I learned to lead when I went to trade school to learn Auto Body. It is definitely an art that can’t be taught by watching videos but is more of an OJT skill. First, the area to be leaded must be spotlessly clean down to bare metal. The only way to accomplish this (this area on your truck) would be to sandblast the area. Next, you need a tinning compound and have the area tinned completely as lead won’t stick to bare metal. Horizontal areas are much easier than vertical areas. The lead will puddle on horizontal areas but will run on verticals. Run is an understatement as the heat is very critical on verticals. Not enough heat and the lead doesn’t bond. Too much heat and you’ll loose most of your whole leading job and I mean not just the area you were heating but most of the lead you applied will literally fall to the floor and you get to start all over. You’ll set your OA torch to a wide flame similar to brazing but wider, unlike the pin point flame for welding. The heat range is critical and small. Once you reach you ideal temperature, you fan the torch (apply heat to the area your working then take it off to keep it at that temperature). Once you start to apply lead, you’ll need a special lead paddle to move the lead around because it doesn’t flow. Heat the area, melt a bit of lead, remove the heat and paddle the lead around until it starts to solidify then heat again. Repeat as required. You also have to watch that your not heating the surrounding area too much that you warp the panel. The paddle working surface, is kept oiled by an oil soaked rag that you lay the paddle on, which helps to glide the paddle across the surface.
Now I know what you’re all thinking. How does an oil soaked paddle not contaminate the lead. Once the metal is tinned, the lead sticks and the oil is not an issue. Now mind you, I have not leaded in over 40 years, but this is one area in autobody that I don’t believe has changed much.
The point that I am trying to make is, if you have not done this type of repair, its best left to someone that has. It will be very frustrating trying to learn this skill on your first job and more that likely you will not be happy with the results.
If that was my truck, I would probe the area with a pick to see if it is sound, then make a determination from there. If it is sound, I would rough up the existing epoxy and do a bondo repair as Bartamos has suggested. Once the repaired area is primed and painted, there will be no issues with the porous bondo. If its not sound, then replacing the metal is your only choice.
Last edited by Phak1; 12/02/2020 2:19 PM.
