Standard tank drain tube

[dbeardslee]

I got another tank to add to my collection from ebay last week, and it looks pretty good with the exception of a totally plugged drain tube. I could just plug it in the rear, but if any gas sloshes through the vent it winds boogering up the paint and blowing right into your crotch. Not to mention water will lay in there when it's washed or you get caught in the rain. I'm thinking of having it replaced with a piece of steel brake line flared on the top and brazed in top and rear.

So anybody done a successful drain tube transplant on a standard tank? If so, how did you do it? I did one once with a piece of copper tubing and JB Weld, but I had to keep redoing the JB Weld every few months as the gas would eventually eat it. I'm looking for a permanent solution on this one.

[MaximPhil]

Hi dbeardslee,
IF the tube is corroded i leaks the contents of the tank. So if it is plugged at the top can you just clean it ( with soft tools so as not to break the tube) ?
Phil

[dbeardslee]

Hi dbeardslee,
IF the tube is corroded i leaks the contents of the tank. So if it is plugged at the top can you just clean it ( with soft tools so as not to break the tube) ?
Phil

It's plugged up with rust at both ends. Last time I tried to clean one I only succeeded in poking a hole in it. Still usable if you plug both ends, but you lose the drain capability, and sooner or later that tends to lead to a gas soaked crotch. And if you fill the tank and get a little gas coming out through the vent on the gas cap it's hard on the paint. I intend to fix this one properly 'cause other than that drain tube it's a decent looking tank. I plan on painting it and using it on Betsy and I want the paint job to last as long as possible.

[natemoen]

If I were to "fix it right" I would drill the tube out at both ends and remove the old one. I would then run a new tube through that was way too long. I would flare the top end big enough to fill the old hole and then braze it in. I would then bend the bottom end and braze that in down on the bottom.

I would probably use copper cause then it won't rust and seal up like steel will.

[dbeardslee]

If I were to "fix it right" I would drill the tube out at both ends and remove the old one. I would then run a new tube through that was way too long. I would flare the top end big enough to fill the old hole and then braze it in. I would then bend the bottom end and braze that in down on the bottom.

I would probably use copper cause then it won't rust and seal up like steel will.

I used copper the last time, and that's pretty much the way I did it. Except on the rear I cut the tube out, but that resulted in a bigger hole than I really wanted. That and I used JB Weld, which wasn't up to the task. I'll cut it off and drill it out in the rear this time which should result in a much smaller hole. That's a good idea, Nate.

The only problem I ran into putting it in from the top was getting the bend in the rear close to the tank. It worked but it was a little too close to the seat for my liking. I'm thinkin' I might have better luck feeding it in from the rear pre-bent and doing the flair last.

I'm going to have to go over and talk to them at the welding shop before I do anything and have a word with them about materials and options. I agree with you about copper not rusting like the originals like to do, but I've got other tanks that are just as old with open drain tubes. This bike lives in a garage, so it doesn't get much water down the tube, which I think may be the cause of a lot of the rusted tubes we see. I'll have to cogitate on that a bit, and get some input from the welders.

But I love the drilling out the rear idea - wish I'd done that the first time.

[CaptonZap]

So anybody done a successful drain tube transplant on a standard tank? If so, how did you do it? I did one once with a piece of copper tubing and JB Weld, but I had to keep redoing the JB Weld every few months as the gas would eventually eat it. I'm looking for a permanent solution on this one.

Yep, a piece of quarter inch copper tube soldered at each end, and I even saved the paint that shows. (The seat covers the exit wound) Careful tinning of the associated metals did the trick. That and a big soldering iron with a clean tip.

CZ

[dbeardslee]

Yep, a piece of quarter inch copper tube soldered at each end, and I even saved the paint that shows. (The seat covers the exit wound) Careful tinning of the associated metals did the trick. That and a big soldering iron with a clean tip.

CZ

So solder will stick to steel? IIRC when I took the tube out before it had what looked like brass around the tube in the rear, but the top was steel on steel that looked to be welded. Solder would certainly simplify things if I can keep the openings small enough. What kind of solder did you use?

