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MG TD TF 1500 - Radiator branch pipe

I was practicing brazing today (with some success). One of the parts of my heater rebuild project is to braze on an additional 5/8 pipe to the radiator branch pipe, as a return from the heater. I'm wondering while I'm working on the branch pipe whether I should have it powdercoated, or paint it. I'm thinking of anything to help reduce corrosion in the future. Can anyone recommend any kind of coating for the interior of the branch pipe?
I'm thinking of brazing a piece of copper pipe to the branch pipe, and then connecting to a stainless steel pipe to run under the manifold and come out at the firewall, and then hose into the back of the heater.
Geoffrey M Baker

Actually, Geoffrey, to reduce (and, in fact entirely eliminate) corrosion in my LBCs' cooling systems I've begun running Evans Waterless Coolant NPG+ (I think they've recently changed the name to "High Performance" coolant). It consists of mostly Propylene Glycol and it's not a water-based product so it prevents virtually any sort of corrosion. I find it cools slightly less well than the traditional anti-freeze/water mix, but it's pretty dang close, and for our environment here in the Philadelphia area it works great. Plus, since it will not boil until much higher than engine temperatures, it won't ever boil over, so even if your engine gets hot you're still not gonna get stranded with a steamy rad. It also won't form bubbles on the interior cooling jackets so it cools more evenly.

Not sure how it will work for you in AZ, but you might give it a try. It ain't cheap, but it does work well and could theoretically preserve an engine's cooling system indefinitely.

http://www.evanscooling.com/

Here's a segment from Jay Leno's Garage on the stuff.. apparently he's been using it for 16 years in his cars...

http://www.youtube.com/watch?v=t7PykrgzWPQ

Kevin McLemore

Geoff, you might want to reconsider the idea of brazing for a piece of copper pipe. The temperatures required for brazing are high enough to melt the copper pipe. I learned that the hard way.
You might want to check the archives for past threads on the Evans coolant. Bud
Bud Krueger

Bud, I'm going to try stainlee steel and see if I can braze that
Geoffrey M Baker

Good luck, Geoff. It's my impression that the welding of stainless steel is a job left to the experts. I'm not so sure that brazing is even possible where stainless steel is concerned. We have at least a couple of those experts on this forum. Bud
Bud Krueger

supposedly you can braze stainless if you use the correct rod (e304?)
Geoffrey M Baker

Its not the rod, its the preperation, the cleaning, the flux and how you handle the gas mixture.

Stainless can have a heavy, naturally occurring, oxide coating. That must be removed first, to get adhesion.

In the heating process a new oxide can easily grow. Strangely enough it, the oxide, likes a hydrogen rich or reducing flame.

We used to make brazing fixtures out of stainless. To stop the braze from sticking to the stainless we sent them through a furnace with a "Forming Gas" atmosphere. They came out a lovely shade of green with a tough oxide that nothing stuck to (Forming gas is some times called dissociated ammonia. It a mixture of Nitrogen and hydrogen.)

Normally when I braze I use an Acetylene rich, or reducing flame to help keep thing clean. I would not recommend doing that with SS. Stick to a neutral flame.
I would also use the black flux which is more active than white flux.

Finally I would use a silver braze rather than brass based braze.

However I don't think SS would be a good way to go. Corrosion is best controlled by using similar materials. I think steel would be perfectly fine, it would have less potential to corrode and I believe it would last a long time.

On the subject of brazing copper. I have some brazing rod with about 4% silver that is designed for copper. (Refrigeration copper tubing)
I could send you a piece if you want to go that way.

Jim B.

JA Benjamin

Thanks, Jim. As a neophyte I was getting pleased with my success at brazing with my Home Depot kit. Then I tried to braze a piece of steel brake line into a brass plumbing fitting. I shed tears as I watched the fitting begin to melt. Bud
Bud Krueger

I guess I will just go back to mild steel and see how that brazes. I'll just use No-rosion to protect the metal.
Geoffrey M Baker

Bud,
Your brazing effort was, no doubt, generating too much heat. Rather than brazing you may have more success with silver soldering. Use a high silver content solder. I find 54 to flow the easiest. Home Depot doesn't carry silver solder (I know, I work there), but any good welding supply house will have it. Don't get grade 45, as that has a higher melting point and doesn't flow as nicely as 54.
Lew Palmer

Thanks for the pointer, Lew. I may try some silver soldering to see what it's like. I solved my brake line gauge problem by using a galvanized pipe fitting. It didn't melt. Bud
Bud Krueger

A bot of terminology here.
"Silver Solder"

It used to be we all new that this referred to a High silver content alloy of silver and copper with minor quantities of other things, like cadmium and Zinc to improve flow and further lower the melting temperature.

This was some times called "Hard Solder"

However there is now soft Silver solder with a small amount of silver in it, less than 4%. Usually with the balance mostly tin.

This should not be confused with the"Silver Solder" that Lew and Bud mention. Technically its a silver braze since it melts at over 800F.

In the attached picture is a shop made floor board T-Nut for the front floor boards.

Its all 303 or 304 SS. Its on the right with a OEM on on the left.
If you look carefully you will see the Silver braze ring around the 5/16 BSF post and the 1/8" points that hold it from turning.

Just to show that you can braze SS.

Now the silver braze melting temperature is several hundred degrees lower than the brass braze. This may lead to having an easier time in brazing.


Some years ago I got a good deal on about 10 oz of 1/16 silver brazing wire On eBay. I have much more of that than the brass and its finer so I prefer going that way.

Jim B.



JA Benjamin

This thread was discussed between 01/11/2014 and 02/11/2014

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