radiator leak repair
A friend of mine has an RV12 and has had 2 radiator failures. He's 87 and loves to fly, so I wanted to help him get back in the air. His newest radiator had a small pinhole leak on the lowest row of water tubes. It was coming from a spot where the tiny fins are attached to the tubes. The repair method I chose to use may not be long term. Only time in service will reveal if it's a good method to salvage an existing bad radiator. I cut out a small area of the outside of the tanks to gain access to the lowest water tubes. Once I had access I used a very small stainless steel wire brush to clean off the aluminum around the water tubes. After that I carved 2 small pieces of balsa wood to be inserted into the water tubes. The wood plug is slightly oversize. Balsa is soft and it's easily compressed using needle nose pliers. I squashed it to the size needed to fit into the water tube. The balsa expands once it's pushed into the tube to tightly fit the tube. I pushed the wood in about 1/8th inch below the end of the tube. I used regular overnight cure J B Weld epoxy to fill in those 2 water tubes and then built up a mound of epoxy over the 2 tubes to encapsulate them. By doing this on both ends of the radiator you prevent any water from going though those 2 lower tubes. After everything had cured for a minimum of 24 hours, I welded patches over the areas I had cut out. J B Weld is good for up to 550 degrees F. once fully cured. Do NOT use the Kwik Set J B Weld for this type of repair. It does not have the same tolerance for heat as the slow cure J B. When I did the welding, I did it in short increments and cooled the area immediately with a wet rag to keep the heat affected area below what would potentially damage the J B Weld epoxy. Once it cooled, I did more welding and repeated the procedure until everything was fully welded. My friend has only flown his RV twice since the repair, but so far it's OK. He flies at least 3 - 5 times per week. If it starts to leak again, I'll post something in this thread. He'll likely replace the radiator with the new improved version from Vans once they become available. For now, he's very pleased that he can fly again.
Cheers
Enzo