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Cleaning Aluminum Crankcase


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I'm beginning the restoration of my 1910 Mitchell with the engine... I have it stripped at this point and I'd like to throughly clean the crankcase. This is the first aluminum crankcase brass car I've done so I'm wondering if anyone has some suggestions as to the best way to go about it. I want it clean before I start on the machine work... I will probably bead blast the exterior (depending on how it cleans up) when the machine work is done but I don't like doing fussy work on dirty parts.

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Some aluminum crankcases were painted inside to seal them. I have seen this on Harley Davidsons as far back as 1930. There were remains of what looked like red lead paint in there.

So, do not be too surprised if yours were painted. You can paint them yourself. Have seen Rustoleum and Glyptol paint recommended for this.

The paint is to seal any porosity in the castings, help oil drain away faster and prevent sludge deposits from sticking.

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Without a doubt Vapour or wet blasting is the best way to clean aluminium.

The aluminium sump in the photos was BLACK and half a day washing with degreaser and then hot water and detergent hardly changed it.

An hour being vapour blasted and it looks like brand new. The machine uses a combination of high pressure water, air and glass beads and leaves the surface smooth and shiny.

The company that did my stuff rebuilds race car gearboxes and this is what they use on all the gearbox casings to bring them back to as new condition.

This is a demo of one in action. Wet Blasting | Dana Ridge

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I've been searching but so far I haven't found anyone remotely close that does this sort of thing... I don't think we even have an engine rebuilder in the area that I'd trust with a brass car crankcase. I'll keep looking and in the meantime try the solvent and paint remover.

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Al

I am refering to paint removers that contain sodium hydroxide a/k/a caustic soda a/k/a lye. Sodium hydroxide will etch aluminum and sometimes turn it black. I know there are paint removers with acteone or other base that will not react with aluminum. I just don't want JV or anyone else to get a jug of paint remover at the hardware store and glop it onto an aluminum part and find the remover contains lye after they make a mess of the part they are trying to clean.

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I'm aware of the caustic soda issue. Many years ago, when I was in the garage business, a nitwit at the local engine rebuilder dropped a couple of VW heads in the hot tank...

This is a preliminary cleanup only, just enough so that its decent to handle while I do additional machine work. When all the machine work is done I'll revisit the issue. One thing I am trying to avoid is the "over restored" look. This was not a top of the line car like a Locomobile. The castings are fairly rough and always have been... and thats the way I want the finished engine to look. Like it did in 1910.

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I used a pressure washer to get started

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Then put all the aluminum parts in a barrel with degreaser and laundry detergent on a 2x4 to let people rock it as they walked by.

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A few days later, an extra pass with the pressure washer and they were ready

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I would probably try soda blasting if I had anything available here though.

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A good point. There are considerable traces of aluminum paint on the crankcase. I've no opinion as to how old... though its clear that the engine hasn't been used in a very long time, maybe since the teens, and that it never ran much as the bearings are in surprisingly unworn condition. I wonder when aluminum paint was invented? I confess, I've no idea.

jp

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Some aluminum crankcases were painted inside to seal them. I have seen this on Harley Davidsons as far back as 1930. There were remains of what looked like red lead paint in there.

So, do not be too surprised if yours were painted. You can paint them yourself. Have seen Rustoleum and Glyptol paint recommended for this.

The paint is to seal any porosity in the castings, help oil drain away faster and prevent sludge deposits from sticking.

On many antique car engine crankcases that have not been messed around by enthusiasts, you can still see traces of a bright silvery aluminium paint. I have found this onSunbeam, Fiat, Lancia, 4 cylinder Cadillac and V8s, Packard, Mercer (both L-head and ohv Six, Rochester Duesenberg, and Napier. The 1911 four cylinder Napier has the clutch running in oil between engine and gearbox, and the silver paint was also inside the clutch chamber. The paint I found to exactly match what had been was in a spray can labelled "Bright Silver". These were American origin though sold and branded as Protec, which is a manufacturer in Adelaide South Australia. You should have little trouble finding the right stuff in USA.

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Thanks Ivan, et al...

This is all very interesting... especially as I have no access at this point to an untouched early car to examine... though now that I think of it, I believe a 1905 Cadillac engine I rebuilt for a friend years ago was also painted with aluminum paint.

