METAL BODY REPAIR - OD1653 - LESSON 2/TASK 2(a) Cracks in stamped brass radiator tanks must be patched. Spreading solder over the crack will not make a permanent watertight repair. (b) Wire brush or scrape the area around the crack one inch largerthan the patch to be installed. Dig down into the crack itself with apointed tool. Tin the cleaned areas and the underside of the patch, wipingthem clean while the solder is in a molten state. (c) Fit the patch in place as perfectly as possible, following thecontours of the tank. All patches should have rounded corners. (d) Hold the patch in place with a screwdriver and apply heat. Theproper amount of heat will be indicated when a stick of solder will meltwhen touched to the patch. (e) If proper care has been taken during the tinning operation, thepatch will be strong and watertight. Hold the patch in place until thesolder has set. (3) Blocking of Tubes Cellular (honeycomb) Radiators. A damaged tubemay not need to be repaired; it can be blocked off. Fifteen percent of thetubes in a radiator may be blocked off without adverse effects. (a) Heat face of tube near header plate and spread open with animprovised tool made from an old hacksaw blade sharpened on one end to theshape of a chisel. (b) Thoroughly tin the inside of the tube with tinning compound,using an acid brush to apply the tinning compound. (c) Apply flux and fill tube with solder. (4) Tubular Core.(a) Heat fins at the header plate and raise fins onehalf of an inchon each side of the tube to be blocked. (b) Apply heat to the tube and blow out the solder with an airgun.