E: Engine Blasting crankcases

greg brillus

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Like anything in restoration it is in the preparation that the final results will be either great or poor. It takes up huge amounts of time, but when done right , it ends well.
 

Simon Dinsdale

VOC Machine Registrar
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VOC Forum Moderator
As these crankcases are a bit worst than a bit of oil stain and have some serious surface corrosion in places (but not eaten into the metalwork), my plan is:

Remove every item to leave just the cases absolutely bare, inc cylinder studs, spindles, oil pump sleeve, oil way blanking screws etc.
Clean / degrease with engine degreaser & power washer.
Remove gasket sealant from bottom of each hole
Vapour blast the cases, heads etc at a local company.
Keep cleaning away glass bead residue with power washer, compressed air , small pipe cleaners for oilways and keep going until I'm 100% sure every last bead has been removed.
Then and only then, start the rebuild.

As for using spint stripper etc, have you tried using what is described as paint stripper in the UK now? All the active chemicals have been banned and removed so what is sold as paint stripper today should really be prosecuted under the trade description act.

Simon
 

greg brillus

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I seriously doubt they will simply vapor blast the cases without them being bead blasted first. The vapor blasting simply does not have the strength to remove difficult stains or similar whereas the bead blasting will. In any case I strongly suggest you remove the pump sleeve, you will find it extremely difficult to successfully mask off the timing side area enough to stop grit (either from beads or the vapor blasting medium) getting in behind the upper cavity beyond the pump sleeve. I'd hate for you to make an expensive mistake..........
 

Bill Thomas

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As long as it's clean inside after washing, Who is going to see the stain, Outside I would wire brush then wet and dry by hand.
I cleaned off some salt problems like this and was pleased.
We did a Bike that had been sand blasted some time ago, Not by us, And thought it was clean, But after pumping some oil around, We soon found it needed more !!, I would not sand blast again.
Cheers Bill.
 

Cyborg

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VOC Member
For stripper, you would probably have to see what's available for industrial use. Any aircraft maintenance bases around your area? They would know what is available. Who knows you might find someone sympathetic to your cause. If you can't find anything perhaps they can suggest something else. If I hadn't had such success with my Commando cases, I wouldn't be a promoter of chemical strippers and hate abrasive blasting so much. When I was done with the cases, they looked exactly like they did when they came out of the factory mold. The surface was perfectly clean and not altered in any way and they looked like they would pass for NOS. Perfect for restoration and no worries about abrasives hiding anywhere. I wish I could find that same stripper.
You could try cleaning a few pieces in a bath of oxalic acid and see if you like the results. It should still be available there in dry form and you can mix it to whatever strength you want. Plus it will come in handy for cleaning other things. Easier to dispose of afterwards.... diluted enough, its no worse than tossing out your rhubarb leaves. On this timing cover, it goes from.. as is, to B15 stripper, to oxalic acid bath. It will give slightly different results depending on the alloy, so something to keep in mind if doing a test.

26023
 

vibrac

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VOC Member
Oxalic acid? If I remember from my wine making days that's the acid in rubarb ....... Now there is an idea!
 

Cyborg

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VOC Member
Actually when I needed some to remove some iron particles from car paint... the supplier was only set up to sell large quantities. He said go get some rhubarb leaves and toss them in the blender. I tried it and had limited success. I think the wood working folk use oxalic acid as well. Better to get in powdered form and mix your own... I mostly use it as a rust remover before tossing whatever it is into the ultrasonic cleaner.
 

Nigel Spaxman

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VOC Member
I bead blasted mine. Someone had done it before anyway. The main thing is to clean really well to make sure no media is left inside. There aren't many holes anyway. Blow everything out with air. Remove all blanking plugs so there are no blind holes that could hold media. Then use soapy water and clean all passages with pipe cleaners. Use some brake clean as well. After it is dry check for media with more pipe cleaners, if there is any do it all again. I think people who had trouble must not have cleaned the media out. Even if you use soda blasting or dry ice blasting there can still be dirt in any of those holes. Probably the worst thing that could be inside your engine is alumimum oxide particles.
 

Gene Nehring

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VOC Member
I seriously doubt they will simply vapor blast the cases without them being bead blasted first. The vapor blasting simply does not have the strength to remove difficult stains or similar whereas the bead blasting will. In any case I strongly suggest you remove the pump sleeve, you will find it extremely difficult to successfully mask off the timing side area enough to stop grit (either from beads or the vapor blasting medium) getting in behind the upper cavity beyond the pump sleeve. I'd hate for you to make an expensive mistake..........

I would also be looking strongly for corrosion of the aluminum. As those cases look fairly well beaten up buy the elements. Having worked with aluminum on seaplanes and repairs of them its often that the separation / corrosion is not visible or slightly visible from the surface. As good clean as proposed would give an indication of damage if any.

Thoughts?
 

Mr. Boring

Well Known and Active Forum User
VOC Member
Here's an example of a nut rusted rocker cover from a BSA. I was cleaned in a industrial washer with an aluminum cleaning detergent that won't react to aluminum like some dishwasher detergents do. It was then soaked in a derusting solution like evaporust for 6 hours then rinsed. I doesn't have the issues of some acids making a raw fast rusting steel. It won't attack most paints if used for moderate times. Good for sympathetic reconditioning. If you look close you will notice the natural shine that the casting had between the corrosion.
 

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