Actually I really want to have the rusting fuel tank of my '83 RX-7 properly replaced with a new or better "reclaimed" one but they are no longer made and most of the auto relaimation centers (junkyards to you and I) cite the near impossibilities of shipping a used tank these days. The nearest one in "really good shape for its age" (and he won't send digital pix of it either) is nearly 1000 miles round trip. Yes I am on vacation this week but I want to be driving the RX not fetching parts all across the US.
Correctly done the rusted through spot should be cut out and a new piece of
18-20 ga steel welded or brazed in place. I am a simple stick welder and this is way beyond my current abilities. I have not searched out a local master fabricator as yet but I can if need be. Truly there is a "L" shaped section about 6" by 12" that is fairly rusty on the outer surface but the inside coating seems to be fine. That is except for the 4 quarter sized spots that have actually rotted through. This section is where the frame rail comes in contact with the tank. I even found a mouse nest in the frame rail so I am sure that the little bit of salt the car has seen was also augmented by rodent piss. Yes, I did evict them for now but expect them back next winter when I store the car.My mechanic has suggested a product called POR15. He claims you clean the area grom grease and grime and any loose rusted metal and simply paint it on. It is thick enough so that he would add some fine fiberglass cloth to fill the holes and apply another coat right over it. After it is all cured I could then go ahead with the recoating of the inside of the tank although now that it is off and I have peered in through the openings it really looks fine. The main reason for the recoating though is that the rust issue is near the openings I am looking into the tank through and can not really assess how bad that side of the tank is internally.
After the holes are repaired I plan on a good all over cleaning and priming with Rustoleum Rust Reformer before spraying a body undercoating over the whole of it. I have followed many threads here and respect the knowledge behind this forum. That is why I ask you, The Experts", will this work and allow me to drive my sports car another 5 years or so? By then I hope to retire and can learn a lot more about brazing or wire welding.