E: Engine Blasting crankcases

Simon Dinsdale

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Usually I avoid blasting crankcases and cylinder heads due to the fear of leaving the odd particle or two of blasting media inside the engine. I have heard of horror stories of engines been destroyed in only a few miles and so I have always cleaned such items with solvents etc and never had a problem.
However I'm currently working on a early series B engine that has been stood in a shed for 50 years and is quite corroded etc and needs more than just a solvent clean. See photo attached of what I am starting with. This engine has being nicknamed "The hairy B".

Options are vaqua /vapour (wet) blasting which gives a nice sheen to the alloy which looks as cast and also appears to seal the casting pores, and I have seen crankcases blasted this way still look good even after heavy use years later. Disadvantage is every last bead needs getting rid off after and the worry is some could be left lurking in the corner of an oilway etc.
Another option is soda blasting which has the advantage of being water soluble so its easier to eliminate the media after blasting but I don't know what the finished result looks like and even if it will remove aluminium oxide corrosion. Could anybody who had had crankcases or cylinder heads soda blasted post photo here showing the end result and their experience. Is is a matt finish or a slight sheen to it like vapour blasting? Also what do they look like several years later, ie is the surface pores sealed like wet vapor blasting?
I have read the various posts on the forum already about soda blasting but cannot find comments as to the finished look.
Thanks
Simon
 

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timetraveller

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I soda blasted a friends heads and barrels a couple of years ago. The bike has not been on the road since and so not subjected to salt etc. but they still look ok in his garage.
 

vibrac

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Why not get something minor soda blasted? its a cheap enough process get a mag cowl done you could always vapour blast it afterwards if you need to,no hidden bits on that.
Then you could let us all know
NB my 52 Trophy had head and barrel vapor blasted been OK the last 4 years.
 

davidd

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Simon,

I am not sure that you would be happy with soda blasting. I do it, but it is not as thorough as bead blasting or vapor blasting (vapor blasting is usually bead and some fluid used as a slurry). Soda blasting will not change the surface extensively. This means if it is "stainded" the way old cases can get to be, they will not look totally clean.

Here is a before and after of the inside of a timing chest that is soda balsted:
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Here is a close up of the cam area after soda blasting:
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You can see that the case is substantially cleaner and that what is left, what I have called "staining" is still present, but the machined area is much cleaner and I would expect the more aggressive bead or vapor blasting to look like the machined area does, very clean and no staining.

I don't mind the inside of the timing chest looking this way, but the visible surfaces probably need to have more aggressive blasting.

If you examine your cases you could ask the question "is there any passage in this engine that I cannot clean thoroughly after bead blasting?" If the answer is "yes", then you should consider not doing it. If the answer is "no", that your disassembly is going to be extensive and that you will spend time examining and cleaning all the oil ways, I think I would opt for the more aggressive cleaning.

I did a combination on these cases and I spent time focusing on all the threads and oil passages after cleaning and before assembly. I felt that was good insurance and I hope it works out well.

David
 

Simon Dinsdale

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Thanks for the reply & photos David, thats exactly the info I was after.

I don't know anybody local with soda blasting equipment so its not easy to have a trial. I do have a Guyson blast cabinet & extractor in my garage which I use for removing rust & paint off non engine parts and could adapt it to use a pressurised soda blasting bottle setup rather than use it outside in the back garden, but these cases and the rest of the alloy parts on the engine are heavily corroded & stained etc and so it looks like soda is not up to it.

There is a company 20 miles from me who do vapor blasting of crankcases etc while you wait so I think thats the route, along with every blanking plug out the cases and a very througher clean up after with pipe cleaners / compressed air, taps down threads etc.

Simon
 
G

Graham Smith

Guest
I had the mag cover from my Meteor vapour blasted.

The results were amazing.

I've tried looking for some photos, but can't find any.

I'll see if Josh has one.
 

Mr. Boring

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A regular glass beading will give you nearly the same look as the vapor blasting if you use virgin glass. The beads peen the surface instead of cutting into it. Blast first with older glass to clean and remove corrosion. Then follow up with new glass. It'll shine and the hardened texture with stay nice years to come. Remove everything bolted to the castings. Plug all holes very well before blasting and clean before before during and after. Soda blasting won't clean up corrosion.
 

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Mr. Boring

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Remove all dirt and oil before you blast! It won't stick on as easily if there's nothing to adhere to. If you want you can soda blast yourself with a portable gun with reservoir and a compressor to see the look. I have a higher quality model than below but this should work fine. $20 here in the states.
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