ReplyIts hard to say what it is made of. I would say its probably got a lot of zinc in it to make it flow in thin sections. It looks to be useless the way it is. The only other option is to use something like Belzona ( I am not sure how it is spelled) it is like an epoxy and is many times used in pumps to protect an area that gets cavitation. Usually when used for that purpose the surface is roughed up to help it stick better. It will also repair the sealing surface .
If it were mine I would probably try striking an arc on it and if it looks good go ahead and weld it. If not I would use the Belzona. As far as getting rid of oil and such out of the metal . The only sure way is to heat it till it stops smoking then clean up the surface by hand or sand blast the surface after heating. The problem is aluminum and aluminum alloys do not give much warning before they melt into a blob so I would use indirect heating and I would stand right there and remove it from the heat as soon as it stops smoking. By indirect heating I mean I would not put a flame directly on it. If you do part of it will probably over heat. I would put it on a hot plate with a piece of 1/4" steel under it and sit and watch it . If it is fairly large you might need to put some insulation over it to keep the heat in but try to make it so you can still see part of it to tell when it stops smoking. A BBQ grill works pretty good too but you have to keep a close eye on it somehow. I would still put a piece of steel under it to keep the flame away from it even in a BBQ grill.
You will find that die cast and investment cast aluminum are dense and not much can get into the pours . The sand cast stuff has more problems with absorbing oil and contaminents. Non the less its better to be safe than sorry.
Originally Posted by Hobbytime
