[TR] Radiator repair in-situ, TR4

Brian Jones tr4zest at gmail.com
Sun Sep 19 08:39:19 MDT 2010


Just sharing a modest success.

I have a TR4 with the long-neck header from the TR3 set-up. These necks are
prone to crack, and true-to-form, mine developed a weeping fissure.

Having installed an electric fan to the back of the radiator and a
temperature-sensor between the radiator's fins, I wanted to see if I could
fix the crack without pulling the radiator. So, I drained the radiator and
removed the paint around the 0.5 " crack and saw that the joint was
soldered. I had expected it to be brazed. Solder it is then. Acetone, then
flux, then solder.

Its a little bit of a fiddle to get the joint warm enough to let solder flow
without clearing the joint of all its solder. I switched from a propane/oxy
torch to just a simple propane torch to better control the heat at a lower
temperature.

With the joint soldered, I needed to pressure test.

I had previously removed the upper hose to save it from the heat. I closed
that port with a cloth and thick vinyl, secured by the inlet hose's circlip.
I found a cork bung to fit the radiator cap's hole and connected an air
compressor (one to put air in tyres) to the rad's overflow tube where it
ends, beneath the frame.

As the compressor pressurised the radiator, I put soapy water over the
joint. I saw a small bubble develop very slowly, so I knew I was not done. I
re-cleaned everything (acetone, flux) then re-soldered the joint. Second
time, I saw no bubbles and saw the pressure on the compressor's digital
gauge gradually climb to 6 lbs.

All re-filled with coolant, a quick test-drive and the joint was dry. Next
weekend, I'll prime and paint it.

So, if your TR4 (or TR3) weeps in the same way, simple pipe-soldering
'skills' can get it done.

Brian
Valley Forge, PA
TR4 14455 L (O)


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