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The low temp "welds anything" filler rods, if I remember correctly, contain Zinc. Which I believe sticks to aluminum but does not actually form a weld. Years ago I used big GM evap cores as oil coolers and in one case as a water radiator. Came from a junk yard off of the aluminum pile. One still hooked up and holding pressure would be ideal. But more expensive. Used they may have lots of oil in them. (compresser lubricant)

So clean extensively with Ketone of similar. Wrap with wet towel right up to the edge of the top. Do not fill with water. Steam will ruin the weld. I cut off the tubes and welded on AN fittings. Very nice look. Pressure test to twice the expected oil pressure before use. Should hold pressure over a weekend.

I forgot the actual alloy number of the low temp filler rod from the welding store. But it is actual aluminum filler rod. Wipe off each filler rod with wet or dry 400 grit and clean with ketone rag. Use a stainless wire wheel on the area on the evap to be welded. Weld about 1/4" at a time and let cool to room temp. Lots of amps/short time. This is welding on the thick flat end plates. Formed end tanks can be very thin.

No leaks. No distortion. Looks like a factory piece. ..........Lynn E. Hanover

In a message dated 2/22/2021 6:26:16 PM Eastern Standard Time, flyrotary@lancaironline.net writes:

https://www.alumiweld.com/

is one brand, but most local welding shops will carry some version of the stuff. I used it to braze my intake tubes to 1/4" plate, but I have no idea whether it will stand up to the intake pulses & vibration with the engine running. I can tell you that the stuff isn't the magically easy to use stickum that it seems to be, when you're watching the carnival barker at SNF. The stuff I used was marginal on thick stuff with a propane torch (might not be a factor with the heat exchanger). You'll almost certainly need a wood handled stainless steel brush to free the corrosion on the base metal while the torch is applied to the molten brazing material.

Have you thought about hitting Barry up to take a look at it? ;-)

Charlie

On Mon, Feb 22, 2021 at 3:04 PM Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:

Some time ago Ed Anderson recommended some (rather expensive) DIY alum
welding or brazing rods that he had good success with.

I really need to add some alum tubing to the ends of the evaporator core
tanks (and close off the existing tubes going into the tank sides).

I'm worried that If I try to do that myself that I will disturb (weaken)
the existing core brazing/welds.

I assume that if I take them to a (Tig?) welder he'll be able to do it
so heat won't spread (or maybe submerged in water)?

Any advice?

BTW, I'm now unable to find the exact same cores on eBay and would
rather avoid having to re-do the fiberglass inlet ducts. So I'll have to
take the plane out of service to do it and to not mess up the cores.

Finn

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