Expansion Tank Repair

[simplyconnected]

Some years ago Johng (John Goulet) was frustrated that he couldn't keep his expansion tanks from leaking. That got me going and I asked him to send his leaking tanks to me. He sent two.

After assesing the damage, I could see why these brass tanks crack and leak. Over the years the cooling system pressure tries to turn them into a ball. They flex too many times causing the solder joint to give up. So, I tried something new. I drilled three sets of holes through the top and bottom of the tank, sent bronze rods through, and soldered the ends. No more flex and no more problems. CLICK HERE for the site. - Dave

[frank58]

what a great idea with the brass rods to control expansion. what was the alloy you used to solder with? I've had to re-solder a small seam leak on my old '59 but that was 50 tears ago (OMG) but luckily no cracks. but after 50 more years of expansion I see the stress turning into cracks.

[simplyconnected]

Frank, all the box stores sell 'silver-bearing' solder for sweating rigid copper tubing. I'm not opposed to using lead (because I'm an Electrician by trade) but the new solders include antimony with tin which is stronger, with a slightly higher melting temperature. They sell matching paste for this solder which is different from 'flux for lead solder'. The trick is, keep all oil including finger prints away from your solder job. I clean everything with lacquer thinner on a rag. Perfect for this application. The new solder and paste prices are good too.

Early Squarebird expansion tank halves have a smooth surface, top and bottom like the first one in my site. Later tanks have ribs stamped into the 'clam shells' which helps with rigidity but still no cigar. You are right about 50+ years of flexing, sometimes twice per day. I don't know why nobody else thought of using 'tie rods' (which is exactly what they are). Using three rods is far more effective than two but either way, 'bloating' simply can not happen any more which makes the same solder seams even stronger. The cost of this repair is nearly for free if you have the materials hanging around the garage.

I know restorers who simply re-solder every time their tank leaks. Two things happen; the leaks come back and they are afraid to travel too far away when it happens. This fix is permanent and worry-free. - Dave