In my days working on motorbikes this was the only thing that worked.

[coopec43]

The thread is very long so just for the record at this stage.

• The aluminum fitting is off the yacht
• I am soaking the fitting in white vinegar at this stage. If that doesn't work I'll try acetone/ATF
• Time is my ally. While I am fitting out the aft cabin I can be soaking the fitting (for weeks if necessary)
• I have a butane bottle torch and a bench (pedestal) drill and LH drill which I will use if I have to

Just a thought: maybe I could drill and tap a hole on the other side of the fitting and reverse the pin (which I assume has been machined to take the bolt locator.) Of course the old bolt would have to be drilled out completely.

[Greg Mason]

Here is where the outboard mechanics have it over the rest of us. They have stuff exactly for this purpose which is not available to the general public. That may be a place to start. I have used Deep Creep and other products to release a frozen stuffing box, but there are very few options that actually work.

[coopec43]

Greg

That is another lead worth following I'm sure. Here's one hat looks interesting but I've just started. But I don't think an O/b mechanic would tell me their secret (understandably)


Thanks


I'll look at this thread too. One suggestion was brake fluid/diesel: I know diesel is very penetrating.

https://forums.ybw.com/index.php?thr...minium.366823/

[whmiles]

I had exactly this problem extracting many S/S bolts and screws from my aluminium steering pedestal. The answer is definitely heat. I used a propane torch (or butane). That and occasionally the use of an impact driver got them all out. Does take some time if you have several, but it does work.

[Buzzman]

Originally Posted by oOoOoOo

... A trick that really helps that no one mentioned yet is to put the piece in water directly after heating. This will definitely shock it loose.

I had a S/S rod passed through a tight-fit tube in an outboard leg (gear actuator) that was corroded solid and would not budge using WD40 or whatever.

I heated it over a propane stove, then plunged into cold water, and repeated half dozen times. Next tap with the mallet and it freed right up.

In a mast base, I'd suggest using a propane torch to concentrate the heat, and quench with floods of cold water from a bucket dipped overside.

According to what I read somewhere that gave me the idea, the dissimilar metals heat and cool at different rates, so they contract differently, and it is this differential expansion/contraction that 'cracks' the oxidisation in between, allowing the S/S to move/turn.

YMMV.

[whmiles]

Even better: heat AND cold.

[coopec43]

Originally Posted by whmiles

I had exactly this problem extracting many S/S bolts and screws from my aluminium steering pedestal. The answer is definitely heat. I used a propane torch (or butane). That and occasionally the use of an impact driver got them all out. Does take some time if you have several, but it does work.

Yes, I had the same problem getting bolts out my steering pedestal too. I got three out and busted the fourth. I tried to drill out the fourth and made a slight mess of it but I was able to thread the hole deeper and use a longer bolt.

Now you are suggesting heat? In my case would l heat the aluminum or bolt.

[whmiles]

You need to heat them both, but it is really the oxidised material between them that you need to get at. The only way is to heat both materials. But, I agree, heat AND cold is the way to go for sure, plus diligent use of discretionary force/impact. And patience.