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From: John De Armond
Subject: Re: soldering exhaust manifold?
Date: Tue, 17 Apr 2001 18:46:19 -0400

y_p_w wrote:

> Charles wrote:
> > Can copper be used as solder in this case?


> You wouldn't be able to apply copper with a soldering
> iron.  I recall one recent auto NG thread where the
> consensus was that cast iron exhaust manifolds can't
> even be welded.

Boy, I'm glad no one told me that because I neve would have been
able to weld all the manifolds that I have.

If the manifold has seen leaded gas, it needs to be bead blasted to
remove the lead residue.  Then, if the task is to fix a crack, each
end of the crack is drilled to stop propagation during heating.  The
crack is then ground to a vee to about 1/2 to 3/4 depth.  Then the
whole manifold is preheated in the range of 500-700 deg.  Finally, a
pure nickel rod is used to weld.  Either stick or acetylene is fine.
Stick is faster but acetylene gives more control.  Even TIG is
suitable.  Ideally the welded manifold will be placed in a kiln and
heated to a dull red (1200 deg or so) to stress relieve the weld
before slow cooling.  If the last step is not possible, the manifold
should be packed in ashes, kitty litter, vermiculite or similar
material to slow the cooling and avoid thermal stress as much as

From: John De Armond
Subject: Re: soldering exhaust manifold?
Date: Wed, 18 Apr 2001 17:04:35 -0400

y_p_w wrote:

> Well - fron what I gathered, the consensus was that an
> attempt to fix a cracked exhaust manifold would be a
> rather temporary fix.

Just another example of the consensus not knowing jack.  Any welder
worth the title can weld cast iron with no problem at all.

>If you have to have someone do
> it for you, the costs might be high enough that it
> would be worthwhile to have it replaced anyways,
> since exhaust manifolds tend to be cheap.  Or so it's
> been said.

I would expect to pay little more than the welder's minimum fee
which is usually around $35 here.  he'll probably preheat the
manifold with a rose bud instead of an oven and may not normalize it
post-weld but neither have much significance for ordinary exhaust
work.  My work mostly involves fabricating cast iron turbocharger
adapters where physical strength and resistance to extremes in
temperature are required.


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