My petrol tank seemed to be in reasonable condition apart from a healthy coating of surface rust on the top surface. The underside of the tank was less rusty, probably due to a combination of underseal and the usual grease that seems to accumulate under old Jags. I asked around, and the prevailing wisdom is that media blasting an old tank is likely to cause problems with old, and possibly thin, metal. A safer approach is to treat the rust chemically and then apply paint. I decided to take this approach, using POR-15 products.
First up I gave the tank a good clean with POR-15 Marine Clean*, I wanted to take a good look at the overall condition of the tank before going further.
Then I removed the fuel gauge sender unit and the bung which has a mesh filter incorporated.
But how much rust and accumulated gunk was on the inner surfaces of the tank? I used a WiFi inspection camera to take a video of the interior. This camera connects to a smartphone via WiFi and sends images and video directly to the device. The camera comes with the following accessories; a 45-degree mirror, a magnetic pickup and a pickup hook, which can be attached to the tip.
Video taken with inspection camera
Overall I was pretty comfortable with the tank condition and couldn’t see any reason not to proceed. I went ahead and ordered the POR-15 Fuel Tank Repair Kit.
There was still the issue of lots of surface rust and stubborn underbody sealer on the tank exterior. Probably illogically, given the warnings about the delicate nature of old tanks, I decided to wire brush at least the worst of this rust off. I hoped the same technique would deal with the stuck-on underbody sealer, which seemed to have glued itself to the surface.
Apart from covering everything in fine rust particles, this successfully cleaned the worst of the loose rust and underseal off the tank. The trick was knowing when to stop. Hopefully, I got this right.
Now … ready for the next stage(s)!
*Marine Clean is now called Cleaner Degreaser
Hi Phil . I use the following procedure with fuel tank, both bike and car.
The tank goes of to my friendly plating company after removing all coatings, dirt and grease. They put it in their derusting solution for the minimum amount of time to remove surface rust from the exterior of the tank. Make sure you rinse thoroughly to remove any remaining solution. Any heavy rust left can be removed by bead blasting. This method is problematic in that any thin spots in the tank will often become holes. This cleaning method does leave the tank in a safe state to repair any holes by welding. Immediately after repairs slosh the inside of the tank with tank sealer (POR make a good one). Carry out your leak checks and if OK finish the outside as desired. The tank should then reliably hold fuel for another 50 years.
Hi Kim, Thanks!, great description.
Hi Phil, I used a product similar to the POR15 Fuel Tank kit for my VW Bug. Very good result I thought. I understand the process will seal off any pin-hole spots. Outside was done in standard POR.
Hi Peter, this is the first time I have used any form of tank sealer. Good to hear that you have had success with similar products.
Before last stage it needs to be completely dry inside. Having a warm air gun comes very handy at that point. Using wifes hairdryer is not nearly as effective 🙂
I’d be too scared to try the hairdryer!