Date: Tue, 23 Mar 2010 15:19:22 -0400
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Solder cracked steel coolant pipe?
In-Reply-To: <870131.33302.qm@web33508.mail.mud.yahoo.com>
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At 12:53 PM 3/23/2010, Robert Keezer wrote:
>Ok- So I have a friend who came over yesterday and soldered a one
>inch crack in one of the steel coolant pipes which cracked above the gas tank.
>I don't trust it, but he persuaded me.
Dear Robert,
I don't either. Whatever stress split the pipe may still be
operating and a soft-solder butt joint has very little strength.
If the split is along the length of the pipe I would recommend either
brazing (which may be difficult now that there's solder there) or
making a patch that fits the curve and extends a half inch or more
beyond the split on the sides and an inch or more on the ends. I
would form this closely to the curve of the pipe.
I would drill a hole -- 3/16 or 1/4 -- at each end of the crack to
give stress relief.
I would then polish the pipe shiny bright in the patch area and tin
it using plumber's solder and plumber's flux (OR some strong and
fancy low-temp solder from jeweler's supply house; I think the brand
is Tix and the price is $$$). Likewise shine up and tin the interior
of the patch, and butter it lightly with flux.
Put the patch in place and apply light pressure. Heat the whole with
a torch until the solder liquefies and the patch settles into
place. Move the torch around and don't let things get red hot. Feed
more solder around the edges until it stops accepting it, then let it cool.
I would expect that to last a very long time.
But if the split is around the circumference of the pipe, I think a
soft-solder patch would not be strong enough, and you would have to
clean it up and braze a patch on. The three common brazing metals
are "bronze," "nickel silver" and actual silver which can be had in
several melting points. Any of them should work but the silver is
easiest. Airco or other welding supply house and ask for the proper
flux even if the rods are flux-coated. If you get low-melting
silver, make sure it does not have cadmium in it. A propane-air
torch should be able to reach the necessary temperature and a
Mapp-gas torch might. An oxy-acetylene torch definitely will.
An alternative would be to cut the pipe at the split and rejoin it
with a piece of 1.5" ID heater hose, silicone by choice (truck-supply
place). In van terms I would expect that to be "permanent" and it
would relieve any stress in that area.
Yours,
David