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.

Tank as removed from car
Tank as removed from car

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.

After cleaning with Marine Clean
After cleaning with Marine Clean

Then I removed the fuel gauge sender unit and the bung which has a mesh filter incorporated.

Sender unit
Fuel gauge sender unit removed from tank
Bung with mesh filter

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.

WiFi inspection camera
Tank interior (through sender gauge mounting)

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.

Some of the surface rust removed
Top of the tank

Now … ready for the next stage(s)!

*Marine Clean is now called Cleaner Degreaser