METAL BODY REPAIR - OD1653 - LESSON 2/TASK 2
(9) Drain Cocks. Drain cocks are found at the bottom of radiators and
are attached to the lower tank in one of the two following places:
(a) If the drain cock is attached to the outlet pipe, it may be
removed by unscrewing it.
(b) If the drain cock is not attached to the outlet pipe, it (or a
tapped fitting) is sweated to the bottom tank and is removed upon the
application of heat.
e. Radiator Assembly. A good soldering job is dependent upon the complete
tinning of the metal prior to soldering.
The use of a proper flux, the
close union of the parts to be soldered, and the application of adequate
heat to make the solder flow freely are important.
Tinning compound is composed of powdered tin and other chemical ingredients
compounded together. When mixed with water, it makes an oily liquid. This
liquid, when applied to a metal surface and heated, will leave a deposit of
tin or tin coating. It is not intended for use with aluminum or magnesium.
The compound is mixed with a half can of water in its own container. The
flux aids the compound in cleaning the metal. It is a white powder and is
mixed on a ratio of 1 pound of flux to five pints of water. This flux is
ideal for use on radiator work after the proper tinning of the metal has
It will cause the molten solder to have an excellent
capillary action. When using flux, caution must be taken to keep it out of
any open scratches or cuts in the skin. Rubber gloves should be worn when
The most commonly used flux is hydrochloric (muriatic) acid which has been
cut (killed) by adding pure zinc. In preparing hydrochloric acid for use in
soldering, place the desired quantity in a crock or other earthen vessel and
add zinc until it is saturated. Uncut muriatic acid is a yellowish color.
It becomes clear after it has been cut with zinc.
Muriatic acid is
objectionable because of its effects on the workman, due to the gases given
off when heated. The reaction of hydrochloric (muriatic) acid when zinc is
added produces as explosive hydrogen gas; therefore, the solution should be