Soldering repairs for radiators include fixing leaks, cracks and holes. Automotive radiators are commonly made of aluminum, brass or copper, which are metals that can be patched and repaired with solder. Performing soldering repairs many times on the same radiator is possible, provided the damage is not very extensive.
The first step when repairing a radiator is to ensure all work surfaces have been properly cleaned and thoroughly dried. Drain the radiator before removing it from the vehicle. Remove paint using a steel grinder or wire brush. Cleaning a radiator carefully ensures that cracks and holes do not grow larger. Using a degreasing agent or brake cleaner on work surfaces ensures better adhesion between the solder and radiator.
Use a high-wattage soldering iron capable of producing the heat needed to melt thicker gauges of soldering wire. Hobby irons and thin solder wire are not ideal for repairing a radiator. Irons producing 60 watts or more should provide enough heat. Heat damaged areas of the radiator until they are hot enough to accept the solder easily. Then, apply solder to the surface until the crack or hole has been completely covered. Grind burrs, sharp edges and solder balls from the radiator using a grinder or brush once the solder has cooled and set.