Gas Tank Leak Detection

[ferricsteed]

I have a TB with a slightly leaky 3 year old TC gas tank. The TC sending unit leaked though the usual spots but also the crimped right side panel half way up developed a slight seep which ruined the paint. I removed the sending unit and welded up the hole and the threaded holes. I brazed the seeping area. Before I repaint the tank, how do I check for leaks? Fill with alcohol? Fill withgasoline and go through the degassing process? Hopefully there are better ideas out there..
Tim Bloomfield
TB0613
Louisiana

[Steve Simmons]

Just a thought, but you could have the tank pressure tested at a radiator shop. If it's airtight then it's certainly liquid tight. I just had an antique tractor tank tested in this manner. Test and repair was a whole $20.

[ferricsteed]

I used my air compressor and pumped tank up to 10 psig. With a little soapy liquid, the bubbling showed the leaks quite well. So much for my welding prowess. How best to seal the pin holes in the welds? I plan to re-weld each pin hole and keep checking. Would just smearing Seals All or if soldering will wick into the pores may be a better solution?

[stephen stierman]

I welded a patch on a damaged tank on my Morgan, very tough to seal the pin holes. Ended up taking it to a radiator shop and they soldered it properly, that is the best way. I have used JB Weld on small leaks in seams as it does not appear to be affected by fuel.

[frenchblatter]

You've just reminded me. 10 years ago I had a slight drip of petrol from my Caterham ali tank. It had been rubbing on the chassis. As it was the depth of winter and below zero (the drips of fuel had frozen, which is why I noticed it), I slapped a bit of epoxy resin in the pin hole. Although the tank has been out several times since and I have a TIG welder I've just forgotten about it. It ain't broke, don't fix it.

[ferricsteed]

Update: Thanks for the suggestions. Steve, I pressured it up at home with an air compressor ~15 psig (with one suction line open). The soap bubbles clearly showed me how bad a welder I am. I took my time and through multiple iterations, I MiG'd the holes closed. Lots of welding and grinding. I am a much more proficient welder than when I started.
Now to tackle the rusty quarters............

Tim Bloomfield
TB0613
70F Louisiana

[Rocketsled]

Wicking type thread locker is used to seal porous welds. The Loctite product is 290, A.K.A. "Afterlock'
since it is also used to thread lock fasteners which have been tightened already.
Rocketsled