I did a patent search on "aluminum paint" between 1890 and 1910. While I didn't read them in any detail, its clear that a variety of aluminum based paints were readily available. That is consistent with the condition of this engine. While it has certainly been taken apart and neglected, it clearly has never been cleaned or "restored."... I suspect this answers my original question. The best idea is probably to get it chemically clean and then paint it, as it almost certainly was when new. Its a lot easier too.

Machine tools built at the same time (from the 1890s to the 1920s) were always painted, usually with a very thick "sanding" paint something like a cross between body filler and paint. (A good deal of effort has gone into figuring out what the material was by antique machine tool collectors.) The machines were then sanded and finish painted, all this to hide the imperfections in the castings. I see no evidence that was done on the Mitchell but it would not surprise me to find out it was one on some cars...

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  • 7 years later...

I am a fan of undiluted Simple Green (matched to time and patience) and for eons a restoration shop here in town would use Easy Off Oven Cleaner or whatever other oven cleaner was on sale or handy  - I have not tried it, but saw it done many times and looked great. 

 

One of those cars that had oven cleaner used on the block went across the podium at Pebble Beach Concours this year (in re-restoration though they glass beaded)

Edited by John_Mereness (see edit history)
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I'm not sure on crank cases but I have stuck many aluminum and pot metal parts in evaporust and it cleans them incredibly well of everything but paint and in some cases even that if there is any oil or oxidation behind the paint.  It's an awesome degreaser if you can submerge the part.  Also cleans the rust off any iron parts you might not have removed.  Try throwing scuzzy old oxidized door handles in a vat of it.  They come out incredibly clean.,  Even the nickel plated ones. 

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I have a machine shop locally that has some kind of pressure cleaning booth/machine, and they've cleaned a couple of early aluminum crankcases for me with no damage.

 

And, as mentioned, most aluminum had aluminum paint daubed on it, not a shiny finish but rather daub it on and rub it finish.  The interior gets coated with Gasoila or, I think it's called now, Glyptol.

 

I have a crankcase that was cleaned, then machine work done to it which resulted in some residual oil on the surface.  I find that the spray cans of electronic contact cleaner work great, working small areas and quickly, spray on and wipe off immediately.

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Hi, Thanks for your thoughts and ideas. I forgot to tick the 'follow box' and did another search and found that Joe Puleo had posted again in 2014.

 

After reading the above and the comments in this post I am even more confused! I searched 'Easy Off Oven Cleaner' when I checked the specification it said don't use on aluminium?!?

 

2 hours ago, John_Mereness said:

I am a fan of undiluted Simple Green (matched to time and patience)

 

Do you mean it takes time and you need patience? There seem to be various types of this product. Which one would you suggest?

 

2 hours ago, auburnseeker said:

I'm not sure on crank cases but I have stuck many aluminium and pot metal parts in evaporust and it cleans them incredibly well of everything but paint

 

With my search on Evaporust there is no mention of using it on Aluminium. It maybe worth me trying it as there are steel studs and valve adjusters that need to be removed from the aluminium crankcase. Perhaps it may help unfreeze these?

 

Here are some photos of the crankcase that I would like to use as it is in a lot better condition than the one that I already have for my 1914 Humberette water cooled V-twin engine.

 

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It is roughly 18" in diameter.

 

Your ideas after seeing the photos would be appreciated.

 

 

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I recently had to clean up an aluminum transmission case. It was a TH400, so obviously half a century newer than the parts being discussed here, but it had been sitting outside on the ground for a long time. Mud, caked grease, and corrosion. I used my soda blaster. It cleaned the casting incredibly quickly and did an amazing job. The soda had no effect whatsoever on the base aluminum and the cleaned part looked great. I then washed it thoroughly with soap and hot water to remove any residual soda (including cleaning out all the internal oil passages in the casting) and blew it out with compressed air. I was impressed by how well the soda blast worked, how little effort it took, and how the part came out. The outer surface will not have the "as-cast" bare aluminum finish that you get with glass beads, but I was more concerned about not getting glass beads inside the many passageways in an automatic trans case.

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We have a shop locally that does dry ice blasting and I was going to use them for the aluminum crankcase on The Car Which Shall Not Be Named. No disassembly required, light abrasion leaves a proper-looking texture on it, and since it's dry ice, there's no abrasive left over that can get into working parts. I have not used them but they are scheduled to give a lecture and demonstration this winter here in our shop for one of our weekend seminars and I'm eager to see what they can do. It might be worth exploring.

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