aluminium crank cases

This topic has 10 replies, 9 voices, and was last updated 10 June 2017 at 23:10 by gerry madden.

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9 June 2017 at 15:45 #34351
gerry madden
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@gerrymadden53711
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9 June 2017 at 15:45 #301803
gerry madden
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@gerrymadden53711
Hi, I have some aluminium crank cases from a small engine that have been in a damp environment for a few years and have developed that patchy white dusty coating.

I'm sure it will rub off with a bit of effort but I'm just wondering if there is a much more efficient way of cleaning these things up without leaving abrasive scratching marks in all different directions ?

Gerry
9 June 2017 at 16:00 #301805
Jeff Dayman
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@jeffdayman43397
You might try a motorcycle engine repair shop for glass bead blasting. It will leave a nice clean matte finish on your aluminum and not mar any details or leave scratches.

A coat of good clear car wax afterward, or some clear urethane spray clearcoat on outer surfaces, will keep the parts looking nice. JD
9 June 2017 at 16:03 #301806
Michael Gilligan
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@michaelgilligan61133
Gerry,

The best way that I have found is to use a GaryFlex block [which is rather like the old school 'ink rubbers'], with Solvol Autosol polish as 'lubricant'.

Yes, it's abrasive … but very mildly so.

MichaelG.
9 June 2017 at 17:33 #301809
Involute Curve
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@involutecurve
I vapour blast all my crankcases as a matter of course, the finsih is as new, but you must make sure you clean all oilways etc afterwoods.

Shaun
9 June 2017 at 20:14 #301832
Neil Wyatt
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@neilwyatt
I used my ultrasonic cleaning tank with a 'sensitive metals corrosion remover'. Not obvious from these shots, but it removed white 'bloom' as well.
9 June 2017 at 23:36 #301845
Ian Skeldon 2
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@ianskeldon2
DO NOT USE OVEN CLEANER,

and don't ask me how I know
10 June 2017 at 00:37 #301850
ronan walsh
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@ronanwalsh98054
I boiled up some old cases in water with normal washing powder in it, the cases came out like new. But i tried it with a separate set of case sometime later, and they came out a blackish grey colour, not nice at all. Someone said it was because of the silicon content of the aluminium reacting with the contents of the powder.
10 June 2017 at 06:26 #301854
thaiguzzi
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@thaiguzzi
Posted by Involute Curve on 09/06/2017 17:33:22:

I vapour blast all my crankcases as a matter of course, the finsih is as new, but you must make sure you clean all oilways etc afterwoods.

Shaun

+1. Wot he said.

There is no better finish.
10 June 2017 at 11:37 #301894
Tim Stevens
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@timstevens64731
Ronan is correct – some Aluminium alloys contain a high proportion of silicon, and when the Al is eaten away (by eg washing soda, or worse, caustic soda) the Si is left as dirty smudges. This is a major reason why anodising does not give good results on such alloys.

Aluminium does not rust
It crumbles to a greyish dust
And most of all what you can see
Consists of Al two O three

Cheers, Tim
10 June 2017 at 23:10 #302006
gerry madden
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@gerrymadden53711
Well as usual some great info there. I didn't know about vapour blasting did some research and I'm impressed ! What's more there's a small business not far away from me that does it so I'll be visiting them next week. And by the looks of it, there's quite a few more bits and pieces they can do besides my crank cases.

Thanks all for your input.

Gerry
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