Fuel tank leakage

The (steel) tank of my Interstate has a small leakage near one of the front mounting studs, the fuel does not leak from the stud itself, it looks like a semi-circular crack around the mounting stud. This causes the isolation rubber to perish over time. can this be cured with a tank sealer? or is more drastic action required to cure this leakage.
Any advice is appreciated.

Peter.

It's a flex point, so if you just try and seal it it will crack the sealer as well and leak again. Only one RIGHT way to do it, and that involves welding. Now if your welder is real good, he can keep the 'showing' side of the tank cool with damp rags and welld the bottom. This should hopefully save your paint. All you'd have is an area around the crack that would need touching up and that would be hard to see anyhow. So might not be all bad, if you had a good welder.

Peter, It depends how bad the crack is and but ideally it should be repaired by brazing or welding a steel plate (larger than the crack diameter) with a hole (over the stud). Be sure the tank is empty and flushed out with hot soapy water to remove all vapour. If you are not happy with that you can remove all paint from the area, make a plate as for brazing and bond to the tank with a metal based epoxy adhesive. That worked for me on my 11.5 litre Roadster tank but since a full Interstate tank (23 litres?) weighs more than twice as much with full load it may not be adequate. I used 2mm steel and covered as large an area as possible to spread the load.

It can be hard to find a welder who will touch a fuel tank. The tank should be filled with something like argon to prevent exposive environments.

With that said, the last time I tried to get a welder to work on a Norton tank was around 1978 when I blew a seam out of my Interstate tank trying to remove a dent my knee had left in the side. I hooked it up to the compressor and pumped air into it and the dent started coming out...then of course so did the seam in the tank. I eventually put JB Weld on it and rode it for another two years that way. Amazingly without leaks. So while I don't want to put this out as advice, it is something to think about. You could use JB Weld or other appropriate epoxy and place a large washer over the stud to spread out the load area (assuming the washer would cover your crack). I have no idea how long you might get away with it. You would of course have to take the area down to bare metal and give it some texture.

Russ

If I was awake enough to think I probably would have noted Keith talking about the same kind of idea.

Peter R said:

The (steel) tank of my Interstate has a small leakage near one of the front mounting studs, the fuel does not leak from the stud itself, it looks like a semi-circular crack around the mounting stud. This causes the isolation rubber to perish over time. can this be cured with a tank sealer? or is more drastic action required to cure this leakage.
Any advice is appreciated.

Peter.

Click to expand...

Been there, done that.

I will almost guaranty the problem started with the rear mount near the seat. If this isn't held tight to the frame tube the front studs will flex the mounting bosses until a point that the metal will fatigue and crack.

The best way to fix this is to have a set of new bosses machined up, the originals are very small, make the new ones much more robust. Take a circular hole saw and cut/drill out the old ones...insert the new bosses and weld into place.

Think the last time I had this done, my machinist/welder did the whole deal for $50. Made the new bosses, cut the old ones out, welded the new ones in. All on a painted tank. The repair looks perfect, and is much better than stock.

This is not an uncommon problem, and is a very minor undertaking to repair...finding a welder to do this should be very easy.

Boy, I don't know where you are finding your welders. Every time I take something out for welding, it involves all the gold teeth in my head, right arm, left nut and youngest daughter. Maybe it's just my area, but there are plenty of farmers around here, think they would have a source. I can do some gas welding myself, but anything exotic i have to farm out.

Dave
69S

DogT said:

Boy, I don't know where you are finding your welders. Every time I take something out for welding, it involves all the gold teeth in my head, right arm, left nut and youngest daughter. Maybe it's just my area, but there are plenty of farmers around here, think they would have a source. I can do some gas welding myself, but anything exotic i have to farm out.

Dave
69S

Click to expand...

Have to find the right guy that works on motorcycle stuff regularly, pay cash, and never call to see when your parts will be done. The right guys never advertise and don't have a listing in the phone book.

Repairs like this are easily carried out using the TIG brazing process.............only problem being that very few welders are familiar with this, although its pretty much ideal for all sorts of repair work, and can even be used to build frames.

Another option is to search around and see if you can find a school or community college that teaches welding. Sometimes they'll do it for free 8)

builder said:

DogT said:

Boy, I don't know where you are finding your welders. Every time I take something out for welding, it involves all the gold teeth in my head, right arm, left nut and youngest daughter. Maybe it's just my area, but there are plenty of farmers around here, think they would have a source. I can do some gas welding myself, but anything exotic i have to farm out.

Dave
69S

Click to expand...

Have to find the right guy that works on motorcycle stuff regularly, pay cash, and never call to see when your parts will be done. The right guys never advertise and don't have a listing in the phone book.

Click to expand...

This sounds like me, I don't advertise much (due to my limited time right now with the kids), use cash, and finish projects ahead of schedule and keep customer up to date on progress. I have the capabilites of brazing, Stick, MIG, TIG and a spool gun for aluminum. If it's metal I can stick it together somehow.

I investigated locally and most welders and welding shops will not touch a gas tank. The first question they will ask is "It's not a gas tank is it?" Rinsing with hot soapy water I don't think is sufficient.

You have to find the right guy who knows what he is doing as stated earlier. Builder has it right.

I nervously brazed a patch using Mapp gas torch on a '51 Matchless tank after letting it sit empty for 2 years but I could still smell the petrochemicals while I was doing it and quite a bit of smoke was coming out the filler neck. I then used JB Weld over the whole repair. This was not anything structural.. my own damn fault for having a too long seat bolt which rubbed on the tank's frame tunnel.

Maybe try a Harley custom paint/body shop. We have one here that does tank pressure testing and also cuts open tanks to repair so I'm sure they could handle it. They love seeing a Norton tank come into the shop.

Peter,
I am a Tig welder in San-Francisco too far from you, a competent Tig welder will have no problem repairing you tank ! of course the paint will suffer. I would charge $ 60, keep on looking for that Tig welder. Gabriel.

I've welded up gas tanks before, first wash out tank with good detergent then procede by plugging a flexy hose into the exhaust of vechile running and then plugg it into the fuel filler hole of the tank to be welded. Obviously the exhaust gases need to escape out the filler hole aswell so dont block it up! The lack of oxygen ratio to fuel vapour allows you weld away.
Foxy