The fuel tank on any vintage car can be the source of much aggravation—and in many cases, it can be the cause of many a car's early demise. We theorized that a rusty tank was one of the original reasons our car was laid up in a Montana barn for over a decade.
Our car has a very unique fuel tank, as it's got provisions for the later CIS fuel injection system as well as the larger pocket for a full-size spare tire. There are no good replacement tanks available, so we decided to flush and clean out our original for now. There was a combination of rusty flakes and aged out gasoline that was closer to varnish than a fuel.
We first dumped a few gallons of Castrol's Purple Power cleaner into the tank and let it sit for several days. We sloshed that around periodically to get into every corner of the tank. This cleaning detergent took care of the aged gas residue and gave us a good start on the cleaning process.
We then used a rust-dissolving phosphoric acid for a short period of time to kill the rust that was in the bottom of the tank. We kept this in for just a few hours before draining and drying the tank. We, of course, properly disposed of these nasty chemicals and cleaning by-products.
After the interior of the tank was cleaned out, we scraped the outside and reappiled a Wurth Schutz to match the original texture. This was treated with a coat of our grey exhaust paint, as well as a clear coat to more closely match the original grey pebbled finish. Note: if the issues with corrosion were a little better, this process would have worked. Unfortunately, we wound up replacing the tank
We then installed a new foam gas tank seal and bolted the tank in our car. We're in the process of hooking it up now.
