Using heat to free siezed machine screws

tjbrace

tjbrace

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My deck organisers are siezed and so are the machine screw fasteners (10 mm ss countersunk with slotted head). The fasteners pass through the deck and screw into tapped aluminium plates I am told. I have read here that heating the screws may help free them, but how much heat - hairdryer, hot air gun, or gas blowlamp. Any advice welcome.
 
Had this problem on my 38s5! Try lots of hot water first - it cleans and heats, then work your way up though I wouldn't use a blow-lamp.

FWIW when I got mine off Beneteau had direct replacements available through Foxes cheaper than any other make - but that was at a better exchange rate !!
 
Thanks BATOO, I will follow your advice. I shall replace with Lewmar Synchro equivalents as they have ball or roller bearings and, I hope, will take lubrication better.
Ps. You very kindly showed me over your Bonne Affaire in SYH in 2004 when I was trying to sell my previous boat. I was most impressed and eventually bought one. Ours is the charter version though.
 
when ally and stainless corrode together, the powder formed occupies more space than the original metal if you get what I mean, so the joint gets ever tighter. add to that, the corrosion product is insoluble and abrasive so you cant dissolve it out and penetrating oil only works if the problem isnt bad. as you guess you need to heat the ally which expands more than the stainless and makes the joint looser. heating the screws but not the ally would make the joint tighter until the heat got transferred

poly resin will stand reasonable heat but your problem is how do you get at the ally without damaging the surrounding materials and the seals. for example if you use boiling water, will it creep into the joint between the ally and the balsa in the sandwich.

in your position I would go for drilling out the stainless fixings if I could.
 
To free seized screws you usually need a good deal of heat like a blowlamp or welding torch but that's not a good idea at all if they are through the deck. Try soaking in WD40 or similar. If that won't do it you are probably faced with drilling or grinding the heads off and removing the fitting that way. You may then be able to squirt more WD40 down the hole and remove what's left with a mole wrench. If this fails is it possible to move the new fitting slightly allowing you to drill and tap new holes and still cover the old ones?
 
Thanks Tigawave, The product isn't mentioned on their website so I have emailed them. These organisers are double stacked so any lubricant has a long way to travel to get to the tapped plates and they are not accessible from inside without cutting holes in the moulded deck head liner.
 
We found a wall paper stripper - with just the bare hose, so a sort of steam source was good for loosening up all that sort of crud. Also not so hot that it might damage or burn the bits - but still hot enough that you need to be careful. Then of course our old friend WD40
 
Drilling the heads off is the way to go if a bit of hot water doesn't free them. Try bit of hot air gun on the plate together with WD40 or whatever
 
I've just freed up two pieces of almost similar alloy and I tried ACF50 at nearly £13 a can- no good, Plus Gas at about £8 a can equally unsatisfactory- blow torch but too much of a heat sink to be successful- end result club hammer and drift. The good news is that this last option is no good for you.

However, when I had to replace my broken teak grabrails the s/s 12mm machine screws had 'welded' themselves in place after 25 years and I could not shift them at first.

I tried a large bladed screwdriver with a mole wrench on the shaft but this skidded off and damaged the slot. I tried penetrating oils as above, but not ACF50 which I hadn't heard of at the time. I also tried a wheelbrace with a large screwdriver socket head and this was better than the screwdriver/mole wrench combination but only once I had started the screw.

To get the screws started I had to use an impact screwdriver, although a slide hammer would have been as good.

Anyway I hope this lengthy tale offers you something to try as an alternative- good luck.

By the way if you choose to drill into the head of thscrew, do get a cobalt drill bit this is a much more efficient cutter than an ordinary tungsten or carbon steel bit
 
At the end of the day its a combination of them all, its like a terrier with a rat, keep working at it and eventually they come loose, but its hell getting there!
In this case i would be thinking of an impact screwy, seems strange he cant get underneath, is it a bene? Ive just done the clutches on mine, counter sunk slotted screws thru the clutch centre BUT nuts accessible underneath thru the neat wood panel, the dremel soon sorted the nut, funny but the heat generated from the dremel grinder loosened it enough to unscrew it!
Stu
 
Another suggestion which sometimes has worked for me - apply pipe freezing spray to the screw/bolt, especially useful where heat would cause damage to the surrounding material.
 
In my case- a double-skinned boat with no underside access- the deckgear screws into tapped plates embedded in the manufacture process
 
I am sure this is my case too. By removing recessed deck head lights which are in the vicinity of where the organisers are fitted I can see no sign of backing nuts. I don't think it will be worthwhile to cut the deckhead and make inspection plates. Strangely, other deck fittings have removable panels in the liner below them giving access to backing nuts and washers.
 
My thanks to you all for your suggestions.
I will try a wallpaper remover as that will deliver very hot water to the fixings and then a screwdriver and molewrench. If that does not work, i will drill off the screw heads, remove the fittings (destroying them if necessary). That should give better access to the screw/plate interface where i will apply penetrating oil. Hopefully the screws will then move with a molewrench. If they don't I will grind them off and offset the replacement fittings to avoid the old screws.
 
Re: Using heat to free seized machine screws

It has been said that Coca Cola is very effective at freeing stainless bolts seized into aluminium. Try making a dam of plasticine around the fitting, then fill up with Coke. Leave for a while as the phosphoric acid, which I assume is the active ingredient, cannot be all that concentrated, can it?

Another possibility is washing soda. In the 'good old days' the motorcycle magazines had a regular article on cleaning aluminium cylinder heads, invariably entitled 'Go boil your head!'. This method used washing soda, sodium carbonate, and brought cylinder heads up like new. I would try it pretty much boiling if you can. Plasticine will take the heat; I used to cast lead in it.

Ultimately, as has been said, drill the heads off the bolts and grip the shanks with a Mole wrench to turn them. Beware though, stainless steel bolts are quite soft and the last thing you want to do is shear them off.
 
Re: Using heat to free seized machine screws

I'd agree with trying impact. Shocking a stuck bolt or screw often does the trick where everything else fails.
 
Re: Using heat to free seized machine screws

The theory of using heat on seized aluminium is that you drive off some of the water of crystallisation in the aluminium hydroxide, causing it to reduce in volume sufficiently enough to let the screw turn.
I've tried a hot-air gun and LPG blowtorch, with only slight success with the former.

I suspect that your fibreglass filling in the sandwich will suffer if you use heat to any extent.

Most freeing fluids are useless, they can't get in to work.

Probably the most successful is an acid - the acetic acid in vinegar frequently helps, but you could use citric acid or, with the correct precautions, dilute nitric acid. All three of the salts produced are water soluble, so you apply, heat wash with water and then go through the cycle again.

Try again, with hot air gun, acid and an impact screwdrived and you'll have a 50% chance of getting them out. If not you'll have to resort to drilling them out. In this instance not quite unfeasible as you can fill the oversize hole with GRP reinforced polyester.
I'd doubt the machine screws are tapped into the plate - probably an SS nut with the plate acting as a backing plate. In pratice the problem is the same.
 
Re: Using heat to free seized machine screws

I've had success using a soldering iron for screws and bolts that are siezed. With a small tip on the iron, you can usually direct the heat very accurately to either the screw or the retaining material.

Good luck Paul
 
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