DIY Aluminum Radiator Repair

Who had repaired an aluminum radiator themselves and what did you use? Epoxy or low temp (MAP) welding/soldering are my options but need some input from anyone who’s attempted to repair things themselves. Muggy Weld 1 looks promising but pricey (but I would buy if it’s as good as promoted) and the Harbor Freight stuff has good reviews. Various epoxies might do the trick. Anyone?


Low Temperature Aluminum Welding Rods, 8 Pc.


Super Alloy 1 Low Temp Multi-Metal and Pot Metal Solder | Muggy Weld

Yes. I repaired an aluminum radiator by pouring 2 ton strength clear epoxy into the cooling fins to make about a 1" square around a small hole or crack. I don't remember, but I probably poured it in from both sides. It never leaked again.
I bought a new 1986 Trans Am that my wife drove. The front opening for the radiator was underneath the nose with a little chin spoiler, maybe 2" wide, at the back edge of the opening. One day when she met me for lunch, I noticed that spoiler was missing screws and was dangling in the center. I took it off until I could get more screws. Big mistake. It had electric fans for the radiator so I never expected any problems. Later that day the top radiator hose exploded. It would cool sitting still, but without the spoiler, it would not cool at speed. Replaced the hose but now the aluminum radiator was leaking near the center. A new aluminum radiator was something like $400 in 1986. Radiator shop said it could not be repaired so I figured I couldn't lose anything by trying.

I have tried the aluminum rods at Harbor Freight, which are a copy of the Muggy Weld. They never stuck for me. One attempt was aluminum sheet roof, the other a cast aluminum convertible frame (my 1964 Valiant). I abraded to shiny aluminum and tried fast, rubbing the rod as youtubes show. Perhaps it works better on aluminum extrusions, like the demos.

If you try those HF rods, use a new SS brush to clean the aluminum you are planning to solder. I have a dedicated SS brush that I use with those solder rods, and they work pretty good. I've used them on several aluminum projects. I wouldn't trust them on anything too important though. I'd also be afraid to go near an aluminum radiator with a mapp gas torch though - with how thin the tubes/cooling fins are.