Seized stainless screw into aluminium

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Ex-SolentBoy

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The offending part is held on by 4 screws, 3 of which came out albeit reluctantly. Despite having only been in there a couple of years, they have the dreaded white oxide powder. No problem cleaning these up and refitting with Tefgel the way they should have been done in the first place.

The fourth is a problem. Applying the same force seems to turn it a little, but then I can feel the Allen key starting to rotate in the hole so I stopped.

Are there any special tricks to remove the offending screw? Unfortunately it is on the boat so I cannot take it to a bench to work on.

All sensible suggestions appreciated, and stupid ones as well, as long as they are funny :p
 
SolentBoy said:
The offending part is held on by 4 screws, 3 of which came out albeit reluctantly. Despite having only been in there a couple of years, they have the dreaded white oxide powder. No problem cleaning these up and refitting with Tefgel the way they should have been done in the first place.

The fourth is a problem. Applying the same force seems to turn it a little, but then I can feel the Allen key starting to rotate in the hole so I stopped.

Are there any special tricks to remove the offending screw? Unfortunately it is on the boat so I cannot take it to a bench to work on.

All sensible suggestions appreciated, and stupid ones as well, as long as they are funny :p
Click to expand...


if all else fails drill them out.
cold n slow with a sharp hss drill bit, drill a small pilot hole first
 
Not sure if the same brands are available outside the US but there a couple of really good penetrating oils to try. Many swear by a brand called Kroil. Think it originally came from the aviation industry. Another is PB Blaster.

Forget WD40 and similar. Do very little to break loose a seized fastener.

In your situation time and patience are your friend. Soak the offending fastener in your goo of choice and let it sit a day. If you have time, soak it again and let it sit another day.

Then tap the head of the fastener with a small hammer or something. Don't whack it hard, just firm taps, repeated for a couple of minutes. Try it again. If still stuck try heat next. A hand held butane or propane torch (no not a flashlight but a thing that shoots flames out the end, whatever they are called "over there"). Try to use a fine tip and heat the head of the fastener pretty hot but be very careful not to heat the aluminum part too much. Very careful as getting hot will destroy the temper and strength of the Al.

Then try again. If the Hex socket is reamed out you can get a devise that looks like a socket but has a tapered, reverse threaded hole in the socket. Fits over the head of the fastener and the harder you turn the tighter it grabs. I do not recommend EZ Outs, which look like a tapered, reverse thread drill bit that would insert in the hex hole. They are very brittle and frequently (usually) break off in the fastener leaving you with a bigger problem than before.
 
If you are sure the seal is broken, allowing slight movement you could try a suitable sized torx bit in the allen head. You may have to hammer it home, but better losing a torx bit and getting the screw out whole than having to drill it.
Of course, if the seal is not broken use a suitable penetrating fluid (not WD40) and hold a hot soldering iron on the screw head for a while.
Last resort... left handed drill bits and/or easy-outs.
 
If you have an LPG gas pencil type soldering iron ( the ones for about £15-20 ) stick the soldering bit into the allen screw hole and leave it there for as long as you can hold onto it till your arm hurts. At this point the different materials rate of expansion normally allow relatively easu removal, Failing that Aldi are doing easy out screw removers for about a fiver.
Good luck !
 
I was also going to suggest heat - but others have got there first. Rather than applying a soldering iron of some kind to the screw directly, I would probably insert the Allen key and heat it with a small gas torch - for example the LPG gas powered soldering iron with the burner head fitted rather than the soldering tip. This will distribute the het through the screw more uniformly - and you can attempt to undo it at the same time (use pliers!)

You may soften the Allen key if you overdo it, but they are cheap.

If that does not work, you could try cold instead - get a freezer spray (such as a wart remover) and cool the screw via the Allen key.
 
Heat ... where possible.
The aluminium expands more than the stainless steel but with a small screw the difference is so small in absolute terms that its often not effective although works well with large items.

Trouble with release oils such as PB blaster or Plus gas is that they just dont penetrate the joint.

Gentle persistence combined with heat and release oil, esp if you can get it to move a little, is probably the way forward.
A few taps with a hammer straight onto the head may help.
 
