When repairing an aluminum radiator, you have to consider many things. Before you can repair the aluminum radiator, you need to find the leak. Once the leak is found the aluminum radiator must be cleaned for the epoxy to take hold. Aluminum radiators are hard to weld which makes epoxy the most inexpensive way to fix them. You need to be very careful because epoxy is a chemical and very dangerous. Make sure you handle it properly and keep it away from animals and children. Here's a step-by-step procedure in applying epoxy to an aluminum radiator to fix a leak and to properly seal it.
Step 1 - Engine Cool Down
Make sure the vehicle is off and has cooled down to eliminate the pressure. Disconnect anything that is in the way of the leak and if needed remove the radiator so it's easier to work on. Look for the leak in the aluminum radiator and, once you find it, clean around the area with a good cleaner. It has to be cleaned very well so there is no dirt or grease around the leak or the epoxy won’t have a strong bond. Sand area around leak for better bonding of epoxy.Once you have it cleaned let it dry. Wet surfaces aren't good for the epoxy either. Let it dry as you get ready for the next step, and get the epoxy ready for bonding.
Step 2 - Fix the Leak
Some epoxies come in strips or chunks. You might have to break off the amount you think you will need depending on your leak. You knead it with your fingers to get the epoxy ready to apply to the leak. The longer you knead it, the softer it becomes, which makes it easier to apply. Make sure you cover the whole leak, and if you have any excess, wipe that off. Don't rush this process. Remember, this needs to be applied good so once the pressure builds up in the radiator it won’t bust through. Once it’s applied let it dry. That could take about an hour or so to harden but for best results, let it dry overnight.
Step 3 - Check your Work
Before you do anything make sure you have the proper amount of antifreeze in the radiator and be sure if you unhooked anything to hook it back up. Double check your work making sure the epoxy has a good strong hold. Start the vehicle and look for leaks. Let it build up some pressure to be sure the epoxy is holding. Once you have it running for 5 to 10 minutes and you have no leaks you are good. Make sure you clean up and wash your hands very well with a good cleaner to get any epoxy off your hands because epoxy is very toxic. And please clean up any antifreeze or any other chemical that might have spilled. All chemicals are toxic to animals and bad for the environment so dispose of everything properly.