Cutting a access hole in a 1970T fuel tank

[ARCSinAK]

Im going to try and get the barn find running, sometime before storage it received a new fuel tank but it has sat for 18 years, There is a amazing amount of varnish and gunk inside the tank. I do not have access to a radiator shop on Kauai that has a submersion tank for cleaning. I'm wondering what other people have done to clean fuel tanks. A friend of mine tried solvents and abrasive stones, on a SC that sat for 10 years he finally gave up and bought a new tank. Has anyone removed the old fuel then filled a tank up with water and cut a large access hole for cleaning and then re-welded the tank back together.

Thanks for your time and knowledge.
JS

[euro911sc]

I just saw a thread where a guy did this, but it totally escapes me where I saw it! Basically, he cut a hole in the tank, cleaned out, then had a bolt on plate made that covered the hole. Once it is clean, though, you should be able to weld it up.

-Michael

[mcaterino]

This is the one - a very nice job, indeed!

Cleaning a Fuel Tank without damaging Plastic Swirl Pot

Mike

[Targalid]

Nice looking "barn find" there ArcsinAK. You guys must have some extra fine barns is all I can say.

[Grady Clay]

ARCsinAK,

You don’t need to cut anything.
Simply remove the tank from the chassis and pressure-wash it out.

The procedure linked above is for the ’73.5 and later CIS fuel tanks with a “Swirl Pot’ inside.
The swirl pot is a complicated plastic assembly and needs great care when cleaning the tank.

Good soap and hot water works wonders.
If you don’t think you got everything, you can use solvents – then wash more.
Set it in the sun to dry.

Procedure:
Siphon all the fuel out via the fuel level sender opening.
The necessary ‘disconnects’ are:
The filler hose.
The breather hose.
Remove the fuel level sender. You may need to clean inside the sender.
There should be one 7 mm (9 mm?) hose to the screen filter fitting.
Remove the drain plug.
Remove the screen filter from the tank and clean separately. Use a box wrench to loosen the fitting while the tank is still firmly anchored in the chassis.
Remove the three hold-downs to the chassis.
The tank will probably be stuck to the gasket, don’t damage the tank.

Inspect the chassis for rust under the tank.

You will need a new gasket for the level sender, new alu sealing rings for the drain plug and screen filter fitting and new 7 - 9 mm fuel hose.
(I suspect you will want to replace all the fuel hoses at the front electric pump. Be careful, the “Tee” is plastic.)
Use the N-S type hose clamps. Do not use worm-screw hose clamps as they will damage the hose.
I don’t think there were originally hose clamps on the supply hose to the pump. You should add these N-S clamps.
Carefully inspect the fuel filler rubber hose for deterioration. Any doubt, replace it.
If damaged, you will want to replace the gasket between the tank and the chassis.

Be VERY careful while there are gasoline fumes

Best,
Grady

[piggdekk]

Hello,
I'm having my carbs rebuilt and I wonder if I shouldn't fix the tank as well so that rust will not end up in the newly rebuilt carbs. Today I took some other parts to a local media blaster (who mostly works with bike and cars restoration) and he showed me how he fixes tanks. He basically has different types of tools to reach the inside of the fuel tank with his blasting media (not sure what he uses in this case, could be vegetal). By doing this he gets the internal of the tank very well cleaned without boiling it. Then he applies an epoxy product to seal the tank. The whole tank is kept rotating for 7-8 hours while the epoxy cures, and the final result is pretty amazing. I guess some of the media may get stuck in the tank, but it'll be bonded in the epoxy, so this is not a big deal. He quoted me about 200 euros for the whole process, including finishing the outside of the tank with an epoxy primer, and I think it is a fair price.

So now some questions: do You see any drawback in diong this on my 71T tank? There should be no swirl pot, as it is not a CIS car, and I'm not sure there is any screen in it that I need to remove upfront. Grady mentiones a screen in this thread for a 70T tank, but I couldn't find it in the part digrams.

Another question I have is about the internals of the tank. I've seen the picture of this guy who cutted his 73.5T tank, and there was some metal in the middle of the tank to prevent fuel sloshing. I guess that sheet metal could prevent the sand blaster to reach everywhere inside the tank without opening an extra hole. Could this be a problem?
many thanks
luca

[piggdekk]

got this picture where it looks like there is nothing in the tank that prevents to sand blast it from the sender unit hole.

luca