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Removing steel bolts from aluminium casting


davel

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OK not really a boat maintenance question but hopefully the engineers (or Austin 12 owners) amongst you will be able to advise us.

 

We are trying to take off the water pump and the bolts are seized. We have already sheared off one and would also welcome advice on how to extract the rest of it. The engine has been standing since 1958, as far as I am aware all of that time inside.

 

The water pump housing and the piece it is bolted onto are both aluminium and we are not sure if the housing is threaded for the bolts, even though there are nuts on the back which came off fairly easily.

 

Thanks in advance.

 

Dave

 

 

I'm not an engineer but you could perhaps make a 'bund' out of plasticine or Bluetack, surround the housing with it and fill with diluted phosphoric acid or aluminium wheel cleaner, or Plus Gas. Leave to soak for a few days.

 

Almost right in fact you need to use CONCENTRATED NITRIC ACID You don't need to make a dam with blue tac either. Just immerse the bolt in nitric and leave to soak. The nitric won't hurt the aluminium once it has formed an initial corrosion coat that will protect it from further attak from the nitric.

 

In fact you can even warm the niric on a electric hot plate to speed things up.

Below is a link to a 'how to' page I wrote for a car forum a while back

 

http://www.100nxc.net/Forum/index.php?show...7&hl=nitric

Edited the link doesn't work because the the tread has been moved to a pay per view section of the car club. :lol:

Edited by bag 'o' bones
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Progress - well done! At least you can now use a vice on it, or support it while you show it a variety of hammers.

 

Richard

 

Please keep us informed, won't you.

 

We (Ange and I) have had a couple of weeks looking after my parents place whilst they were on holiday, and then spending a few days with them now they are back.

 

Tomorrow we will back on the boat but will get our son to post progress pictures on Photobucket so we can give updates but they may be infrequent.

 

I have printed off this thread so Dad has everybody's helpful suggestions.

 

More proof that this Forum is such a good resource what ever you are doing.

 

Thanks folks for all your help.

 

Dave

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'Fraid not, sheared off flush.

 

 

 

The studs at the bottom of the picture are in a slot in the piece they come out of which is an adjuster for the cam chain which also drives the water pump. There is brass castellated nut in between the two studs, which we need to undo with a 'C' spanner and that will release the water pump.

 

It's a 1931 Burnham

 

Dad is going to try this if he can get his blowtorch working!

Hi Davel,

Lots of great advice and at risk of adding the same answer within all of us inspired. The sheared off bolt, might be worth just drilling a hole on circumference say 3mm or equiv. down thread (wouldnt hurt re-engagement too much)and bolt will help releasing agent get in. I use Rustoff by Wurth may not be easy to find, but Plusgas is good. Also using Easyouts reverse spiral tap like tool, using tap wrench into centre hole drilled in bolt (should be softer now). Will still need release agent and maybe a little heat to aluminium housing.

But not easy to isolate heated area. But got to try and good luck. cheers Alvin

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  • 1 year later...

Steelaway

 

You've probably long since solved your problem, but I thought I would still add to the thread if anyone else finds this page and has a similar problem.

 

I work with aluminium for a living for the last 23 years and have come across this kind of problem many times.

 

There are several ways of removing steel from aluminium as long as the steel part is on show.

 

Firstly and the best way, as has already been mentioned before, use an easyout.

Try and flatten the surface of the bolt, as trying to drill on a slanted surface is a big pain, and drill a pilot hole down the middle as big a diameter as you dare without destroying the threads. Beg, steal or borrow an "easyout" screw extractor, this little tool goes down the middle of the pilot hole you have just drilled, and with a helix that runs in the opposite direction to the screw, will automatically bite into the side walls of the pilot hole as you turn to unscrew.

 

Diesel always works as a very good substitute to WD40 as a penetration oil for lubricating seized or rusted in bolts, leave submerged overnight (or longer if possible) to give it every chance to work it's way in.

 

Some years ago we had assistance from a university to help remove mild steel laminations from an aluminium cast rotor core and they used an acid to burn the steel away. It worked perfectly and left us with a skeleton of aluminium that was unscathed by the acid. The stronger the acid the quicker the process but the more restrictions apply when buying it.

 

At the polar opposite, if you wish to remove aluminium from from steel, we use a very strong alkaline called sodium hydroxide which is a controlled substance in the UK, we then accelerate the process by boiling the solution. Bearing in mind that it is usually rather thick sections of aluminium that we need to remove (5mm and above), you may not need such a strong alkaline for thinner sections, it just depends how long you are willing to wait for the process to complete.

 

If that fails you could try welding another smaller steel bar to it and use this as leverage to try and unscrew them, but I'd only do this as a last resort.

 

Greg, Hallam Aluminium Castings Ltd

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