aluminium crank cases

[gerry maddenParticipant @gerrymadden53711]

[gerry maddenParticipant @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

[Jeff DaymanParticipant @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

[Michael GilliganParticipant @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.

[Involute CurveParticipant @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

[Neil WyattModerator @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.

[Ian Skeldon 2Participant @ianskeldon2]

DO NOT USE OVEN CLEANER,

and don't ask me how I know

[ronan walshParticipant @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.

[thaiguzziParticipant @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.

[Tim StevensParticipant @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

[gerry maddenParticipant @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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