From: John De Armond
X-Source: The Hotrod Mailing list
Date: Aug 1992
Subject: Re: rodding a radiator

>does anyone know how to rod a radiator.  the one on my 56 chevy is
>clogged.  how much work is it and is it worthwhile doing it oneself.
>or does the ultrasonic cleaning of radiators work better or as well.
>dxs

Every radiator I've ever rodded leaked afterwards.  Usually by the time
the core is plugged, it is also so corroded that the crud is plugging the
leaks.

if you want to try, first you unsweat the tanks.  I use a MAPP
torch to melt the solder and an air hose to blow it away. You have to do
this without melting the tube solder.  Then get a rectangular rod
(I use a stick of Silphos copper braizing rod) that will fit the tubes,
apply your favorite decalcifier chemical and rod away.  I've used
both phosphoric acid and something from the hardware store called CLR
(phosphoric acid with a few goodies and a LARGE price tag.) with
equal results.  When you're finished, clean everything up,
apply acid flux to the tanks and the core , reinstall the tanks and
sweat shut with 50-50 solder.

I've come to the conclusion a) the money the radiator shop charges is
well spent and b) just get a new core installed.

John