Bonneville America Forums Forums Technical Forums General Tech Best way to test a tank for leaks?

So I'm working on my new tank. No, I didn't use the Legend one, just the top of it now welded (TIG, SS) to the top of an America tank where I made a cut-out to fit the "new" inlay. The weld itself looks pretty good, and is now grinded down and smoothed out.

However, before finishing the whole shebang, I wonder if anyone knows the perfect way (pref. easy as well) to test the weld for pinhole leaks etc? Don't want to risk another bubbly paintwork like I had with the last rebuild.

Thanks in advance!

I used my local radiator repair shop. They are equipped to pressure test your tank and to braze any pinholes at a fair cost.

If'n it wa my tank, I don't care HOW good the weld looks, I'd seal it with a liquid tank sealer. I use Kreem, but there are others. Even if the weld is good now, it could bleed/rust through a pinhole at a later time. That's why so many tanks on NEW bikes are coated from the factory.

If you can find a way to pressure up the tank to 15 Lbs. you would be able to find any and all weld flaws with some home made leak snoopy. 50% dish soap 50% water. If you have any leak at all, you will get bubbles. If a Tig weld looks good though, it probably is fine. Question, how did you remove the inevitable scale from welding on the inside of the tank? I have always either
torch Brazed or 50/50 soldered fuel tanks, so as eliminate said scale. That crap just keeps on coming loose a little at a time if you cant get at it with an abrasive.

15 lbs of pressure seems like way too much.In my younger days I worked in a radiator shop.We would put about 30 lbs in a radiator but only five in a large auto gas tank.

I just had a thought; if you plan on going the route of pressurizing it ya might be able to get an old gas cap, drill a small hole in the top and pop a valve stem in it. That should make a good seal and be a good way to manage the amount of pressure. Just a thought.

Thanks for the suggestions guys!

UPDATE! Got a tip from a friend using chalk powder and water. Mixed them together and painted the weld seam thoroughly, then let it dry (used the mrs hair dryer, but don't tell her). Put the gas cap on and poured in half a bottle of kerosene. In a couple of minutes there were six wet spots in the dry chalk. Marked them and hopefully later this week I'll hav a new go with the TIG or maybe I'll try soldering the holes. Funny though, there was no chance to see the leaks with the bare eye.

To be continued...

It can be hard to get welds perfectly leak proof, that's for sure. Now that you've added kerosene is welding going to be a problem with combustion in the tank? And if you do decide to go with a liquid sealer is there a concern with adhesion because of kerosene residue?

Sorry, but I had the English names mixed up. White spirit, not kerosene. And of course I'll be sure to get it all cleaned out before welding again.

I also have ordered the three bottles of Kreem to seal everything perfectly and to cover all of the inside.

Ahhh, chalk and water, the "whiting method", I should have thought of that being that NDT is my profession. But my first initail thought was Floresent penetrant, which I've used many, many times for leak checks, I only assumed you didn't have it or a blacklight, not sure why this method escaped me.

On another note I'm feeling the same as Keith about the kerosene. However I hear you can pipe in exhaust gasses from you car, lawnmower, or whatever and the c02 emission will cause an inert enviroment so less chance of a BOOM! Or something like that.