Magnesium Cleaning
 

After cleaning at the local machine shop, my case halves came back still with traces of what looks like electrolysis not removed. I experimented in a very small area with a Dremel and bronze wheel and it comes up nice and bright, but is this okay to continue with? Is there possibly a protective coating of any sort on the mag parts, or do they just naturally turn gray with age?

Any other suggestions? The "electrolysis" is on parts of the throttle body exteriors as well.

Thanks
Francis Kennette
74 Carrera (euro)

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Are you talking about the mating surfaces? Be very careful cleaning those, as you don't want to place any scratches on them.

As for the interior of the case, yes - you can go to town cleaning it. I personally would not use any power tools inside the case though, as I would think that this would create too much powder and debris that may get into the inner case passages. I would stick with wire brushes (by hand) and carb/brake cleaner. If you look on page 125 of the Engine Rebuild Book, you will see what a corroded case looks like before it's adequately cleaned.

-Wayne

There are a few different processes used for magnesium. On Hewland gearboxes a coating from Dow Chemical can be used. On brake calipers a polymer coating can be used. You should contact your local Dow or helicopter repair center and see what is on offer. I've not seen a mag case coated, but I don't see any reason why it could not be done.

Thanks for replies guys, but I'm referring to exterior of the case for cleaning (not the mating surfaces - they're okay w/ just scotchbrite & alcohol cleaning).

I've started doing the job w/ Dremel & small bronze wheels - a slow process but it comes out quite nice.

Francis

Same concerns - make sure nothing gets inside of the case. I would wait to clean the outside of the case until after the inside was sealed up...

-Wayne