overflow tank plumbing

[Doc Dave]

I am getting ready to plumb the firewall mounted overflow tank on my '52 power wagon, "kirkwood"
On the radiator, the existing overflow tube goes down along the side about 10 inches and ends.
I was thinking about using copper tubing and use a union with the existing tubing after flaring both . Then run the copper back to the overflow tank. I am thinking copper would be good since it would not be under pressure like brake line, and also copper is not like steel tubing as far as rusting goes.
Does this sound right? Or should I use steel tubing?

[MoparFreak69]

You can use pretty much whatever you want to use, the coolant/antifreeze will have rust inhibiting properties so you need not worry about it rusting from the inside out. You are probably planning on coating the outside with paint for appearance so no need to worry there. I think my deciding factor would be price. What is cheaper? Go with that.
As far as using a union for the connection, that is perfectly fine, however there is no need to flare prior to installing it. They contain a small brass double beveled ring that smashes into the tubing to lock onto it and prevent leaks. Just make sure the tubing it cut nice and square and there isnt any burrs to prevent the tube from sliding all the way into the union fitting. They use unions on fairly high pressure air tubing made out of plastic (150psi range) without fear of failure so I am sure that your 0psi overflow tube will be a cakewalk for it.
Another option to consider is just running a rubber hose from the existing overflow tube to the overflow tank. That is how pretty much all OEM systems function and they work just fine.
Whatever your preference, thats all that matters.

[Tom Petroff]

Dave, as far as I know copper is what was used.
A compression fitting is what you want to connect the two lines.
Then it's routed down along the frame rail to the tank.
TGP

[Doc Dave]

Thanks Mopar and Tom,
So that it looks original, I will run "hard" line, although I agree a rubber hose would be a lot easier.
I think I will use copper tubing in part because it is easier to bend, and will use the compression fitting you all suggested. That also will eliminate the need to manipulate a flare tool onto the existing overflow line.

[Rich in Colorado]

Dave,

I have a overflow on my '63. It is routed and conected as Tom said. But mine has a 3 or 4 inch loop in the copper tubing about half way between the tank and the rad. I don't know if that is original or not. I assume it is to absorb any vibration.
Rich

[Doc Dave]

Rich,
MY power wagon parts manual shows that circle loop. I agree that it is to absorb vibration. The manual shows it within a foot or so to the overflow tank.

[Rich in Colorado]

Dave,
Yes it is closer to the tank. I was going from memory in my first post. I went out and looked and it is much closer to the tank, right below. Sounds like you know about it; where it belongs. But if you want a picture or measurements let me know.
Rich