They say it is possible to well or braze aluminum casting with an oxyacetylene welding equipment and a flux coated aluminum filler rod.
I wanted to repair (or rather fill up) a pencil size hole on the oil pan of my son’s car engine. The oil pan was situated so low under the car chassis that it was holed when one tyre hit a pothole.
I have seen any one welding aluminum casting using an oxyavetylene torch but I had a feeling I could do it. If it could not be done there wouldn’t be any aluminum filler rod on sale. I bought one rod whic was about three feet long and that cost me Rm4.50.
After cleaning the area around the pencil size hole at the bottom of the oilpan with sandpaper I lighted the torch and adjusted it for a reducing flame. As it was impossible to know that the area around the hole had reached the appropriate temprature I introduced the tip of the rod into the flame . The rod melted but it just wouldn’t stick to the surface of the aluminum casting. Glubules of molten aluminum just just balled up and fell through the hole.
By this time the whole casting was too hot for me to clean up the area around the hole again