PV: Fuel tank rust cleaning

[adarvasi]

Hello everybody, hoping that you are all safe and healthy!

As some of you know, I am restoring my 1962 PV544 to almost brand new condition, if Lennart Johansson from PV Autoparts is nice enough, I deserve a few shares of the company!
Now it was the turn to check the fuel sender, and it was in a terrible state of corrosion, then I checked the tank, and obviously wasn't much better; so I put a gallon of Evaporust and left it for a couple of days and washed the tank with high pressure water, the four walls and the bottom were pretty clean, not perfect, but the top was still rusted.
I checked some more how to do it and I found the electrolysis process to eliminate rust. I bough washing soda (calcium carbonate) mixed 1 table spoon of it with water, filled the tank to the brim, connected the wires and left it until it stopped bubbling (around 36 hours). The results were great, again on the 4 walls a and the bottom, you can see in the picture the black patina left by the electrolysis process, which is supposed to limit and/or eliminate future rusting. The top, however, was still rusted as you can appreciate with the boroscope pictures.
I am at a loss on what else to do, and seriously considering buying a new tank.
Before doing that, I will much appreciate your advice

[arcturus]

So, The sender is not expensive. Screw it back on tight. Turn the tank over,cut a hole just big enough for your pressure gun.repeat the de rust process, clean and dry and then weld on patch and fit new sender.Well,that's one way

[adarvasi]

Originally Posted by arcturus

So, The sender is not expensive. Screw it back on tight. Turn the tank over,cut a hole just big enough for your pressure gun.repeat the de rust process, clean and dry and then weld on patch and fit new sender.Well,that's one way

Hello Arcturus, that really seems a bit drastic! If it gets to that I will definitely go for a new tank

[c1800]

It appears that the solution was not in contact with the inside top of the tank. You could fashion some kind of seal/cover for the sender hole and repeat the process with the tank upside down. If that’s not possible then possibly a radiator shop or similar place that can dip the tank in a caustic solution would work. More expense , but probably cheaper than a new tank.

Edit. Upside down with the sender in the hole.

[arcturus]

Originally Posted by adarvasi

Hello Arcturus, that really seems a bit drastic! If it gets to that I will definitely go for a new tank

OK,then fit sender back on tight and turn tank over and de rust solution through fuel filler?

[arcturus]

Originally Posted by adarvasi

Hello Arcturus, that really seems a bit drastic! If it gets to that I will definitely go for a new tank

OK,then fit sender back on tight and turn tank over and de rust solution through fuel filler? Where there's a will there's a way ( and where there's a way there's a willy) Unless the rust is absolutely falling off into the tank the top is not so important as the rest as fuel doesn't get that high.An extra filter just before pump will take care of any particles

[amazon69]

I have just done this with my massive Bristol tank. I used Bilt Hamber Surfex HD and then DEOX C, which is great. BUT..to get things really clean I put in to the empty tank a lot of old coins and stones. (I had washed them all beforehand) I then wrestled with the tank in all directions. The coins scraped the flat surfaces, and the stones knocked off everything else. I then hosed out the tank and it is super clean..and it was really awful beforehand. A few coins didnt want to come out but they did in the end.

[arcturus]

Only problem what with rust eating away at the metal, once rust removed the tank can be pretty thin and develop pin holes.

[adarvasi]

Thank you Arcturus for your suggestions, the thinness of the metal is a very valid concern.
In another forum in the US, Baltasar Fernandez from Barcelona suggested to cut the tank open (see video) and re welded after thoroughly cleaning and applying a coat of resin inside.
I will try that, and if it fails I will buy a new one, but it's a good learning experience that may work, I have to find an excellent welder, though.
I attached a picture of the tank opened and sand blasted. Have videos of the process but could not upload them

[mocambique-amazone]

Nono, don't cut the tank. Put in the sender, place the tank at the side and try the calvanic process again. Don't forget to protect the tank later. Good luck, Kay