Love can last forever, but a truck frame most definitely will not. Most times, the engine of a truck will outlast a frame, which gets overtaken by rust. All is not lost though, as there is most definitely an answer to the question of how to repair rusted truck frames. Like all maintenance projects, this one takes time and power tools.
Know your enemy. You have to find out exactly how much rust there is on the frame before you begin any remedial work. If there appears to a large amount of rust, the whole frame should be examined. Sometimes, the problem is so severe that you just need to cut your losses and consider the truck frame a write-off. To make it easier to carry out the sandblasting process, remove any welded pieces, where possible, with a cutting torch or grinder.
Part of how to repair rusted truck frames involves getting rid of as much old paint and rust as you can. This is what the sandblasting is for, and should be carried out to expose the metal. If sandblasting is not possible, the frame can be sanded down manually. This will take a much longer time, but that shows how much you love your truck. Keep an eye out for damage like blistering or cracking. Any rusty parts will have to be cut away with a grinder, hacksaw or a torch. You might even need to reassemble the frame if the rust damage is extremely extensive.
Use a cardboard template to trace out replacements on new metal in order to substitute the sections that were removed earlier. Your measurements here will have to precise to ensure a perfect fit. Trace the template pattern onto the new piece of metal and cut out the pieces with a jig saw or use a router or drill bit for holes where needed. Sand the edges down smooth.
Apply rust-proof products to prevent any further rust damage to the existing frame, as well as protect the new patches. Always follow manufacturer’s instructions to the letter. Once the protective layer is dry, you may then commence with welding on the metal patches. A strong weld inside the frame will ensure durability and weld marks that are less visible. Work on a flat surface to ensure the whole frame is perfectly aligned. Sand and grind the weld till its smooth before applying primer to the frame. Once that is dry, the frame can then be painted.