I'd be looking at heat as mentioned and then an impact driver with suitable allen bit of course. Plusgas is a good penetrating fluid and you can also get it with graphite in it. It can take ages to penetrate though, the longest I've seen was a screw on my dads boat we spent two weeks removing. It got a squirt and a good thump from the impact driver every day until it was ready to behave itself. That was also S/S in Aluminium.

Just as an aside, ACF50 mentioned above is amazing stuff. It's not cheap but it's worth every penny, I've used it for years. I paid about £30 for 2 cans several years ago from ebay.
 
I would be reluctant to use one of those easy-out or reverse screw type stud removers in the hole.. if they snap in the hole you would be really stuck.

FWIW I recently removed my compass from the pedestal to check on the steering grease - Four small stainless bolts into a thin aluminium Whitlock casting. All four were stuck and snapped off (even after using a proper penetrating fluid beforehand).

It was possible to drill out the stainless but you have to be so careful to stay central... one I retapped and the others I helicoiled so that in future I have stainless against stainless.. If you're near Portsmouth and want to borrow the Helicoil tool then PM me.. The inserts cost pennies - it was the tool/tap kit that cost pounds!
 
My fitter mate showed me what to do when I wanted to remove 4 m8 stainless bolts stuck in some ally on a 30 year old outboard , he gently warmed them up with a blow torch the squirted wd on them , the heat and capillary draws the wd into the thread , clamp the mole grips on and just start move gently backwards and forwards and they will come out , all 4 of mine did , with no damage to the thread in the aluminium :D
 
Ammonia - or whatever it's called in liquid form - is alleged to break down the Alu Ox.

Easyouts are great, but once you have broken one you are in a whole world of trouble.

I'd leave it soaking in Ammonia, then hit it with a hammer and drift to make sure the chemical bond is broken, finally using the Allen key again.
 
Phoenix of Hamble said:
if its a metric allen key, then use the slightly larger imperial one (or vice versa) and tap it in with a hammer... its too large to 'round off' the head, and often does the trick... worth a go before trying to drill it out anyway.
Click to expand...

Or an appropriately-sized torx - bashed in with a hammer.

Removal of the tool from the fastener is LAAEFTR, once "back at the bench".

My "engineering" today involved getting medieval on a rusted, snapped off epoxy'ed-in countersunk machine screw on the tiller for the autohelm bracket.
After grinding away the epoxy on top to clear the head (Dremel), but failing to get purchase with a large flat-blade screwdriver (or impact driver, tried tapping with a punch), there wasn't enough to get a stud driver on the underside stump.
Fileing the stump flat, centre-punch and drilling (from the underside, so effectively left-handed) didn't work, so I had to carefully grind off the countersunk head (little cone grinder on Dremel), then tap it out.

I sanded it, and gave it a couple of coats of varnish; tomorrow, I'll stick in a new stainless allen bolt, then epoxy, varnish, etc, etc.
 
Last edited:
An update on this please

Ex-SolentBoy said:
The offending part is held on by 4 screws, 3 of which came out albeit reluctantly. Despite having only been in there a couple of years, they have the dreaded white oxide powder. No problem cleaning these up and refitting with Tefgel the way they should have been done in the first place.

The fourth is a problem. Applying the same force seems to turn it a little, but then I can feel the Allen key starting to rotate in the hole so I stopped.

Are there any special tricks to remove the offending screw? Unfortunately it is on the boat so I cannot take it to a bench to work on.

All sensible suggestions appreciated, and stupid ones as well, as long as they are funny :p
Click to expand...

I have exactly the same problem -- heat has moved things before but the size and location means probable damage to the pristine paint work -- have you been successful?
 
Where is it ?

I copy below a reply to a post on steering problems where I actually sheared the offending bolt. However this did give me access to the inside of the alloy casting so I could cut a slot where it would never be seen. It avoided using heat on the pedestal which would have blistered off the coating.

Our Whitlock cobra steering was well overdue a grease-up. Access to the pinion and top quadrant is by removing the binnacle compass and cover plate. Whoops! one of the M5 bolts sheared rather than come out of the alloy casting of the pedestal.
Scratched head and retreated to bar.
Used cheapskate Dremel substitute mini cutting wheel to slot the inside of the casting allowing good application of WD40 to the bolt. Luckily with grips on the two threads that remained above the casting it now undid.
IMPORTANT LESSON when reassembling use an anti-seize compound or at least grease to prevent future problem. I only hope that this does assist in the marine environment.
 
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