[CaptonZap]

If you aren't concerned about saving the paint, then it is easier to do. I didn't want to re paint, so I did it this way.
Drill out the tube at the back with a biot slightly smaller than 1/4 inch. then drill it out with a 1/4 inch drill. That should leave the brass around the hole, with the fillet left intact. Wire brush the brass, and using a suitable flux to tin the brass, inside and out. Cut acid will work on brass, or get a paste flux used on electronics. Use a BIG iron, with a clean and tinned face. You need a LOT of heat in a hurry to get the job done without screwing up the paint. A clean surface is a must for successful soldering.
Go up to the top of the tank, and do the same thing.
Form the copper tube to fit, and tin the surface of the tube where it meets the tank holes. You must clean the copper surface to get the solder to flow. I use red Scotch Bright pads. Wipe excess solder off of the tube while it is still molten. This will allow it to be inserted intio the pre tinned holes.
Insert the copper tube, apply a bit of flux, and use the soldering iron to sweat the joints together, adding a little solder.
Now days, about all you will find is lead free solder, and it takes a little more heat to melt, being mostly tin, but if you have some old lead solder, it will work. The trick is to have a pre tinned surface area for the solder to stick to, which is why we left the fillet brass around the hole. The surface inside the hole helps the strength of the joint.
Clean the flux, test for leaks, re solder if you messed up. The importance of a good cleaning and tinning on both surfaces becomes apparent at this stage.
The original drain tube had a brace at the center of the run, but I don't know of an easy way to incorporate that into the replacement.

CZ

[DiverRay]

Solder sticks very well to steel! Do you remember the old "led sleds"? They were called that because of the lead solder used to shape the steel body.
Check my thread on the '79 re-do, and you will see I used solder to fill a few dimples in the tank. I used a torch and solder for plumbing, as I had it around.
The secret is to prep the steel BEFORE you put in the copper. Use acid flux to tin the tank, and then CLEAN everything before you try to paint.

[CaptonZap]

Addendum;

Yes, solder will stick to steel, as a lot of old cars with leaded repairs will attest to. A clean surface, the proper flux, and enough heat to get the metal hot will do it.
LaCo Regular Paste Flux is labled as being suitable for mild steel.
But the steel MUST BE CLEAN. Bright sanded steel clean. Apply flux and heat till solder flows. Paste fluxes can be degraded by flames, which is why I prefer a soldering iron with a clean. tinned surface.

CZ

[dbeardslee]

You guys are certainly giving me some good info. As far as paint - this tank has a few small dents I need to pull, and even if it didn't I still need to repaint it, so preserving the paint is not an issue. I don't have a big soldering iron - just a small adjustable iron for electronics. But I do have a propane torch - a couple of them actually. I've got the kind that go on a propane bottle and a small Bernzomatic pencil torch.

So, what are your thoughts on using fire to do the deed?

[DiverRay]

As CZ stated, the flux could have a problem with it, but that is one reason I used the pipe soldering stuff. Just heat the tank, and flow the solder into the copper from it. BE VERY CAREFUL with the flame, as it will heat the copper up in a HURRY. The other thing I would do is fill the tank with hot water, drain, and put the torch to the open cap to burn off any fumes BEFORE you start.

[dbeardslee]

As CZ stated, the flux could have a problem with it, but that is one reason I used the pipe soldering stuff. Just heat the tank, and flow the solder into the copper from it. BE VERY CAREFUL with the flame, as it will heat the copper up in a HURRY. The other thing I would do is fill the tank with hot water, drain, and put the torch to the open cap to burn off any fumes BEFORE you start.

I've got 5 gallons of Evapo Rust out in the mancave that's going to do its duty in the tank before I get to the soldering, so that should get rid of any residual gas. But it looks pretty doggone dry.

I had the same thought regarding flux since it tends to burns off quickly around 550 degrees and the metal reoxidizes pretty quick after that. I wonder if flux core solder would help solve that problem?

[DiverRay]

Not really, as it's made to be used with an iron. That is why I say use the plumbing supply stuff, as it's designed to be used with a torch.

[dbeardslee]

Not really, as it's made to be used with an iron. That is why I say use the plumbing supply stuff, as it's designed to be used with a torch.

Now I got it - high temperature flux. Devilish clever, those plumbers.