Advice on welding radiator water pipe

[srgore67]

I am planning to weld the hole closed on a Mitsubishi radiator water pipe. You can't find these pipes very easily and this is a pipe I'm adapting to fit my 1990 eclipse. I cut the smaller side pipe off and it has this gold looking finish where the manufacture welded it. I'm thinking it's silicon bronze? The pipe is metal so I'm not sure why they didn't weld it with metal filler. I would like to mig a steel circular metal patch on it which is bigger than the current hole and almost covers up the gold filler that was used. My question is can I just weld it with steel mig filler wire or do I have to use some special wire/rod ?




Thanks in advance!!

[Rambozo]

You are right it looks like a brazed joint.
You can either braze on your patch, or if you want to MIG it, you will need to remove all the bronze or it will contaminate your weld.
Since there is likely braze metal on the inside that might be hard to remove, you might want to make your patch slightly oversize, so you don't suck in bronze from the inside.

As to why the factory did it that way, since brazing is a lower melting temp than the base metal, they could just insert the fitting into a hole, then spot heat it or run it through a furnace to braze it up. If it was welded it would require a fixture to hold both pieces in alignment for the weld. That would cost a lot more to do. Braze is more than adequate for that application.
I can't tell from the picture if that is carbon steel or stainless. It would be best to match your patch and MIG wire to the base metal, or braze it.

BTW you can also MIG braze with the right wire and gas.